Search PubMed⌕ Search

Biomedical subjects

K Shimoji

Publications and source records attributed to K Shimoji.

At least 73 records · Page 4Linked to original sources
PubMed1997

[Oro-pharyngeal burn during electrodissection of the adenoid and tonsil].

We present a case of oro-pharyngeal burn which occurred during electrodissection of the adenoid and tonsil in a 5-year-old boy. We intubated the patient with an uncuffed spiral tube of appropriate size and noticed a slight gas leak during positive-pressure ventilation. Anesthesia was maintained with a mixture of 60% nitrous oxide, 40% oxygen and 2.5% sevoflurane. During manipulations of the right tonsil, orange-colored flame blew out about 5 cm from the mouth. Fortunately, the patient underwent the operative procedures without any further troubles, recovered fully from the grade 1 burn in the oral mucosa, and was discharged 23 days after surgery. The surgeons speculated that sevoflurane had been ignited. Although it is well known that sevoflurane is nonflammable in the concentration of clinical use, several reports show that sevoflurane is flammable in concentration of 10% under pure oxygen or nitrous oxide. We concluded that this accident was caused by electrocautery-induced ignition of the gauze packed into the larynx under a high concentration of oxygen which leaked through an uncuffed endotracheal tube. We have to bear in mind that any flammable substance may ignite when using electrocautery in a small space such as the mouth under oxygen-rich environment.

Adenoidectomy↗
PubMed1996

Thy-1-mediated phosphatidylinositol turnover in cultured rat glomerular mesangial cell.

Thy-1 glycoprotein is expressed in rat glomerular mesangial cells, and anti-Thy-1 nephritis induced by anti-Thy-1 antibodies is a model of human renal diseases. In this study, we examined Thy-1-mediated biological reactions in cultured rat glomerular mesangial cells utilizing two anti-Thy-1 monoclonal antibodies (mAbs), 1-22-3 and OX-7. Incubation of the cells with these mAbs resulted in increased inositol trisphosphate (IP3) levels. The rise in IP3 produced by mAb 1-22-3 was greater than that produced by mAb OX-7 at the same dose. Incubation of mesangial cells with these mAbs resulted in an increase in the intracellular free calcium concentration ([Ca2+]i). mAb 1-22-3 induced a sustained increase in [Ca2+]i, while that induced by mAb OX-7 lasted 1-2 min, then decreased to the basal level. An transient increase in [Ca2+]i was also observed in Ca(2+)-free medium, indicating that these [Ca2+]i increases are due to release of Ca2+ from internal stores by IP3 without calcium flux across cell membrane. When cells were pretreated with protein tyrosine kinase (PTK) inhibitors (herbimycin A or genistein), Thy-1-mediated increases in [Ca2+]i were inhibited. These data suggest that Thy-1 induces the production of IP3 (including inositol 1,4,5-triphosphate, an intracellular Ca(2+)-releasing factor) and that PTKs may contribute to the Thy-1-mediated elevation of [Ca2+]i which presumably results from phospholipase C activation following Thy-1-mediated signaling in rat mesangial cells.

Animals↗
PubMed1996

Spinal tracts producing slow components of spinal cord potentials evoked by descending volleys in man.

Slow negative (N) and slow positive (P) waves are frequently produced in the posterior epidural space at the lumbosacral enlargement by epidural stimulation of the rostral part of human spinal cord. The production of these slow potentials are thought to be responsible for analgesia at the stimulated segment as well as below that level. In order to define the spinal tract which mediates these slow potentials, we stimulated directly or from the epidural space the dorsal, dorsolateral, lateral and ventral columns at the cervical or thoracic level, and epidurally recorded spinal cord potentials (des.SCPs) at the lumbosacral enlargement in 7 patients who underwent spine or spinal cord surgery. The des.SCPs recorded in the lumbosacral enlargement consisted of polyphasic spike potentials followed by slow N and P waves. At a near threshold level of stimulus intensity the slow N and P potentials were consistently elicited only by stimulation of the dorsal column. The slow waves were also produced by intense stimulation of other tracts, but remained significantly (P < 0.05 - P < 0.01) smaller than those evoked by dorsal column stimulation when compared at the same stimulus intensity. Moreover, the slow P wave could not be elicited even by intense stimulation (10 times the threshold strength for the initial spike potentials) of the ventral column. Thus, the results suggest that the slow N and P waves are mostly mediated by the antidromic impulses descending through the dorsal column.

