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Biomedical subjects

Koh Shingu

Publications and source records attributed to Koh Shingu.

50 records · Page 3Linked to original sources
PubMed2003

[NMDA receptor antagonist neurotoxicity and psychotomimetic activity].

Non-competitive NMDA receptor antagonists, in spite of their neuroprotective effects against neuronal ischemia, brain trauma, etc., cause neuronal damage in the rodent posterior cingulate and retrosplenial cortices (PC/RS), which are thought to be responsible brain regions for their psychotomimetic activity in humans. A number of anesthetics have not only GABAA receptor activating properties but also NMDA receptor antagonist properties. On the other hand, ketamine and nitrous oxide, both of which are potent non-competitive NMDA receptor antagonists and have little GABAA activating properties, are demonstrated to induce neuronal damage in the rat PC/RS. Furthermore, ketamine potentiates the neuronal damage by nitrous oxide. Although many anesthetics, such as halothane, isoflurane, barbiturates and benzodiazepines, inhibit the neuronal damage in the PC/RS by NMDA receptor antagonists, probably through GABAA receptor activation, we anesthesiologists should be aware of the risk of ketamine or nitrous oxide anesthesia, not to speak of the combined use of them, without using GABAA receptor activating agents.

Anesthetics, Dissociative↗
PubMed2003

[Anesthesia for laparoscopic cryptorchidpexy in a patient with congenital myopathy].

A relatively high incidence of malignant hyperthermia (MH) and an unpredicted (usually increased) sensitivity to muscle relaxants are reported in patients with congenital myopathies (CM). We present a case of anesthetic management of a patient with a clinical diagnosis of CM. An 18-month-old, 11.3-kg, male patient, who had received a diagnosis of CM, was scheduled for the laparoscopic cryptorchidpexy. Anesthesia was induced with propofol and fentanyl, and the trachea was intubated without muscle relaxants. An epidural catheter was inserted via the sacral hiatus, the tip of which was located at the second lumbar level for a purpose of obtaining not only pain relief but also muscle relaxation. Anesthesia was maintained with propofol, nitrous oxide and fentanyl, combined with epidural anesthesia. The anesthetic course was uneventful with enough pain relief and good muscle relaxation.

Anesthesia, Epidural↗
PubMed2003

[Comparison of analgesic effects of intravenous flurbprofen and suppository indomethacin after laparoscopic cholecystectomy].

BACKGROUND: Epidural analgesia may not be necessary after laparoscopic cholecystectomy, but analgesics, such as non-steroidal anti-inflammatory drugs, may often be required postoperatively. There have been only a few studies comparing different NSAIDs in this situation. METHODS: After laparoscopic cholecystectomy under general anesthesia using intravenous propofol, nitrous oxide and fentanyl 3 micrograms.kg-1, 40 patients were randomly allocated to receive either intravenous flurbprofen 50 mg or suppository indomethacin 50 mg. Visual analogue scales of postoperative pain at 0, 10, 20, 30 and 60 min after surgery (at rest and at coughing), use of rescue analgesics, and the presence or absence of complications were recorded. RESULTS: Pain score at rest was markedly reduced (> 15% reduction from the baseline value) in 13 of 20 patients after injection of flurbiprofen and in five patients after indomethacin during the initial 60 min after surgery (P < 0.05), whereas there was no significant difference between the two groups for the pain score during coughing. There was no difference in the need of rescue analgesics within the initial 60 min, but the flurbiprofen group required significantly more rescue analgesics than the indomethacin group during 1-24 h after surgery (P < 0.005). The incidence of complications was low in both groups. CONCLUSIONS: Compared with suppository indomethacin, intravenous flurbiprofen is more effective in acute postoperative pain but the duration of its analgesic effect is shorter.

Acute Disease↗
PubMed2002

Ketamine-induced c-Fos expression in the mouse posterior cingulate and retrosplenial cortices is mediated not only via NMDA receptors but also via sigma receptors.

Ketamine induces marked c-fos expression in the posterior cingulate and retrosplenial cortices (PC/RS). We investigated whether NMDA and/or sigma receptors were involved in the c-Fos expression. The number of Fos-LI positive boutons in NMDA receptor knockout mice was significantly lower than that in wild-type mice. Rimcazole but not haloperidol significantly suppressed the c-Fos expression. The results indicate that the ketamine-induced c-Fos expression is mediated not only via NMDA receptors but also via sigma receptors.

