Changes in sleep architecture following chronic mild stress.

Chronic exposure to mild unpredictable stress causes subsensitivity to rewards (anhedonia). These effects are reversible by chronic treatment with antidepressant drugs, and have been proposed as an animal model of depression. In the present study, sleep architecture, particularly the rapid eye movement (REM) component, was mapped in rats following exposure to chronic mild stress. The study used a unique large scale automated sleep system to record and analyze the sleep signals from 32 rats simultaneously. The effects of stress on sleep were maximal following 21 days of stress, at which time the stressed animals demonstrated decreases in active waking and deep sleep, and disruptions of REM sleep. The changes in REM sleep included increases in the duration of and transitions into REM sleep over the sleep part of the sleep-wake cycle, and most importantly, a reduced latency to the onset of the first REM period. These sleep abnormalities, and in particular the decrease in REM latency, are consistent with those reported in endogenous depression. The results provide further support for the validity of the chronic mild stress paradigm as an animal model to study the mechanisms underlying endogenous depression.

[Sarcoidosis]. / Sarcoïdose.

Sarcoidosis seldom occurs in children. The illness has variable clinical manifestations. Diagnosis is often delayed because of the variable clinical manifestations and the sporadic occurrence. The case history of one patient is described. The presentation, diagnostical approach. therapy and course of sarcoidosis is discussed.

Effects of various drugs supposed to interact with serotonin on PGO frequency changes induced by reserpine and 5-hydroxytryptophan.

Reserpine induced ponto-geniculo-occipital (PGO) spikes in the lateral geniculate nucleus. This was used as a model to evaluate the possible anti-reserpine effects of Org GB 94-1,2,3,4,10,14b-hexahydro-2-methyldibenzo[c,f]pyrazino [1,2-alpha]azepine monohydrochloride-methiothepin, imipramine and atropine. In cats, under local anaesthesia, 3.2 mg/kg of methiothepin (a serotonin antagonist and neuroleptic) increased PGO density while 5-hydroxytryptophan (5-HTP) effects were blocked. A dose of 0.32 mg/kg of imipramine or atropine greatly reduced PGO density while potentiating 5-HTP effects. Org GB 94 had no effect in doses up to 10 mg/kg, where a slight decrease of PGO density was found, while 5-HTP effects were unchanged. At 32 mg/kg, EEG was pronouncedly changed by Org GB 94 but only a short-lasting decrease in PGO density was noted. On the basis of these results it seems improbable that the behavioural effects of Org GB 94 are to be explained by the same mechanism (i.e. serotonin uptake inhibition) as that of imipramine.

A large scale, high resolution, automated system for rat sleep staging. I. Methodology and technical aspects.

An automatic rat sleep classification system is described which records and analyses bioelectrical signals from 32 rats over extended periods of time. At present this system is used routinely for the screening of drug effects on sleep. The analysis is based on 3 signals, the parieto-occipital EEG, nuchal EMG and a movement indicator signal. The on-line analysis is done per epoch of 2 sec and involves power spectral analysis of the EEG and rectification and integration of the EMG and movement signals. The automatic sleep staging into 6 stages (active and quiet waking; quiet, deep, pre-REM and REM sleep) is performed off-line. Parameters derived from a discriminant analysis of visually scored tracings of individual rats constitute the basis for the automatic scoring procedure. The movement index is used to discriminate between active and quiet waking, while the use of the EMG level improves the separation of waking and REM sleep. After the construction of hypnograms from these computer scorings a set of parameters can be extracted which characterizes the sleep-waking behavior of each individual rat. These parameters are then used to compare statistically the 2-4 treatment groups which make up each experiment of 32 rats. Experimental validation of the system is reported in an accompanying paper.

A large scale, high resolution, automated system for rat sleep staging. II. Validation and application.

An automated rat sleep staging system was used to describe sleep-waking behaviour in a large number of rats. The computer scorings were validated by visual analysis of a limited set of data by two human raters and the agreement varied between 82 and 100% for homogeneous segments of the different sleep-waking stages. The automated system proved to be very consistent in view of the small variation in placebo values over 110 experiments. The data show that classification of rat sleep waking behaviour into 6 different stages is both advisable and feasible. The experiments further show that rat age (over a range from 0.5 to 2 years) does not greatly affect rat sleep-waking behaviour.

Venous hypertension of the hand caused by hemodialysis shunt: immunofluorescence studies of pericapillary cuffs.

BACKGROUND: Venous hypertension of the hand is an unusual complication of an arteriovenous shunt in patients receiving dialysis. OBJECTIVE: We investigated whether in venous hypertension of the hand pericapillary cuffs are present and whether they consist of fibrin and other components. METHODS: Biopsy specimens were taken from three patients with a side-to-side shunt and venous hypertension of the hand, from three patients with an end-to-side shunt without venous hypertension, and from three control subjects. The specimens were stained with antibodies against fibrinogen, fibrin, plasminogen activator inhibitor-I, factor VIII-related antigen, and collagen type IV. RESULTS: Pericapillary cuffs consisting of fibrin only were observed in patients with venous hypertension of the hand. In this fibrin network, factor VIII-related antigen and collagen type IV were also present. The finding of plasminogen activator inhibitor-I in the pericapillary cuff in the patient with the most severe signs of venous hypertension may indicate that breakdown of this fibrin cuff is impaired. CONCLUSION: Pericapillary cuffs may be of pathogenetic significance in venous hypertension of the hand.