HLA B27 and defects in the T-cell system in Whipple''s disease

The cellular immune system was tested in nine patients with Whipples' disease. Three patients had active disease, and six had been in remission for up to 10 years. Intradermal delayed hypersensitivity reactions to candidin, trichophytin, tuberculin and varidase, T-cell counts as determined by E-rosettes, allogeneic stimulation of lymphocytes in the mixed lymphocyte culture, and mitogenic activation of lymphocytes by concanavalin A, phytohaemagglutinin and by pokeweed mitogen, were tested in the patients and compared with control subjects. HLA typing was performed in all patients. The reaction to tuberculin and varidase, the T-cell counts and the activation of lymphocytes by concanavalin A were significantly reduced in patients with active disease and in patients during remission. The reaction to candidin and trichophytin was poor even in the controls. The mean results of the mixed lymphocyte culture, phytohaemagglutinin, and pokeweed mitogen activation tests were not significantly different from the controls. In patients with active disease the mixed lymphocyte culture reaction and the T-cell counts were less than in patients in remission. The results suggest a persistent defect of T-cells in patients with Whipple's disease, a defect that is more severe in patients with active disease. The finding of HLA B27 in four of thenine patients supports the hypothesis of primary rather than secondary impairment of the cellular immune system in Whipple's disease.     

Different cortical activation patterns in blind and sighted humans during encoding and transformation of haptic images

In this study, we investigated whether the occipital cortex of blind humans is activated during haptic perception and/or transformation of a haptic image. Slow event-related brain potentials were monitored from 18 electrodes in 12 sighted and 15 congenitally blind participants while they were engaged in a haptic mental rotation task. In both groups, slow negative shifts appeared over (a) the frontal cortex at the beginning of each processing episode, (b) the left-central to parietal cortex during encoding and maintaining of a haptic image, and (c) the central to parietal cortex during image transformation. A pronounced slow negative potential over the occipital cortex emerged only in the blind individuals and was time-locked to the processing epochs. Its amplitude increased with the amount of processing load. The slow wave effects observed in the blind individuals could indicate that occipital areas participate in specific, nonvisual functions or they could reflect a coactivation of these areas whenever the activation level of task-specific processing modules located elsewhere in the cortex is raised by nonspecific thalamocortical input.     

A Comparative Study of Activity and Dual Sensor: Activity and Minute Ventilation Pacing Responses to Ascending and Descending Stairs

Previous studies with activity-based rate; adaptive pacemakers have shown a somewhat paradoxical response when comparing ascending stairs to descending stairs. The objective of this investigation was to measure dual-sensor rate response provided by activity and minute ventilation (MV) compared with activity alone, and with a control group, during ascending and descending stairs. For dual sensor mode, measured mean peak pacing rate with 72 (92) steps per minute was 111 ± 13 beats/min (124 ± 14 beats/min) ascending stairs and 81 ± 7 beats/mm (97 ± 13 beats/min) for descending. For activity mode alone, mean peak pacing rate was 90 ± 12 beats/min (108 ± 19 beats/min) ascending stairs and 97 ± 12 beats/min (123 ±17 beats/min) descending. The mean peak control group heart rate ascending stairs for a step rate of 72 (92J steps/min were 116 ± 11 beats/min (127 ±14 beats/min) ascending stairs and for descending 89 ± 12 beats/min (95 ± 11 beats/min). While for dual sensor controlled pacing there was a significant difference for ascending and descending stairs at both step rates, there was no difference between going upstairs and downstairs for activity mode alone. Rates with dual sensor did not significantly differ from respective rates of the control group. The mean correlation coefficient between MV and paced rate was 0.85. Pacing heart rates delivered by the dual sensor mode were appropriate for ascending and descending stairs. In contrast to activity mode alone, the peak heart rates for dual sensor mode are higher during ascending than during descending stairs.