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K Omote

Publications and source records attributed to K Omote.

At least 19 recordsLinked to original sources
PubMed2001

Involvement of capsaicin-sensitive fibers in spinal NMDA-induced glutamate release.

The activation of spinal NMDA receptors can evoke glutamate release through the production of nitric oxide (NO) within the spinal cord, resulting in pain-relating behavior. In this study, we investigated the involvement of capsaicin-sensitive primary afferents in this phenomenon using in vivo intrathecal microdialysis. Intrathecal NMDA perfusion evoked increases in the concentrations of NO metabolises and glutamate and in pain-related behavior in both neonatal capsaicin and vehicle-treated rats. Although the degrees of increase in NO metabolises in capsaicin- and vehicle-treated rats were not significantly different, capsaicin-treated rats showed significantly smaller increases in glutamate concentration and pain-related behavior than did vehicle-treated rats. Our results showed that glutamate release from capsaicin-sensitive primary afferent terminals is involved in spinal NMDA-induced pain.

Animals↗
PubMed2001

Peripheral nitric oxide in carrageenan-induced inflammation.

Recent studies have suggested that nitric oxide (NO) peripherally produced by different nitric oxide synthase (NOS) isoforms contributes to edema formation and development of hyperalgesia. The present study was designed to examine the effects of NOS isoforms on NO release in carrageenan-induced inflammation at various time points. A microdialysis probe was implanted subcutaneously into the glabrous skin of hindpaws of Sprague-Dawley rats under pentobarbital anesthesia. After sample collection to obtain the basal level of the total amount of nitrite and nitrate (NO2-/NO3-), modified Ringer solution, a non-selective NOS inhibitor, NG monomethyl-L-arginine acetate (L-NMMA), or an iNOS inhibitor, aminoguanidine hemisulfate (AG) was perfused through the microdialysis probe. 2 mg of carrageenan was injected into the plantar surface of the probe-implanted hindpaw. Carrageenan was also injected in rats that had undergone sciatic nerve sectioning. Carrageenan significantly increased the dialysate concentrations of NO2-/NO3- for more than 8 h. L-NMMA suppressed the carrageenan-induced increase in NO2-/NO3- concentration. Although AG did not suppress the increase in NO2-/NO3- for the first 2 h after carrageenan injection, significant suppression of the increase in NO2-/NO3- was observed from 2.5 h after carrageenan injection. In the rats in which the sciatic nerves had been denervated, the increases in concentrations of NO2-/NO3- were completely suppressed up to 3 h and partially suppressed 4.5-8 h after carrageenan injection. The results of the current study show that carrageenan induces peripheral release of NO, the production of which is mediated by nNOS in the early phase and by both nNOS and iNOS in the late phase of carrageenan-induced inflammation.

Animals↗
PubMed2001

Acute respiratory and metabolic acidosis induced by excessive muscle contraction during spinal evoked stimulation.

Spinal somatosensory evoked potentials (SSEPs) have been used to monitor spinal cord function during corrective scoliosis surgery. We report three cases in which direct epidural stimulation for measurement of SSEPs produced paraspinal muscle contraction, resulting in respiratory and metabolic acidosis. In two of the cases, SSEP-induced acidosis was observed even when only the first twitch of the train-of-four response was detectable after a second dose of muscle relaxant. In one of these two cases, the acidosis was abolished after a sufficient dose of vecuronium to ablate the twitch response. To prevent SSEP-induced respiratory and metabolic acidosis, we recommend that SSEPs should be measured only when profound neuromuscular blockade has been obtained.

Acidosis↗
PubMed2001

The effects of peripheral administration of a novel selective antagonist for prostaglandin E receptor subtype EP(1), ONO-8711, in a rat model of postoperative pain.

UNLABELLED: Mechanically evoked pain, also known as incident pain, induced by coughing or deep breathing after surgery leads to potentially devastating consequences. It is generally thought that the prostaglandin receptor- (especially, the receptor for prostaglandin E(2), EP receptor) mediated sensitization of sensory nerve fibers is a key contributor to the generation of hyperalgesia. We examined whether a peripherally administered novel selective EP(1) antagonist, ONO-8711, would be a potential analgesic for incision-induced mechanical hyperalgesia. We used a rat model of postoperative pain introduced by Brennan et al. (1). Withdrawal thresholds to punctate stimulation and response frequencies to nonpunctate mechanical stimulation were determined by using von Frey filaments applied adjacent to the wound and directly to the incision site of the hind paw, respectively. Mechanical hyperalgesia to punctate and nonpunctate stimuli was observed 2 and 24 h after the incision. ONO-8711 (2, 10, or 50 microg) or saline was administered subcutaneously into the hind paw on the ipsilateral side to the incision. ONO-8711 significantly (P < 0.01) increased the withdrawal thresholds to punctate mechanical stimulation and significantly (P < 0.01) decreased the response frequencies to nonpunctate mechanical stimulation in a dose- and time-dependent manner 2 and 24 h after the incision. We conclude that EP(1) receptor-mediated sensitization of sensory nerve fibers may contribute to the generation of mechanical hyperalgesia produced by incisional surgery, and that the EP(1) receptor antagonist ONO-8711 may be an option for treatment of postoperative pain, especially incident pain. IMPLICATIONS: The peripheral administration of an antagonist for EP(1) receptor that is a subtype of prostaglandin E receptors can inhibit the mechanical hyperalgesia induced by a surgical incision.

