EEG and behavioural correlates of mild sleep deprivation and vigilance.

OBJECTIVE: The current study investigated the behavioral, cognitive, and electrophysiological impact of mild (only a few hours) and acute (one night) sleep loss via simultaneously recorded behavioural and physiological measures of vigilance. METHODS: Participants (N = 23) came into the lab for two testing days where their brain activity and vigilance were recorded and assessed. The night before the testing session, participants either slept from 12am to 9am (Normally Rested), or from 1am to 6am (Sleep Restriction). RESULTS: Vigilance was reduced and sleepiness was increased in the Sleep Restricted vs. Normally Rested condition, and this was exacerbated over the course of performing the vigilance task. As well, sleep restriction resulted in more intense alpha bursts. Lastly, EEG spectral power differed in Sleep Restricted vs. Normally Rested conditions as sleep onset progressed, particularly for frequencies reflecting arousal (e.g., delta, alpha, beta). CONCLUSIONS: The findings of this study suggest that only one night of mild sleep loss significantly increases sleepiness and, importantly, reduces vigilance. In addition, this sleep loss has a clear impact on the physiology of the brain in ways that reflect reduced arousal. SIGNIFICANCE: Understanding the neural correlates and cognitive processes associated with loss of sleep may lead to important advancements in identifying and preventing deleterious or potentially dangerous, sleep-related lapses in vigilance.

The occurrence of acidic drugs and caffeine in sewage effluents and receiving waters from three coastal watersheds in Atlantic Canada.

Pharmaceuticals, by design, induce biological responses in animals and humans at very low doses, making their presence in the aquatic environment an issue of concern. Prescription and over-the-counter drugs commonly found in wastewater are discharged on a continuous basis into the waters of two coastal watersheds in Atlantic Canada. Ten acidic drugs and caffeine were observed in the final effluents of sewage treatment facilities in Millcove (Halifax watershed), and Trenton (Pictou watershed), Nova Scotia. Naproxen and ibuprofen, two highly used non-steroidal anti-inflammatory drugs (NSAIDs), and caffeine, were the predominant compounds. Naproxen, ibuprofen, salicylic acid (metabolite of acetylsalicylic acid), diclofenac (NSAID) and gemfibrozil (lipid regulator) were also detected in the low ng/L range in the receiving waters of treated and untreated sewage outflows. Acidic drugs were not detected in the marine waters of the Cocagne watershed located in southeast New Brunswick. This watershed was evaluated for the possibility of contamination of near-shore coastal waters from domestic septic systems in the vicinity of a densely populated cottage area. The observation of traces of caffeine suggests some organic pollution in the area.

Cystic smooth-muscle tumor of the liver and spleen associated with Epstein-Barr virus after renal transplantation.

Immunosuppression is known to favor the development of various types of tumors. After organ transplantation, the risk of lymphoproliferative disease, whether clonal or not, is particularly increased and clearly associated with Epstein-Barr virus infection. We report a case of an unusual large cystic tumor of the liver with satellite hepatic and splenic nodules occurring 4 years after renal transplantation. Radiologic examination showed a rich vascularization of the tumor. Light and electron microscopy of a surgical liver biopsy, completed by an immunohistochemical study, demonstrated a well-differentiated tumor of smooth-muscle origin. Using in situ hybridization, we showed large amounts of Epstein-Barr virus messenger RNAs within the tumor cells. In addition, Southern blot analysis revealed that viral DNA was present in the form of a single monoclonal episome within the tumor. The polymerase chain reaction analysis of the genomic DNA of tumoral cells also indicated a monoclonal pattern. At last, the tumor was shown to be of host origin. Six months later, and despite three courses of chemotherapy, the tumoral lesions were unchanged. This case underlines the role of Epstein-Barr virus infection in the development of unusual and clonal smooth-muscle tumors after organ transplantation. The evolution of these rare tumors is uncertain.

A Macintosh program for result analysis in HLA genotyping by the modified PCR-RFLP method.

We describe in this report a computer program for easy interpretation of polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) patterns generated during HLA Class II typing by the modified PCR-RFLP method. HLA-DQA1, HLA-DQB1, HLA-DRB1 and HLA-DPB1 typing result analysis are thus greatly simplified. The program also allows video capture and image storage, which are becoming a new standard in molecular biology laboratories.