Adult↗
PubMed1996

Somatosensory evoked potentials recorded from the posterior pharynx to stimulation of the median nerve and cauda equina.

Somatosensory evoked potentials (ppSEPs) in response to stimulation of the median nerve at the wrist and the cauda equina at the epidural space (the L4 level) were recorded from the posterior wall of the pharynx in 15 patients who underwent spinal surgery under general anesthesia, using disc electrodes attached to the endotracheal tube, and compared with segmental spinal cord potentials (seg-SCPs) that were recorded simultaneously from the posterior epidural space (PES). ppSEPs consisted of the initially positive spike (P9) followed by slow positive (P13) and negative (N22) waves. The P13 and N22 of ppSEPs had phase reversal relationship with the P2 and N2 recorded from the PES, respectively. The peak latencies of P9 (9.40 +/- 0.7 ms) (mean +/- SD), P13 (13.1 +/- 0.9 ms), and N22 (22.0 +/- 2.1 ms) of ppSEPs coincided with those of P1, N1 and P2 of seg-SCPs, respectively, ppSEPs were recorded more clearly with a reference electrode on the dorsal surface of the neck than with the reference electrode at the earlobe or back of the hand. The threshold and maximal stimulus intensities were also similar between the ppSEPs and seg-SCPs. Thus, the P9, P13, and N22 components of ppSEPs were thought to have the same origin as the P1, N1 and P2 of seg-SCPs, respectively. Therefore, the P9, P13 and N22 of ppSEPs may reflect incoming volleys through the root, synchronized activities of the interneurons and primary afferent depolarizations (PAD), respectively. ppSEPs in response to cauda equina stimulation showed that the latencies of the two initial components (4.6 +/- 0.4 and 6.4 +/- 0.6 ms) corresponded to those of the SCPs recorded from the PES (4.6 +/- 0.3 and 6.3 +/- 0.5 ms), suggesting that these potentials reflect impulses conducting through the spinal cord, similar to epidurally recorded SCPs.

Adult↗
PubMed1996

Central nuclei and spinal pathways in feedback inhibitory spinal cord potentials in ketamine-anaesthetized rats.

It has been suggested that heterosegmentally activated slow positive potentials (HSP), recorded from the spinal cord of rat and humans, are feedback inhibitory potentials. The present study was carried out to define ascending and descending spinal tracts and the sites of central nuclei involved in the production of these HSP, and the effects of ketamine on these central nuclei. The spinal cords in ketamine-anaesthetized rats were transected to determine the ascending and descending tracts involved in the production of hindpaw (HP) and forepaw (FP) HSP, respectively. Lesions of the brain at various levels were performed stereotactically during ketamine anaesthesia. Dorsal one-third resection of the cord at the T8-9 level did not affect HSP significantly, while contralateral lesion of the dorsal two-thirds of the cord decreased FP-HSP but not HP-HSP during ketamine. Bilateral transection of the ventral one-third of the cord abolished both HSP. Ablation of the cerebral cortex, cerebellum, thalamus, midbrain and pons did not affect HSP significantly. However, transection of the middle medulla decreased, while transection of the most caudal part of the medulla completely abolished both HSP. Ketamine decreased HSP even in the medulla-spinal cord preparation and the segmental slow positive wave in spinalized animals. In ketamine-anaesthetized rats, ascending and descending spinal tracts involved in the production of HP-HSP and FP-HSP are located bilaterally in the ventrolateral quadrant and in the contralateral lateral funiculus and ventrolateral quadrant, respectively. Principal central nuclei feeding back HSP might be situated diffusely in the medulla down to the caudal part. Ketamine is suggested to suppress these inhibitory feedback potentials predominantly at, and partly even below, the level of the medulla.

