Imaging of a coimmobilized diaphorase and albumin surface was investigated by scanning electrochemical microscopy (SECM) with shear force based tip-substrate distance control. A microelectrode tip was attached to a commercially available tuning fork to detect the shear force between the microelectrode tip and the surface. We used the standing approach mode, which repeats an approach and retraction at each data point of the surface to obtain simultaneous current and topographic images. To check the performance of our SECM system, we imaged a platinum-patterned array electrode and a diaphorase/albumin coimmobilized glass surface. Since the system acquires current when the tip is retracted to a desired distance, this mode is useful for a relatively large microelectrode (approximately 10 microm) and for scanning a large area (few hundreds of micrometers). Furthermore, by retracting the tip when the tip moves laterally to the next data point to avoid contact between the tip and sample surface, we successfully imaged the surface without destroying its morphology.
We have reported that DCS (dorsal column stimulation) improves the clinical symptoms of cases in persistent vegetative states. Since then, we have accumulated 23 cases who have been treated by DCS. We describe the clinical EEG, rCBF, and biochemical changes in cerebrospinal fluid (CSF) caused by DCS in patients in persistent vegetative states: (1) eight of these cases showed good clinical improvement; (2) most patients were young and the CT scan did not show large, diffuse, definite or bilateral low density areas in cortex, brainstem of thalmus; (3) neurostimulation increased rCBF (cerebral blood flow) in many parts of the brain in cases with vegetative states; blood flow increased in the cerebrum, cerebellum and brainstem; (4) neurostimulation enhanced the metabolism of catecholamines in CSF, NE, DA, DOPAC, HVA, and 5HIAA increased, but 3MT and 5HT decreased in CSF. DCS increased rCBF, enhanced the metabolism of catecholamines in CSF, and improved the EEG in patients in persistent vegetative states.
Dorsal column stimulation has been used in four patients who were in a persistent vegetative state. There was improvement of the EEG in four patients and clinical improvement in three patients. Stimulation was for 12 hours per day at 100 Hz, 5 to 8 volts, and with a pulse width of 0.12 msec. The mechanism of improvement may involve changes in cerebral blood flow.
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