Mixed chimerism after sex-mismatched allogeneic BMT: evaluation of two molecular techniques.

Two different molecular techniques were used to monitor chimerism following 17 non-T cell-depleted BMTs from female donors to male recipients: pHY10, a Y chromosome-specific probe (Southern or slot blots), and a set of primers for Y chromosome sequence-specific amplification by the polymerase chain reaction (PCR). On Southern blots, male DNA was detectable at a level less than 1% of 10 micrograms DNA while cross-reactivity with autosomal sequences was avoided. On slot blots, male DNA was reliably detectable at levels less than 0.5%, even in small sample (0.5 microgram DNA). With the PCR technique, male DNA was detectable at levels of 1:10(6) to 1:10(7) of 0.5 microgram DNA. Slot blot and PCR results were concordant in 19 of 23 samples. Both techniques demonstrated a constant small mixed chimerism during the first year after BMT and in four of nine patients, this chimerism persisted even longer (up to 29 months after BMT).

Biomechanical analysis of swing-through gait in paraplegic and non-disabled individuals.

The purpose of this study was to determine if the deficit of motor function affects the displacement of the lower limbs and increases the physical strain of upper-body musculature in paraplegic individuals performing swing-through gait. A biomechanical model consisting of four linked rigid bodies was developed to analyze this type of gait. Data were obtained on the spatio-temporal characteristics, kinematics and kinetics from a sample of eight non-disabled and nine paraplegic individuals performing swing-through gait. Net muscle moments acting on the segments and mechanical powers at three joints (shoulder, elbow, hip) were estimated during a complete gait cycle from basic force equations and moments of force acting on a rigid body. Results show that the two groups selected a similar comfortable speed suggesting that the type of gait per se is an important factor in the selection of speed. Paraplegic individuals had a longer crutch stance phase duration than the non-disabled due to inadequate hip muscle activations as confirmed by the moment of force and power analyses. Moreover, a higher moment of force at the shoulder was observed in the paraplegics individuals, mostly during the crutch stance phase. Consequently, the loss of motor function of the lower limbs in paraplegic individuals modifies the biomechanical pattern of swing-through gait compared to non-disabled individuals, and seems to increase the physiological demand on the upper limbs during the stance and swing phases of the gait cycle.

Validity and reliability of a new electrogoniometer for the measurement of sagittal dorsolumbar movements.

This study was designed to determine the validity and reliability of a new electrogoniometer devised and developed for the measurement of sagittal dorsolumbar movements (T8-S1). The validity was measured in 10 normal subjects by comparison of the angle values obtained with the electrogoniometer with those obtained with the two-inclinometer method previously validated with x-ray measurements. The total range of movement was divided into 5 degree steps, and the angle value obtained with both methods was recorded at each of these steps. The testing procedure was repeated (retest) after removal and reattachment of the electrogoniometer. Because the potentiometer of the electrogoniometer measures angular changes indirectly from changes in the curvature of a flexible slat, a special individual calibration procedure was applied, and computation of the electrogoniometric angles (Ec) representing the dorsolumbar movement was made by software. Regression analysis of Ec in relation to corresponding inclinometric angles gave a slope of 1.03 and a Pearson's correlation coefficient of 0.97, indicating a high concurrent validity between the two methods. The intraclass correlation coefficient between test and retest (ICC = 0.982) confirmed the high reproducibility of the measurement procedures. The length of the slat can be changed to adapt the electrogoniometric system to different statures. Under standardized conditions, this new electrogoniometer can provide continuous measurements of sagittal dorsolumbar movements that are reproducible with an accuracy comparable to that obtained with the two-inclinometer method.

Differential effects of a flexor nerve input on the human soleus H-reflex during standing versus walking.