Animals↗
PubMed2001

[The effect of continuous intra-articular and intra-bursal infusion of lidocaine on postoperative pain following shoulder arthroscopic surgery].

We evaluated the effects of continuous intra-articular and intra-bursal infusion of lidocaine on postoperative pain following shoulder arthroscopic surgery. Forty-one ASA I-II patients scheduled for shoulder arthroscopic surgery, were allocated into following four groups. The patients, after intra-articular arthroscopic surgery, either received intra-articular lidocaine (Group I, n = 10) or did not (Group III, n = 10). The patients after extra-articular arthroscopic surgery either received intra-bursal lidocaine (Group II, n = 11) or did not (Group IV, n = 10). Group I and Group II received 8 ml of 1% lidocaine intra-articularly and intra-bursally, respectively, at the end of surgery, followed by continuous infusion of 1% lidocaine at the rate of 2 ml.hr-1 for 24 hours. The intensities of postoperative pain were evaluated by Visual Analogue Scale (VAS), 2, 5, 8, 12, 18 and 24 hours after surgery, and by the number of patients' request for supplemental analgesic for 24 hours. The VAS scores and the number of analgesic requests were significantly lower (P < 0.05) in Group I than Group III, and in Group II than Group IV throughout the postoperative observation period. No adverse effects were observed during this study. We conclude that continuous intra-articular and intra-bursal infusion of lidocaine provides effective postoperative pain relief for shoulder arthroscopic surgery.

Adult↗
PubMed2000

A comparison of hemodynamic changes after endotracheal intubation by using the lightwand device and the laryngoscope in normotensive and hypertensive patients.

We compared the effects of the lightwand technique on hemodynamic responses, time-to-intubation, number of attempts, and complications during tracheal intubation with those of direct-vision laryngoscopy in normotensive (LN and TN group; n = 20, respectively) and hypertensive (LH and TH group; n = 20, respectively) patients. Lightwand or laryngoscopic oral endotracheal intubation was performed after the induction of anesthesia with fentanyl and propofol and muscle relaxation with vecuronium. Systolic blood pressure, diastolic blood pressure, and heart rate were recorded, and the change from "before intubation" to "immediately after intubation" (DeltaP) in each variable was calculated. In normotensive patients, significantly larger DeltaP in systolic blood pressure was observed in the LN group than in the TN group (P < 0. 05). In hypertensive patients, there were no significant differences between the LH group and the TH group in DeltaP after intubation. The time-to-intubation and number of attempts in the lightwand groups were significantly longer and more frequent than those in the laryngoscope groups (P < 0.05). The number of patients who complained of hoarseness was larger in the lightwand groups than in the laryngoscope groups (P < 0.05). We conclude that the lightwand technique significantly attenuates hemodynamic changes after intubation in comparison with the laryngoscopic technique in normotensive patients. However, in hypertensive patients, there is no difference in hemodynamic changes between the two techniques.

Anesthesia↗
PubMed2000

Activation of peripheral NMDA-nitric oxide cascade in formalin test.