Animals↗
PubMed2002

Anticonvulsant effects of sevoflurane on amygdaloid kindling and bicuculline-induced seizures in cats: comparison with isoflurane and halothane.

PURPOSE: We compared the anticonvulsant effects of sevoflurane with those of isoflurane and halothane in amygdaloid kindling and bicuculline-induced seizures in cats. METHODS: In a crossover design, the effects of 70% nitrous oxide, and 0.3, 0.6, and 1.5 minimum alveolar concentration (MAC) of volatile anesthetics were studied in five cats in which the amygdala was electrically stimulated at the current used for establishing the kindled state. The effects of 0.6 and 1.5 MAC of volatile anesthetics were studied in another five cats, in which 0.2 mg.kg(-1) of bicuculline was administered i.v.. RESULTS: In the amygdaloid kindling model, all four anesthetics decreased the duration of after-discharge (AD), the rise of multiunit activity in midbrain reticular formation (R-MUA), and the behavior scores compared with findings without anesthetics. Halothane, at 1.5 MAC, significantly decreased the number of cats showing AD ( P < 0.05). In the bicuculline-induced seizure model, all five cats showed repetitive spikes during 1.5 MAC of sevoflurane, whereas only two and three cats, respectively, showed the repetitive spikes during 1.5 MAC of isoflurane and halothane. All three volatile anesthetics decreased the rise of R-MUA, the duration of the repetitive spikes, and the behavior scores. The suppression of the rise in R-MUA and the behavior scores with 1.5 MAC of sevoflurane was significantly less than that with 1.5 MAC of isoflurane. CONCLUSION: The anticonvulsant effects of sevoflurane were less potent than those of halothane in the amygdaloid kindling model and less potent than those of isoflurane in the bicuculline-induced seizure model.

Journal Article↗
PubMed2002

The inhibition of the N-methyl-D-aspartate receptor channel by local anesthetics in mouse CA1 pyramidal neurons.

UNLABELLED: Although the effects of local anesthetics on sodium channels and various other channels and receptors have been intensively investigated, there is little information available about their effects on N-methyl-D-aspartate (NMDA) receptors. We examined the effects of four local anesthetics (procaine, tetracaine, bupivacaine, and lidocaine) on NMDA-induced currents by using a whole-cell patch-clamp technique in dissociated mouse hippocampal pyramidal neurons. Procaine and tetracaine produced a reversible and concentration-dependent inhibition of NMDA-induced currents, but lidocaine showed little inhibition at 1 mM or less. The half-maximal inhibition values (mM; mean +/- SEM) for procaine, tetracaine, bupivacaine, and lidocaine at -60 mV were 0.296 +/- 0.031, 0.637 +/- 0.044, 2.781 +/- 0.940 (extrapolated data), and 7.766 +/- 14.093 (extrapolated data), respectively. Procaine 0.2 mM reduced the maximal NMDA-induced currents without affecting the 50% effective concentration values for NMDA. The inhibition by procaine exhibited voltage dependence and was more effective at negative potentials. These results indicate a noncompetitive antagonism of procaine on NMDA receptors and suggest that the inhibition is the result of a channel-blocking mechanism. IMPLICATIONS: We examined the effects of four local anesthetics (procaine, tetracaine, bupivacaine, and lidocaine) on NMDA-induced currents by using a whole-cell patch-clamp technique in dissociated mouse hippocampal pyramidal neurons. Both procaine and tetracaine produced a reversible and concentration-dependent inhibition of the NMDA-induced currents.

Anesthetics, Local↗
PubMed2002

[Fiberoptic tracheal intubation aided by jaw lifting in a patient with an epiglottic cyst].

Epiglottic cyst is known to cause difficult intubation. We report a patient with an epiglottic cyst whose trachea was successfully intubated with the aid of fiberoptic bronchoscopy combined with the jaw lift maneuver. A 29-year-old patient was scheduled for lumbar disk hernia surgery. On the first occasion, surgery was cancelled since the patient was unexpectedly found to have an epiglottic cyst and tracheal intubation was not possible. Two weeks later, nasotracheal intubation guided by fiberoptic bronchoscopy under conscious sedation was planned. On the first attempt of bronchoscopy, the glottic view was obscured by the cyst displacing the epiglottis posteriorly. Next, we applied the jaw lift maneuver in conjunction with bronchoscopy. The maneuver improved the glottic view by clearing the epiglottis from the posterior pharyngeal wall and the patient's trachea was successfully intubated. Jaw lifting could be a useful adjunct to fiberoptic bronchoscopy for tracheal intubation in patients with epiglottic cysts.

