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Biomedical subjects

K Shimoji

Publications and source records attributed to K Shimoji.

At least 181 records · Page 10Linked to original sources
PubMed1982

[Effects of lidocaine upon CCK-PZ and secretin producing paraneurons in the canine duodenum responding to luminal chemical stimuli (author's transl)].

Amino acid solution (50 mM tryptophan and 50 mM phenylalanine in saline) introduced into the canine duodenal loop causes an increased enzyme output from the pancreas, whereas administration of 0.1 N HCl into the duodenal loop causes an increased juice flow from the organ. Local anesthetic, lidocaine, introduced into the duodenal lumen suppressed the pancreatic enzyme releasing response to the intraluminal amino acid without affecting the juice flow response to the hydrochloric stimulus. Intravenously administered lidocaine did not block the pancreatic response to the intraluminal amino acid stimulus, suggesting that lidocaine affects the chemoreceptive, apical part of the endocrine cell or paraneuron which releases cholecystokinin-pancreozymin (CCK-PZ). Neither was the pancreas responding to an intravenous injection of CCK-PZ (5 Ivy Dog Units) suppressed by intravenously administered lidocaine even when its arterial concentration exceeded the convulsion level. This indicates that lidocaine affects the duodenal paraneurons recognizing the luminal stimuli but not the pancreatic cells responding to the hormones released by them. The results further suggest that in paraneurons as well as in neurons there seems to be a spectrum with regard to the susceptibility to anesthetics; thus the secretin releasing paraneuron is much more resistant to lidocaine than the CCK-PZ producing one.

Amino Acids↗
PubMed1982

Dorsal column stimulation in man: facilitation of primary afferent depolarization.

The effects of cervical epidural dorsal column stimulation on the negative and slow positive waves of the spinal cord potentials recorded from the posterior epidural space at the lumbar enlargement, in response to intense stimulation of the tibial nerve in five neurologically normal subjects during neuroleptanesthesia were studied. Single pulses applied to the cervical dorsal cord near the midline produced slow positive potentials preceded by negative waves in the dorsal spinal cord at the level of the lumbar enlargement. The negative wave, believed to represent synchronized activities of interneurons, was inhibited up to 100 to 120 msec by conditioning dorsal column stimulation. The slow positive wave, though to represent primary afferent depolarization, was facilitated for more than 100 msec with transient inhibitor for 10 to 40 msec. The results suggest that the pain-alleviating effect of dorsal column stimulation in man may be at least partly due to orthodromic and/or antidromic activation of descending inhibitory pathways which inhibit the responsible cells and facilitate primary afferent depolarization.

Adolescent↗
PubMed1981

Effects of diazepam on evoked electrospinogram and evoked electromyogram in man.

The effects of intravenous diazepam (0.2 mg/kg) on the evoked electrospinogram recorded with an epidural electrode in the posterior epidural space of the lumbar enlargement and on the evoked electromyogram recorded with disc electrodes on the gastrocnemius muscle were studied following posterior tibial nerve stimulation in 14 subjects. Following administration of diazepam, the amplitude of P1, and reflection of afferent input through the dorsal root, was significantly depressed 3 minutes after administration of diazepam. The amplitude of P2 of electrospinogram, a reflection of primary afferent depolarization in the spinal cord was significantly increased 10 to 30 minutes after injection. The amplitude of the H-reflex of the evoked electromyogram decreased significantly 3 to 30 minutes after injection, whereas that of the M-wave remained unchanged. These results suggest that diazepam in the clinical doses may directly affect function of the human spinal cord.

Adult↗
PubMed1979

Slow cord dorsum potentials elicited by descending volleys in man.

Human cord dorsum potential (CDP) was recorded from the posterior epidural space at the levels of cervical and lumbar enlargements, using epidural catheters as the recording electrodes, in 15 normal volunteers and six patients suffering from amyotrophic lateral sclerosis. In normal subjects the CDP elicited by descending volleys consisted of spike potentials followed by sharp negative and slow positive waves which were very similar to the P1, N1, and P2 potentials, respectively, of the CDP evoked segmentally. By contrast, in all patients with amyotrophic lateral sclerosis both the sharp negative and slow positive waves were absent in the CDP elicited by descending volleys, while the pattern of each component of the segmentally evoked CDP remained unchanged. Thus, the sharp negative and slow positive waves of human CDP elicited by descending volleys might reflect the activity of interneurones and primary afferent depolarisation respectively, produced by impulses through the corticospinal tract.

Adult↗
PubMed1978

Origin of somatosensory evoked responses recorded from the cervical skin surface.

Somatosensory evoked response from the cervical skin surface over the spine (the cervical SER) was recorded, and compared with the cord dorsum potential (CDP) simultaneously recorded from the posterior epidural space at the same segment. The cervical SER evoked by segmental nerve stimulation consisted of an initially positive spike (P1), the peak latency being the same as that of the P1 of the CDP, followed by a smaller negative wave with two peaks. The latency of the second peak of the negative wave (N1) coincided with that of the N1 of the CDP. Subsequent to this negative wave, a slow positive wave (P2) with peak latency similar to that of the P2 of the CDP, could be noticed in some subjects. The cervical SER could not be evoked even by strong stimulation of the cauda equina. Thus, the cervical SER might reflect a segmental phenomenon rather than the conducted potential along the cord, and originate from the spinal root and cord in the same way as the segmentally evoked CDP.

Adult↗