BACKGROUND: It has been suggested that peripheral glutamate and nitric oxide (NO) released by tissue-damaging stimuli play an important role in peripheral nociceptive transmission. This study was conducted to determine whether NO was released in the periphery after subcutaneous injection of formalin and whether the peripheral N-methyl-d-aspartate (NMDA)-NO cascade was activated. METHODS: During pentobarbital anesthesia, a microdialysis probe was implanted subcutaneously into the glabrous skin of both hind paws of Sprague-Dawley rats. After sample collection to obtain the basal level of NO metabolites (total amount of nitrite [NO2-] and nitrate [NO3-] [NO2--NO3-]), 5% formalin was injected into the plantar surface of the right hind paw during perfusion of the dialysis catheters with artificial cerebrospinal fluid (ACSF), the NO synthase inhibitor NG-monomethyl-L-arginine acetate, or the NMDA antagonist D,l-2-amino-5-phosphonovaleric acid through a microdialysis probe. Formalin also was injected in the animals that underwent sciatic nerve sectioning. In another series of experiments, NMDA was perfused through one probe. Samples for measurement of NO2--NO3- were collected and immediately analyzed using high-performance liquid chromatography. RESULTS: Subcutaneous formalin significantly increased the dialysate concentrations of NO2--NO3- (maximum increase 144 +/- 12% of baseline value 30 min after formalin administration; P < 0.05) on the side ipsilateral to the injection. Both NG-monomethyl-l-arginine acetate and D, l-2-amino-5-phosphonovaleric acid significantly (P < 0.05) suppressed the formalin-induced increases in NO2--NO3- concentration. In the rats with denervation of the sensory nerves, formalin did not change the NO2--NO3- concentration. In addition, NMDA perfusion significantly (P < 0.05) increased the concentrations of NO2--NO3-. CONCLUSION: The results of the current study show that subcutaneous formalin injection induces peripheral release of NO, the production of which is mediated by activation of NMDA receptors in the peripheral nervous system.

Animals↗
PubMed2000

Analgesic mechanisms of ketamine in the presence and absence of peripheral inflammation.

BACKGROUND: The studies on the mechanisms of ketamine antinociception have led to conflicting results. In this study, the authors investigated the contribution of supraspinal monoaminergic descending inhibitory system to ketamine analgesia for acute nociception and inflammation-induced hyperalgesia. METHODS: Male Sprague-Dawley rats were used. The paw withdrawal latencies to radiant heat stimuli were measured to assess the thermal nociceptive threshold. The analgesic effects of intrathecal or intraperitoneal ketamine were examined in the rats that received unilateral intraplantar carrageenan and in those that were untreated. In addition, it was examined whether pretreatment with intrathecal yohimbine or methysergide inhibited the analgesic effects of ketamine. Using an intrathecal microdialysis method, noradrenaline and 5-hydroxytryptamine concentrations in lumbar cerebrospinal fluid were measured after intraperitoneal ketamine in both saline- and carrageenan-treated rats. RESULTS: In the untreated rats, intraperitoneal but not intrathecal ketamine produced antinociceptive effects in a dose-dependent manner. Pretreatment with intrathecal yohimbine or methysergide inhibited these antinociceptive effects. Intraplantar carrageenan significantly reduced paw withdrawal latencies on the injected paw but not on the contralateral paw. Both intraperitoneal and intrathecal ketamine reversed the shortened paw withdrawal latencies on the injected side in a dose-dependent manner without any effects on the contralateral side. Neither yohimbine nor methysergide inhibited these antihyperalgesic effects. In analyses of monoamines, the magnitude of increase in monoamines after intraperitoneal ketamine was significantly smaller in the carrageenan-treated rats than in the saline-treated rats. CONCLUSION: These results demonstrated that ketamine produced antinociceptive effects through an activation of the monoaminergic descending inhibitory system, whereas, in a unilateral peripheral inflammation-induced hyperalgesic state, the monoaminergic system did not contribute to the antihyperalgesic effects of ketamine. The mechanisms of the antinociceptive and antihyperalgesic properties of ketamine are different.

Adrenergic alpha-Antagonists↗
PubMed2000

[Clinical evaluation of accuracy of a new disposable pump (Syrinjector) for continuous epidural infusion].

We evaluated the accuracy of a new disposable pump (Coopdech Syrinjector), which employed the negative pressure made by injecting fluid into the pump for continuous epidural infusion. Thoracic epidural catheter was placed at the T6-T8 level prior to the lung surgery. The continuous epidural infusion of 0.25% bupivacaine at 2 or 3 ml.h-1 was started immediately after the surgery. The residual volume of bupivacaine was recorded. From our results, the injection speed of Syrinjector was satisfactory for clinical use of continuous epidural infusion of bupivacaine. However, when this pump is reused or the volume of the residual local anesthetics is less than 10 ml, the infusion accuracy will be potentially imprecise.

Analgesia, Epidural↗
PubMed2000

Altered expression of beta-catenin and c-erbB-2 in early gastric cancer.