Anesthetics, Dissociative↗
PubMed1996

The effects of halothane on arginine-vasopressin-induced Ca2+ mobilization from the intracellular stores and the receptor-mediated Ca2+ entry from the extracellular space in single cultured smooth muscle cells of rat aorta.

Halothane has a direct action on vascular smooth muscle cells and causes relaxation of these cells, yet neither the mechanism nor the site of its action is completely understood. Using digital imaging microscopy with the Ca2+ indicator fura-2, the effects of halothane on the intracellular [Ca2+] dynamics induced by arginine vasopressin (AVP) in the perinuclear region and cytosol in single cultured smooth muscle cells of rat aorta were studied. Changes in intracellular [Ca2+] were expressed as percent increases in the ratios of fluorescence intensity at 500 nm excited by 340 nm and 380 nm. AVP (10(-7) M) elicited an initial transient increase in [Ca2+] in the perinuclear region higher than that in the cytosol in Ca(2+)-containing solution (346% +/- 21% and 213% +/- 22%, respectively). Halothane, 0.5%, attenuated the [Ca2+] increase induced by AVP in the perinuclear region and cytosol, and halothane, 1.0% and 2.0%, abolished the differential increase. Under the continuous application of AVP (10(-7) M), Ca2+ restoration in the medium after perfusion with Ca(2+)-free solution increased the perinuclear [Ca2+] more than the cytosolic [Ca2+]. Both were significantly attenuated by 2.0% halothane, but not by nicardipine (10(-5) M) or ryanodine (10(-6) M). Our results suggest that halothane may attenuate the Ca2+ release from the intracellular Ca2+ stores more than the receptor-mediated Ca2+ entry from the extracellular space in the AVP-induced response in these cells.

Anesthetics, Inhalation↗
PubMed1996

Regionally different elevation of intracellular free calcium in hippocampus of septic rat brain.

The effect of sepsis on cellular calcium homeostasis in the central nervous system (CNS) was investigated using hippocampal slices of rats in which sepsis was induced by cecal ligation and puncture (CLP). Hippocampal slices were prepared from septic or sham-operated rats at 24 h after abdominal surgery. The basal intracellular calcium ([Ca2+]i) and its response to oxygen-glucose deprivation in hippocampal slices were measured for assessing cellular calcium homeostasis using fura-2 fluorescent imaging technique. The levels of [Ca2+]i were estimated by the fluorescence ratio (R340/380). Twenty-four hours after CLP, spontaneous movement was reduced and plasma lactate was increased in the septic rats in comparison with the sham-operated rats in which laparotomy was performed without CLP. Basal level of R340/380 in the CA4 ara (.72 +/- .07) was significantly higher (p < .001) in the septic group than that in the sham-operated group (.55 +/- (.06). The fluorescence ratio of septic vs. sham-operated in other hippocampal regions were .55 +/- .09 vs. .48 +/- .06 in CA1 (not significant) and .65 +/- .10 vs. .59 +/- .08 (not significant) in CA3, respectively. Increase in [Ca2+]i due to oxygen-glucose deprivation was significant in CA1 and CA3 of the septic group and in all hippocampal regions of sham-operated group. However, it was not significantly increased in CA4 of the septic group. These results suggest that regional deregulation of cellular calcium occurs in the CNS following CLP. Cellular calcium deregulation may be one of the pathogeneses occurred in clinically observed septic encephalopathy.

Animals↗
PubMed1996

[Paraplegia following coeliac plexus block by anterior approach under direct vision].

We report here a case of paraplegia following coeliac plexus block by anterior approach under direct vision. Laparotomy was performed in a 62-year-old male patient with pancreatic cancer. Coeliac plexus block was undertaken in order to control his back pain, since the tumor was unresectable. The patient complained of numbness and weakness of his legs 14 hours later. The consequence of neurological events was diagnosed as ischemic infarct of the spinal cord by myelo-CT and MRI. He died of pancreatic cancer without recovery of neurological disturbances 4 months after the surgery. As demonstrated in this case, even when coeliac plexus block was performed by open anterior approach under direct vision, paraplegia might be a possible complication due to the anatomical proximity of coeliac plexus to the Adamkiewicz's artery.