A conditioning (C) stimulus at group I strength was delivered during standing to the common peroneal (CP) nerve before a test (T) stimulus at several C-T intervals ranging from 0 to 150 ms. At sufficiently long C-T intervals (100-120 ms) the soleus H-reflex was strongly inhibited despite little, or no change, in the background level of EMG activity. This finding indicates that a significant portion of the inhibition occurs at a premotoneuronal level, likely via presynaptic inhibition of the Ia-afferent terminals. During standing, at C-T intervals of 100-120 ms (optimal C-T interval) a conditioning stimulus to the CP nerve of 1.5 times motor threshold (MT) intensity reduced the soleus H-reflex by an average of 45.8%(n = 14 subjects). The conditioning stimulus always produced a clear inhibition of the H-reflex during standing at these C-T intervals. The effects of this conditioning stimulus on the soleus H-reflex were then determined in the early part of the stance phase of walking. In contrast to standing, the conditioning stimulus produced little or no inhibition during the early part of the stance phase of walking (average inhibition 45.8 vs. 11.6%, n = 14 subjects). The soleus background EMG, and the soleus and tibialis anterior M-waves were essentially the same during standing and walking. Furthermore, there was no shift of the optimal C-T interval during walking. The difference in the effects of the conditioning stimulus was not due to differences in the size of the test H-reflex in each task. It appears to be due to a genuine task-dependent change in the input-output properties of the underlying spinal cord circuits. There are at least two, mutually compatible, explanations of these results. Firstly, during walking the intraspinal terminals of the afferent fibres (group Ia and Ib) conducting the conditioning volley may be presynaptically inhibited, or their input gated at the interneuronal level. Secondly, on the assumption that the conditioning stimulus is acting via the presynaptic inhibitory network in the spinal cord, it is possible that during walking this network is saturated as a result of increased central or peripheral synaptic inputs. Finally, it seems unlikely that differences in the refractoriness of the CP nerve between the tasks may be involved; the reasons for this are presented in the discussion.

Studies on the HLA Class-II Antigens of a Patient Presenting a Double Alloimmunization Following Posttransfusion Purpura.

In the Caucasian population, platelet incompatibility within the HPA-1 (Pl(A1/A2)) and HPA-5 (Br(a/b)) alloantigen systems are the two most likely causes of post-transfusion purpura (PTP) and neonatal alloimmune thrombocytopenia. However, the way in which HLA (class-II) antigens participate in alloantibody formation is unclear. The patient (M-J.G.) is a middle aged woman with two children who developed a severe PTP (< 2000 platelets/µ1) 8 days after receiving red cell concentrates during coronary bypass surgery. During treatment with intravenous gamma-globulin and corticosteroids, her platelet count peaked, fell again, and returned to normal over a period of several months. Western blotting and/or the monoclonal antibody specific-immobilization of platelet antigens (MAIPA) assay performed with serum prepared at the height of her initial thrombocytopenia revealed antibodies to both the Pl(A1) and the Br(a) alloantigens. This rare combination prompted us to study the expression of specific HLA class II antigens in the patient. HLA-DR and DQ typing was performed from genomic DNA by the recently developed polymerase chain reaction-restriction fragment length polymorphism procedure (PCR-RFLP). The patient was found to express the DRB1*1302/1303 and DRB3*0101/0301 alleles (serological specificities: HLA-DR6 and DR52a/c respectively). She also expressed the DQA1*0102/0501, DQB1*0601 and DQB1*0301 alleles. Thus, this case provides further evidence linking an immune response to Pl(A1) and Br(a) antigens with HLA-DR52a/c and DR6.

Locomotor rehabilitation in a complex virtual environment.

Virtual reality (VR) technology offers a new and safe way to increase practice time and provide the varied environments and constraints needed to optimize locomotor training. Our specific objectives are (1) to create a virtual environment (VE) coupled with a self-paced treadmill for locomotor training; (2) to compare temporal and distance measurements of gait during treadmill walking while looking at different scenarios of VE; and (3) to develop a protocol optimized for the training of locomotor disorders after stroke. A motorized treadmill was mounted on a six-degree-of-freedom motion platform. VEs were created using commercial software (SoftImage) and projected on a large screen, while system control was administered through the CAREN software (Motek BV). The instantaneous treadmill speed and scene progression were servo-controlled. Preliminary results show that healthy subjects are able to have full control of their own walking speed both on the treadmill and within the virtual scene, while experiencing a strong sense of presence. A street crossing training protocol has been developed for locomotor training. It is expected that locomotor training with increasingly complex VEs will allow persons with stroke to increase progressively their locomotor capacity, as required and entrained by the VE.