To investigate the possible relationship between altered expression (loss of membranous staining or nuclear accumulation) of beta-catenin and invasion/metastasis in early gastric cancer (EGC), beta-catenin was detected immunohistochemically in 116 cases of EGC, including 86 differentiated and 30 undifferentiated carcinomas. In parallel, immunohistochemical expression of c-erbB-2 was analyzed in all EGC cases. Regardless of histological type, altered expression of beta-catenin was found in 47% of mucosal carcinomas and 89% of carcinomas with submucosal invasion (p<0.001). Of particular interest is that beta-catenin alteration was found in almost all EGCs with lymph node metastasis, even though no significant statistical comparison could be made. These results suggest that molecular changes resulting in abnormal beta-catenin expression participate in the process of submucosal invasion and metastasis. While loss of expression was preferentially observed in undifferentiated EGCs, nuclear accumulation was found exclusively in 24% of differentiated EGCs. c-erbB-2 was overexpressed in only 16% of differentiated EGCs but there was no correlation between this overexpression and invasion or metastasis. However, it is intriguing that 12 out of 14 cases with c-erbB-2 overexpression also showed altered beta-catenin expression, suggesting that both molecules are involved in the development of a certain set of differentiated EGCs.

Adenocarcinoma↗
PubMed1999

Endoscopic stapling diverticulostomy for Zenker's diverticulum.

Endoscopic stapling diverticulostomy (ESD) using an endostapler is a modification of the standard endoscopic treatment of Zenker's diverticulum (ZD). It is characterized by complete myotomy of the upper esophageal sphincter, with division of the common wall between diverticulum and esophagus, followed by immediate simultaneous closure of the divided edges with the staples. ESD was performed on 21 patients with ZD between January 1996 and October 1997. The results were then evaluated. Operation time averaged 22 min. Wide opening of the diverticulum and excellent hemostasis were achieved. All of the patients but one, who died postoperatively of myocardial infarction, resumed oral intake without any evidence of cervical sepsis or mediastinitis. Complete relief of dysphagia was achieved in all 20 patients. Hospital stay averaged 4.7 days (range, 2-7 days). The patients were followed up after ESD for a median time period of 12 months. No relapses were recorded. ESD is an effective endoscopic treatment for ZD that entails a low risk of complications and requires only a short period of hospitalization.

Adult↗
PubMed1999

Self-guided robotic camera control for laparoscopic surgery compared with human camera control.

BACKGROUND: In laparoscopic surgery, the surgeon no longer has direct visual control of the operation area, and a camera assistant who maneuvers the laparoscope is essential. Problems of cooperation between the two naturally arise, and a robotic assistant that automatically controls the laparoscope can offer a highly desirable alternative to this situation. METHODS: A self-guided robotic camera control system (SGRCCS) based upon a color tracking method has been developed and its use evaluated in 20 cases of laparoscopic cholecystectomy and compared with using human camera control. RESULTS: In 83% of the patients the procedures were successfully completed with the SGRCCS. Set-up time for the robot averaged 21 minutes; and the surgical time with and without the robot averaged 54 and 60 minutes, respectively. Using the robot instead of a human camera assistant significantly reduced both the frequency of the camera correction, 2.2 per hour compared with 15.3 per hour, and frequency of the lens cleaning, 1.0 per hour compared with 6.8 per hour. Subjective assessment by the surgeon revealed that the robot performed better than the human assistant in 71 % of the cases. CONCLUSIONS: In laparoscopic surgery, the SGRCCS offered optimal camera guidance and helped to maintain the surgeon's concentration during the operation.

Cholecystectomy, Laparoscopic↗
PubMed1999

Pretherapeutic laparoscopic staging in advanced gastric carcinoma.

BACKGROUND AND STUDY AIMS: Direct visualization of the abdominal cavity by laparoscopy prior to multimodal treatment may be capable of improving the diagnostic precision of gastric cancer staging. The aim of this study was to evaluate whether diagnostic laparoscopy can influence treatment strategies in gastric cancer staged T3 and T4 by preoperative diagnostic tests. PATIENTS AND METHODS: Extended diagnostic laparoscopy (EDL) was carried out in 111 patients with advanced gastric cancer staged T3 or T4 by computed tomography (CT) and endoluminal ultrasound (EUS). On Lauren's classification of gastric cancer, 46% of the lesions were of the intestinal type and 54% of the nonintestinal type. EDL was carried out with the patients under general anesthesia, and included visual inspection of the abdomen, with surgical exploration of initially inaccessible regions, laparoscopic ultrasound examination, peritoneal lavage, and biopsies. The information provided by laparoscopy was classified as 1) no additional information, 2) important additional findings independent of the tumor stage, 3) downgrading of the tumor to a more favorable stage, and 4) upgrading of the tumor to a less favorable stage. The results of EDL were then compared with those obtained by sonography, CT and EUS in combination. RESULTS: EDL was performed successfully in 107 patients. In 56 of the 111 patients (50.5%), no additional findings were obtained. In 5.4% of cases, additional unforeseen information was found, not connected with the tumor but altering the management. EDL altered the preoperative diagnosis in 51 of the 111 patients (46.0%), leading to changes in management in 45 of them (40.5%). EUS provided additional information in eight cases (7.2% of the whole group, or 15.7% of those in whom the diagnosis had to be changed). Four metastases were detected using EDL. It was possible to rule out peritoneal spread in four patients, but it was newly detected in 26. CONCLUSIONS: Additional information by EDL about the tumor stage in gastric cancer led to a modification of the therapeutic strategy in 40% of patients, in spite of earlier comprehensive diagnostic work-up using modern imaging procedures. EDL should therefore be mandatory if neoadjuvant treatment is planned, in order to avoid either undertreatment or overtreatment of this type of tumor.