Adult↗
PubMed2002

[Anesthesia for a severe ankylosing spondylitis patient whose posture had been restricted to only sitting for over 20 years].

A 42-year-old woman with an Arnold-Chiari abnormality was scheduled for cervical spine surgery. She had severe ankylosing spondylitis, and all her joints from ankles to occipitocervical joint were fixed except hip joints, which had been replaced with artificial joints 20 years before. She could bend her upper body only in a range from -20 to 70 degree from the sitting position. Her posture had been restricted to only sitting for over 20 years, and she complained vertigo when positioned in supine position. The trachea was intubated with an aid of bronchofiberscopy under sedation in sitting position, and then anesthesia was induced with propofol and fentanyl. When she was turned to prone position, nasal bleeding was noticed and the surgery was performed in a modified sitting position. The intra- and post-operative course was uneventful. The present case indicates that long-term restriction only to sitting position modulates circulatory control in response to changing postures, and that preoperative evaluation for appropriate posture for surgery is mandatory.

Adult↗
PubMedDate not supplied

Airway management of a patient with tracheal stenosis for surgery in the prone position.

PURPOSE: When tracheal intubation is required in a patient with an uncollapsible tracheal stenosis, the tip of the tube is usually positioned proximal to the stenosis. Only the tip of the tube may be in the trachea and the tube can be dislodged. We report the successful airway management of a patient with an uncollapsible tracheal stenosis who underwent cranial surgery in the prone position. CLINICAL FEATURES: A 49-yr-old man with the saber-sheath trachea (stenosis of the entire intrathoracic trachea) was scheduled for a posterior fossa surgery for resection of a cerebellar tumour. Anesthesia was induced by allowing the patient to inhale spontaneously oxygen and increasing concentrations of sevoflurane up to 5%, without airway obstruction. After injection of vecuronium, an airway exchange catheter was inserted orally into the trachea. A laryngeal mask airway was then inserted with the exchange catheter in place and, with the aid of a fibrescope, a 6.0-mm reinforced tracheal tube was passed through the laryngeal mask into the trachea so that the tip of the tube was about 1 cm proximal to the stenosis. The patient was turned to the prone position and the operation proceeded uneventfully. CONCLUSIONS: The laryngeal mask and an airway exchange catheter were used as backups to tracheal intubation in this patient with tracheal stenosis in the prone position. Should the trachea be extubated accidentally, it may be re-intubated through the laryngeal mask and ventilation may be possible through the laryngeal mask or the exchange catheter.

Anesthetics, Inhalation↗
PubMedDate not supplied

Role of mitochondrial KATP channels and protein kinase C in ischaemic preconditioning.

1. Activation of mitochondrial KATP (mitoKATP) channels and protein kinase C (PKC) has been implicated in cardioprotective mechanisms of ischaemic preconditioning (IPC). However, the exact role of these events in early IPC remains unclear. 2. Isolated and perfused rat hearts underwent IPC with three cycles of 5 min ischaemia and 5 min reperfusion. The heart was subjected to 30 min global ischaemia followed by 120 min reperfusion. Flavoprotein oxidation was monitored to assess mitoKATP channel activity. Cardioprotection was evaluated by recovery of isovolumic left ventricular (LV) function and infarct size. 3. Diazoxide (50 mgr;mol/L) increased flavoprotein oxidation and conferred cardioprotection in a manner sensitive to the selective mitoKATP channel blocker 5-hydroxydecanoate (5-HD; 0.5 mmol/L). 4. Pretreatment with 0.5 mmol/L 5-HD abrogated IPC-induced flavoprotein oxidation and cardioprotection, whereas late treatment with 5-HD after IPC required a higher dose (2 mmol/L) to abolish flavoprotein oxidation and cardioprotection afforded by IPC. 5. Pretreatment with the PKC inhibitors Ro318425 (1 micro mol/L) and chelerythrine (5 micro mol/L) abolished IPC-induced flavoprotein oxidation and cardioprotection, whereas late treatment with Ro318425 required a higher dose (4 micro mol/L) to abolish flavoprotein oxidation and cardioprotection. 6. In conclusion, these results suggest that activation of mitoKATP channels is the trigger and the mediator of IPC and that PKC plays a crucial role in both phases of mitoKATP channel activation, although mitoKATP channels and PKC may be more activated during the mediator phase.

Animals↗