A dose–response study of total sleep time and the ability to maintain wakefulness

The apparent connection between sleep debt, performance decrements and workplace accidents has generated a need for feasible vigilance tests that focus on the quantification of daytime sleepiness in occupational settings. The objective of this study was to evaluate the sensitivity of the Maintenance of Wakefulness Test (MWT) to acute sleep deprivation of various doses. Eight healthy female volunteers, mean age 28.9 years (range 23–36), participated in this laboratory study. After an adaptation night, the subjects were assigned to four counterbalanced, randomly ordered night sleep conditions. These four conditions allowed for a time in bed (TIB) of 0, 2, 4 or 8 h, producing a total sleep time of 0, 113, 218 and 427 min, respectively. The ability to sustain wakefulness was measured after the TIB period at 11.00 and 17.00 hours by the MWT. Analysis of variance with repeated measures was used to study the dependence of MWT sleep latencies on the immediately prior TIB period. Both the latency of stage 1 sleep onset and the appearance of slow eye movements reduced significantly with increased sleep loss. The quantitative relationship between the previous total sleep time and the subsequent MWT sleep latencies followed an exponentially decaying function showing a high sensitivity to acute, severe night sleep loss but low sensitivity to less severe sleep restrictions. It is concluded that the MWT seems to be a sensitive method for the estimation of acute sleep deprivation. The test results appear, however, non-linearly related to the earlier sleep debt.     

Visual spatial attention to stimuli presented on the vertical and horizontal meridian: An ERP study

In the first experiment, 48 subjects carried out a visual spatial attention task. Stimuli were presented at the vertical meridian, either above or below a fixation dot, and the subjects were instructed to attend to one of these stimulus positions and ignore the other position. In three different conditions, the distances between stimulus positions and fixation were 0.5°, 0.9°, and 1.3°. Subjects searched for the presence of prememorized target letters at the attended location: memory load was one or four items in different conditions. The P1/N1 enhancement typically found on the horizontal dimension was not observed on the vertical dimension. Instead, a positive shift of the attended compared with the unattended stimuli was found, which was most prominent at anterior electrodes. This positivity showed effects of the distance manipulation. The N2b-P3a effect of attention and the effect of memory load (search negativity) normally present in this kind of selective search task were also found. Reaction times were faster when attention was directed above fixation than when it was directed below fixation. The event-related potential data suggested that this difference could be attributed to a more efficient neglecting of irrelevant stimuli presented below fixation. In Experiment 2, we examined whether the absence of the P1/N1 enhancement as the result of spatial attention in Experiment 1 could be attributed to (a) the presentation of stimuli along the vertical meridian instead of along the horizontal meridian, (b) the use of midline electrodes instead of lateralized electrodes, and (c) the relatively small spatial separation between the relevant and irrelevant stimuli. Twelve subjects searched for the presence of a single target letter at an attended position in three different conditions. In two of the conditions the letters were presented to the left or right of fixation. The distance between fixation and the stimulus positions was 1.3° in one of these conditions and 3° in the other condition. In the third condition, the stimuli were presented at 3° above or below fixation. In all three conditions effects similar to those in Experiment 1 were observed. In addition, in all three conditions an enhancement of the P1 and N1 components was found at two lateral occipitotemporal electrodes.     

Effect of intranasal fluticasone proprionate on the immediate and late allergic reaction and nasal hyperreactivity in patients with a house dust mite allergy

Background Patients with perennial allergic rhinitis develop nasal symptoms not only after allergen exposure, but generally also after non-specific stimuli. Objective To evaluate the effect of 2 week's treatment with fluticasone propionate aqueous nasal spray (FPANS) on the nasal clinical response, inflammatory mediators and nasal hyperreactivity. Methods Twenty-four rhinitis patients allergic to house dust mite (HDM). participated in a douhle-blind. placebo-controlled crossover study. After 2 week's treatment with placebo or 200 μg FPANS twice daily, patients were challenged with HDM extract. Symptoms were recorded and nasal lavages were collected for up to 9.5 h after challenge. Nasal hyperreaclivity was determined by histamine challenge 24 h later. Results Because of a carry-over effect for the immediate symptom score, for this variable only the data from the first treatment period were used. FPANS treatment resulted in a significant decrease of nasal symptoms with 70%. 69% and 63% after 100. 1000 and 10000 Biological Units (BU)/mL of HDM extract respectively. Active treatment resulted in a 76% decrease of the late-phase symptoms. FPANS treatment significantly reduced albumin influx after HDM 1000 BU/mL with 62% and tended to reduce tryptase release after HDM 1000 BU ml. (P 0.0629). During the late phase FPANS treatment reduced albumin influx with 67% and eosinophil cationic protein (ECP) release with 83%. No effect of FPANS was seen on histamine levels. FPANS significantly decreased histamine-induced symptom score with 34%, secretion with 32%, and sneezes with 41%. Conclusion FPANS significantly inhibits the immediate and late allergic response, and nasal hyperreactivity, probably by suppressing mast cells and eosinophils in the nasal mucosa.     

