Biomedical subjects
Publications and source records attributed to K Shimoji.
Low-frequency (1.6-2.2 Hz) and weak-intensity electrical stimulation in the spinal extradural space produced complete to partial pain relief in a majority of patients (22 of 25) who suffered from intractable pain. Also it produced analgesia or hypoalgesia over a wide area of the body surface in 19 of the 25.
To determine whether neuronal firing is affected by anesthetics, the behavior of neurons in the mesencephalic reticular formation in response to repetitive somatosensory stimulation at 2/sec was studied during wakefulness and during nitrous oxide, halothane, and thiopental anesthesia in the cat. With clinical doses of the three anesthetics there were simultaneous blockades of both initial facilitation (28 of 32) and subsequent habituation (31 of 32) of the evoked responses in a majority of the mesencephalic reticular formation neurons. This dishabituation phenomenon was most prominent with thiopental and least prominent with nitrous oxide. Thus, it is suggested that progressive inactivation of not only the facilitatory process but also the inhibitory process in the neuronal activities of the mesencephalic reticular formation is associated with the so-called "anesthetic state" produced by these three anesthetics.
A simple gas chromatographic method for the determination of lidocaine in tissues is described. Lidocaine is extracted from the tissue samples using liquid nitrogen. The recoveries of lidocaine from brain, liver, and muscle were 98.6, 99.8 and 89.1%, respectively. Results were reproducible to within 1.0% of lidocaine administered.
The evoked spinal electrogram (SEG) in man was recorded from the epidural space, applying the technique of continuous epidural block, and compared with cord dorsum potential (CDP) in wakeful rabbits. Wave-form characteristics of the evoked SEG'S activated by the segmental nerves were almost the same in both cervical and lumbar regions. Somatosensory evoked response from the scalp was clearly demonstrated by stimulation of both the tibial nerve and fifth toe skin, whereas the evoked SEG was produced only by stimulation of the former. This finding might indicate that large nerve fibers are more responsible for producing the evoked SEG. Central latencies to the peaks of the second components of the P2 wave were 29 to 33 and 42 to 48 msec, in cervical and lumbar enlargements, respectively. This probably indicates the presence of a long feedback loop producing the second components. The amplitude of the N1 wave showed a steeper decline along the spinal cord than that of the P2 deflection, indicating between origins of these two components. Polarity of both the N1 and P2 waves became reversed when the recording electrode was situated in the anterior epidural space. The wave-form characteristics of the evoked SEG in man were very similar to those of the CDP in wakeful rabbits.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The slow positive wave (P2 wave) of the evoked spinal electrogram was recorded from the posterior epidural space in wakeful man, and studied by applying several modes of peripheral nerve stimulation. With graded stimulation the P2 wave amplitude rapidly reached the maximum at weaker stimulation than that required for the initially positive spikes (P1) and the preceding negative (N1) wave. The "second" component of the P2 appeared during stronger stimulation or during excitemenpt of the subjects. With prolonged repetitive stimulation the P2 wave increased its duration with several summits on the decaying phase. Two interactions were observed between the P2 waves produced by conditioning and testing stimulations in the same or different nerves: inhibition or occlusion by strong stimulation and faciliation by weak stimulation. Thus, the characteristic of the P2 wave in man was similar in part to that of the positive wave observed in decerebrate animals, and differnt in other ways presumably due to influences from supraspinal structures or species differences.
The evoked spinal electrogram (SEG) was studied in 11 patients with cervical spondylotic myelopathy or disc protrusion. All the patients were severely handicapped before surgery. The evoked SEG was classified in three grades before and during surgery. Periodic follow-up studies were done at 18 to 35 months, with an average of 24 months. Four of six patients were normal or slightly abnormal SEG recordings showed satisfactory improvement of the disability; however, only one patient showed any improvement when the recording was moderately or severely abnormal. Location of the cord lesion and type of surgery were similar in all patients examined, and the difference was likely ascribed to the physiological change of the intramedullary structures. The evoked SEG provides some information relative to the surgical treatment of spondylotic myelopathy or disc protrusion with cord lesion.
Explore the source record for details and available documents.
The slow positive (P2) wave of the evoked electrospinogram was recorded from the dorsal epidural space in man. The waveform characteristics of the P2 wave were similar to those of the dorsal cord positive wave (P wave), which is believed to be caused by the primary afferent depolarization (PAD) and to be related to presynaptic inhibitory action in animals. The "second" component of the P2 wave appeared during excitement or following strong stimulation and disappeared after thiamylal administration and during natural slow-wave sleep. The second component, also demonstrated in the P wave of rabbits during ketamine anesthesia, was abolished by spinal transection. Therefore, these second components in man and rabbits may originate from a feedback loop via supraspinal structures. Thus, supraspinal influences might play an important role in the regulation of presynaptic inhibition in the spinal cord of man during wakefulness and anesthesia.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.