Autonomic Nerve Block↗
PubMed1995

The sensitivity of AMPA-selective glutamate receptor channels to pentobarbital is determined by a single amino acid residue of the alpha 2 subunit.

Clinical concentrations of pentobarbital inhibit the alpha-amino-3-hydroxy-5- methyl-4-isoxazole propionic acid (AMPA)-selective glutamate receptor (GluR) channels. Recently, the AMPA-selective GluR channels that contained the alpha 2 subunit were shown to be more sensitive to pentobarbital block than those without the alpha 2 subunit. Here we demonstrated that replacement by glutamine of the arginine residue in putative transmembrane segment M2 of the alpha 2 subunit (mutation alpha 2-R586Q) drastically reduced the pentobarbital sensitivity of the alpha 2 heteromeric channel to the level comparable to those of the alpha 1 and alpha 2-R586Q homomeric channels. These results suggest that the arginine residue in segment M2 of the alpha 2 subunit is the critical determinant of the sensitivities of the AMPA-selective GluR channels to pentobarbital.

Amino Acid Sequence↗
PubMed1995

Role of A delta afferent fibers in modulation of primary afferent input to the adult rat spinal cord.

To address the question of whether fine myelinated and unmyelinated primary afferent fibers contribute to the mechanism of presynaptic inhibition in the spinal cord, we studied dorsal root-evoked dorsal root potentials (DR-DRPs) using a newly developed longitudinal spinal cord slice preparations in the adult rat. Single stimuli applied to the L6 dorsal root elicited a DR-DRP in the L5 dorsal root which had an amplitude of 50-150 microV and had a half decay time of 20-66 ms. The DR-DRP was depressed by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10-20 microM), while DL-2-amino-5-phosphonovaleric acid (APV, 50-100 microM) had no significant effect. DR-DRP was markedly depressed by bicuculline or picrotoxin. The evoked DR-DRP was unchanged in rats treated with capsaicin which eliminated the majority of unmyelinated C afferent fibers. Taken together with the higher voltages (> or = 1.9 V) required to elicit DR-DRP, this observation strongly suggests that the A delta afferent fibers are primarily responsible for producing and receiving the DR-DRP. The present study shows that the DR-DRP mediated by the A delta fibers in the slice preparation is analogous to those described for larger myelinated fibers in vivo. This pathway may contribute importantly to synaptic modulation of somatosensory information, including nociception at the superficial dorsal horn through an interneuronal connection which are mediated by the non-NMDA and GABAA receptors.

Afferent Pathways↗
PubMed1995

Effects of propofol on various AMPA-, kainate- and NMDA-selective glutamate receptor channels expressed in Xenopus oocytes.

Effects of a general intravenous anesthetic 2,6-diisopropylphenol (propofol) on various glutamate receptor (GluR) channels were examined on the alpha 1 and alpha 1/alpha 2 GluR channels selective for alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), the beta 2/gamma 2 GluR channels selective for kainate, and the epsilon 2/zeta 1 and epsilon 3/zeta 1 N-methyl-D-aspartate (NMDA) receptor channels expressed in Xenopus oocytes. Propofol suppressed the current responses of the alpha 1/alpha 2, beta 2/gamma 2, epsilon 2/zeta 1 and epsilon 3/zeta 1 channels in a dose-dependent manner, whereas it enhanced the current responses of the alpha 1 channel. The extents of inhibition were in the order epsilon 2/zeta 1 > epsilon 3/zeta 1 > beta 2/gamma 2 > alpha 1/alpha 2 channels. During perfusion of 500 microM propofol, the alpha 1/alpha 2, beta 2/gamma 2, epsilon 2/zeta 1 and epsilon 3/zeta 1 channels were progressively suppressed. Furthermore, 10 min perfusion of 20 microM propofol inhibited the epsilon 2/zeta 1 channel by 24%. These results suggest that clinical concentrations (approximately 35 microM) of propofol suppress the NMDA receptor channels slightly.

Animals↗
PubMed1995

Relationship between tissue ischemia and venous endothelin-1 during abdominal aortic aneurysm surgery.