Deuterium Isotope Effect on the Metabolism of the Flame Retardant Tris(2,3-dibromopropyl) Phosphate in the Isolated Perfused Rat Liver

The metabolism of tris(2,3-dibromopropyl) phosphate (Tris-BP)was compared with that of completely deuterated Tris-BP (D15-Tris-BP)in an isolated, recirculating rat liver perfusion system inorder to determine the relative quantitative importance of twodifferent biotransformation pathways of Tris-BP: (i) cytochromeP450-mediated metabolism and (ii) GSH S-transferase-mediatedmetabolism. To accomplish this we quantitated the biliary excretionof S-(3-hydroxypropyl)glutathione (GSOH) as a marker metabolitefor cytochrome P450-mediated metabolism and that of S-(2,3-dihydroxypropyl)glutathione (GSOHOH) as a marker metabolite for GSH S-transferase-mediatedmetabolism. Completedeuterium substitution of Tris-BP significantlydecreased the formation of GSOH, whereas there was no effecton the formation of GSOHOH. Because our previous studies showeda large decrease in genotoxicity of D15-Tris-BP compared toTris-BP, the present results support our hypothesis that cytochromeP450-mediated metabolism is responsible for the genotoxic effectsof Tris BP in the rat liver.     

The Feasibility of Fully Automated Pacemaker Advise in Treating Atrial Tachyarrhythmias

Background: Modern pacemakers continuously store significant cardiac‐related events. Interpreting these data and reprogramming the pacemaker can be time‐consuming and demands expert knowledge. A software‐based expert system, the therapy advisor (TA), was developed, which analyzes stored data and provides reprogramming recommendations. This study addresses whether pacemaker experts consider the messages that are automatically generated appropriate in the management of atrial tachyarrhythmias/atrial fibrillation (AT/AF). Methods: This observational, international, multicenter study follows 150 patients with suspected or documented atrial arrhythmias who received a dual‐chamber pacemaker (model Vitatron T‐70, Medtronic Inc., Minneapolis, MN, USA) incorporating the TA. The TA summarizes technical and clinical data stored in the pacemaker into key messages and may suggest programming changes. Twenty‐five cardiologists examined their patients per normal practice during two follow‐up visits. They reported the therapy changes they deemed necessary without initially reviewing the TA messages. Next, they rated their satisfaction with and the clinical relevance of the TA messages and recorded the final therapy changes. Results: The TA generated (mostly AT/AF‐related) main observations in 49% and programming advice in 33% of the patients. The experts rated 95% of the TA messages as satisfactory and deemed therapy changes necessary in roughly half the patients. Pacemaker changes in AT/AF therapy or general settings were prompted primarily by the diagnostic information stored in the device. Medication changes were mostly led by the symptoms reported by the patient. Conclusion: This study demonstrates that experienced cardiologists agree with 95% of the observations and programming suggestions that the TA automatically generates. (PACE 2010; 605–614)     

Injuries in The Netherlands: A survey

As a repeat of a survey carried out in 1986–1987, a telephonesurvey was conducted. More than 25,000 households, comprisingover 67,000 persons, were questioned about any recent traffic,home and leisure, sports and occupational injuries. Expressedas a national number, a total of approximately three millionaccident victims required professional medical treatment ina 12 month period in 1992 and 1993. By far the largest categoriesof injuries were home and leisure injuries and sports injuries(1.6 million and 1.1 million respectively), followed by trafficinjuries (340,000) and occupational injuries (230,000). Approximately59, 000 victims were admitted to hospital, 830, 000 were treatedin an accident and emergency department/out-patient clinic and2 million visited a general practitioner. Based on the proportionof hospital admissions and fractures, traffic injuries are consideredthe most severe type of accident Compared with the results of1986–1987, the total number of accident victims (exceptoccupational injuries) increased by 11%. For traffic injuriesthis increase was 30% and for home and leisure injuries 16%.There was no significant change for sports injuries. In spiteof preventive measures, the accident problem In The Netherlandsis not decreasing. This means that preventive efforts shouldat least be maintained at the present level.