Adult↗
PubMed1999

Analgesic effect of intrathecal desipramine on carrageenan-induced thermal hyperalgesia in the rat.

We examined if intrathecal desipramine, a selective norepinephrine reuptake inhibitor, would modulate peripheral inflammation-induced hyperalgesia. Rats were chronically implanted with a lumbar intrathecal catheter and paw withdrawal latency (PWL) to noxious heat stimuli was assessed. Unilateral hindpaw inflammation was induced by intraplantar carrageenan injection. Carrageenan injection significantly (P < 0.05) reduced PWL of the injected paw (from mean 11.4 (SEM 0.6) s to 3.5 (0.2) s, 3 h after carrageenan), but not of the contralateral side (from 11.6 (0.2) s to 11.2 (0.5) s). Intrathecal desipramine 10, 30, 60 and 100 micrograms, which did not produce analgesic effects in untreated rats, dose-dependently reversed the shortened PWL on the ipsilateral side (3.3 (0.2), 5.3 (0.4), 6.2 (0.3) and 9.6 (0.2) s, respectively) without affecting the contralateral side. Pretreatment with intrathecal yohimbine 10 micrograms did not antagonize the anti-hyperalgesic effects of desipramine (from 9.6 (0.2) to 9.8 (0.3) s). Our results suggest that the mechanism underlying the analgesic effect of desipramine on inflammation-induced hyperalgesia is unlikely to be inhibition of norepinephrine reuptake within the spinal cord.

Adrenergic Uptake Inhibitors↗
PubMed1999

Activation of spinal N-methyl-D-aspartate receptors stimulates a nitric oxide/cyclic guanosine 3,5-monophosphate/glutamate release cascade in nociceptive signaling.

BACKGROUND: Increasing evidence has suggested the possibility that the activation of N-methyl-D-aspartate (NMDA) receptors modulates spinal nociceptive transmission via a nitric oxide (NO)/cyclic guanosine 3',5'-monophosphate (cGMP) pathway. However, the existence and the role of an NO/cGMP pathway in the modulation of spinal nociceptive transmission has been unclear. The authors hypothesized that the activation of NMDA receptors stimulates an NO/cGMP pathway, and this pathway evokes glutamate release within the spinal cord, modulating spinal nociceptive transmission. METHODS: The authors have examined the effects of an NO synthase inhibitor and a soluble guanylate cyclase inhibitor on the concentrations of NO metabolites (NO2-/NO3-) and glutamate in the cerebrospinal fluid after intrathecal perfusion of NMDA, concomitantly observing pain-related behavior (scratching, biting, and vocalization) in unanesthetized, free-moving rats using an intrathecal microdialysis method. The contents of cGMP in the dorsal horn were also measured using enzyme immunoassay method. RESULTS: Intrathecal perfusion of NMDA produced pain-related behavior and increased glutamate and NO2-/NO3-concentrations in a dose-dependent manner. A competitive NMDA receptor antagonist, D,L-2-amino-5-phosphonovaleric acid, completely blocked the NMDA-induced responses. An NO synthase inhibitor, N(G)-monomethyl-L-arginine acetate, at a dose that completely blocked the increase in NO2-/NO3-, inhibited both the NMDA-induced pain-related behavior and the increase in glutamate concentration. In addition, a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazole[4,3-a]quinoxaline-1-one, also inhibited significantly NMDA-induced pain-related behavior and the increase in glutamate concentration. NMDA induced an increase in cGMP in the dorsal half of the spinal cord, which was blocked by N(G)-monomethyl-L-arginine acetate. CONCLUSIONS: The results of this study support the hypothesis that the activation of NMDA receptors modulated pain-related behavior via an NO/cGMP/glutamate release cascade within the spinal cord.

2-Amino-5-phosphonovalerate↗