OBJECTIVES: Several substances may be released from ischemic tissues with the declamping shock that occurs during abdominal aortic aneurysm surgery. To clarify the relationship between tissue ischemia and venous endothelin-1 (ET-1) level in humans, plasma ET-1 and oxygen content in the iliac vein were measured before anesthesia, after the induction of anesthesia, after the release of the proximal and first distal clamps, after the release of the second distal clamp, and 1 hour after the second clamping. DESIGN: Prospective study. SETTING: A University hospital. PARTICIPANTS: Seven patients who underwent abdominal aneurysmectomy and replacement with bifurcated graft. INTERVENTIONS: A 20G catheter was inserted into the radial artery for the direct measurement of blood pressure and for collecting arterial blood. An 18G, 20-cm catheter was inserted into the femoral vein for collecting venous blood from the lower extremities. MEASUREMENTS AND MAIN RESULTS: The arterial and venous ET-1 levels did not change after the induction of anesthesia. Immediately after the initial release of the proximal and distal clamps, venous oxygen content dramatically decreased from 11.3 to 3.6 mL/dL (vol%) with significant increases in venous ET-1 concentration from 2.3 to 4.9 pg/mL. Concomitant with the decrease in venous oxygen content, venous plasma pH and base excess decreased with increase in PCO2, suggesting that ischemic changes in tissues distal to the cross-clamp may occur during aortic clamping. Venous ET-1 levels were significantly correlated with venous oxygen content, pH, PO2, oxygen saturation, base excess, blood sodium concentration, and potassium concentration. One hour after the second declamping, the venous ET-1 level remained high in comparison with the preanesthetic level, whereas the venous oxygen content returned to the preanesthetic level. There was no correlation between venous plasma ET-1 and venous plasma norepinephrine or epinephrine concentration. CONCLUSIONS: Tissue ischemia may increase venous ET-1 levels in humans. Factor(s) other than tissue ischemia may provoke the increase in venous ET-1 that occurs after the release of the second distal clamp.

Aged↗
PubMed1995

Aortic aneurysm in a four-year-old child with tuberous sclerosis.

We present a case of aortic aneurysm in a four-year-old child complicated with tuberous sclerosis. We used the same general principles as for adult patients and successfully managed our patient. Our methods included the use of isoflurane plus epidural anaesthesia, dopamine to maintain blood pressure, and induced mild hypothermia to reduce brain metabolism and to prevent spinal cord damage during aortic cross-clamping. Intensive monitoring including EEG was beneficial to the anaesthetic management.

Anesthesia, Epidural↗
PubMed1995

[Brain death committees of university hospitals in Japan].

We carried out a questionnaire survey on the brain death committees of university hospitals in Japan. Fewer than a half of university hospitals have independent brain death committees. However, a tendency was observed from this survey that the university hospitals established independent brain death committees from the pre-existing ethical committees. The role of anesthesiologists seems to become more important for decision of the brain death.

Anesthesiology↗
PubMed1995

[Anesthetic management for bronchofiberscopy and esophageal mannometric study in a patient with CHARGE association].

Bronchofiberscopy and esophageal mannometric study were scheduled for a CHARGE association patient who complained respiratory distress and dysphagea after PDA ligation. We carried out both tracheal intubation and LMA insertion twice. LMA insertion was performed smoothly, but mask holding and tracheal intubation were very difficult. CHARGE association is a rare multiple anomaly, and presents some problems for anesthetic management. Especially, we have to consider the difficult airway management in such a patient.

Abnormalities, Multiple↗
PubMed1995

[Prolonged muscle paralysis after long-term infusion of muscle relaxants and large doses of steroids].

We have recently encountered three patients who developed prolonged muscle paralysis after long-term infusion of muscle relaxants and administration of large doses of steroids. Among many factors implicated in the cause of this paralysis, steroids and muscle relaxants were suggested to be most likely causative agents. In order to avoid such muscle paralysis, we must be careful to limit the dose of relaxants as small as possible. For this purpose, monitoring of neuromuscular blockade is indispensable.

Female↗