Yasuhiro Maehara

Hiroshima University, Hirosima, Hiroshima, Japan

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Publications (11)4.61 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Osteopathic changes sometimes occur in patients with complex regional pain syndrome (reflex sympathetic dystrophy and causalgia). We aimed to investigate whether such osteopathic changes occurred in rats with chronic constriction injury (CCI) of the sciatic nerve. A CCI of the sciatic nerve was established in a unilateral hind limb in 39 adult Sprague-Dawley rats, which were killed 1, 2, 3, 5, or 7 weeks after the CCI procedure. Bone mineral content (BMC) and bone mineral density (BMD) in extracted tibial bones were measured using a dual-energy X-ray absorptiometer, and the number of osteoclasts in the metaphyseal regions was counted by the use of tartrate-resistant acid phosphate (TRAP) staining. BMC was significantly decreased, compared with that of the contralateral side, 1 to 7 weeks after CCI, and BMD was decreased 2 to 7 weeks after the procedure in the ipsilateral tibial bones, compared with BMD in the contralateral bones. The number of TRAP-positive multinucleated osteoclasts in the ipsilateral bones was significantly increased at 2, 3, and 5 weeks after the CCI, when compared with the number of these osteoclasts in the contralateral bones. The results of the present study demonstrate that osteopathic changes are associated with chronic constrictive injury of the sciatic nerve.
    No preview · Article · Feb 2002 · Journal of Bone and Mineral Metabolism
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    ABSTRACT: The addition of vasoconstrictors for spinal anesthesia is controversial, since an increase in the incidence of transient neurologic symptoms (TNS) has been reported. A multicenter, randomized, double-blind study was conducted to assess the effectiveness of spinal anesthesia with phenylephrine in addition to tetracaine as well as the incidence of neurological complications. We studied 64 patients with comparable demographic characteristics who were scheduled for elective surgery for a lower limb, or a gynecological or urological procedure. The patients were allocated randomly into 2 groups. Group P (n = 34) received 0.5% tetracaine in 10% glucose with 0.025% phenylephrine, while group C (n = 30) received 0.5% tetracaine in 10% glucose. Our results showed that only 2 patients (6.7%) in group C experienced TNS, and their symptoms disappeared within 72 hr after anesthesia, while none of the patients (0%) in group P complained of symptoms. The incidence of TNS was thus not significantly different between the two groups. Six hours after the sensory block, group P patients demonstrated sensory disturbance, with the median spinal dermatome corresponding to the L1 segment. Moreover, systolic blood pressure in group P was significantly higher than that in group C, 5 min, 15 min, and 20 min after injection. The incidence of TNS in the present study does not seem to be greater after surgery with spinal anesthesia using 0.5% hyperbaric tetracaine and 0.5 mg phenylephrine than without phenylephrine. Randomized, double-blind, cross-over trials with a larger sample size would be required in the future to obtain more reliable results.
    No preview · Article · Jul 2001 · Hiroshima journal of medical sciences
  • M Kawamoto · K Mukaida · Y Maehara · O Yuge
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    ABSTRACT: An abnormally accelerated Ca-induced Ca release (CICR) rate is known to be correlated with malignant hyperthermia susceptibility (MHS). To analyze significant clinical findings concerning CICR rate and develop a computer program for its prediction in human MHS. Using data from 146 subjects who had received a muscle biopsy for the determination of CICR rate, because of their anesthesia-related MHS history, we analyzed 23 different clinical features. There were 71 subjects with an abnormally accelerated CICR rate and 75 with a normal rate. Accelerated CICR rate was used as the objective variable whilst clinical findings and ages were used as independent variables and control variables, respectively. A multiple logistic regression model was employed for the analyses and the most suitable formulae for prediction were determined for use in the development of a computer program. The following 8 clinical findings were determined to be the most significant: the presence of muscle rigidity, the most serious PaCO2 reading (mmHg), peak body temperature (degree C), body temperature rate of increase over 15 minutes (degree C/15 minutes), most serious arterial pH reading, administration of dantrolene, improvement of acidosis with dantrolene, and time elapsed to peak body temperature after administration of anesthetics (minutes). By ranking the subject ages into 14 groups, we were able to minimize the prediction error rate with each corresponding formula. The computer program developed for prediction whilst consisted of these formulae yielded a sensitivity of 80% and a specificity of 86%. This method of prediction may contribute to the accurate prediction of CICR rate at the bedside. For clinical convenience, we will distribute the computer program upon request.
    No preview · Article · Jan 2001 · In vivo (Athens, Greece)
  • K. Oshita · K. Moriwaki · H. Fukuda · Y. Maehara · M. Kawamoto · O. Yuge
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    ABSTRACT: Ten patients with typical cluster headache, nine males and one female, ranging in age from 24 to 53 years old, were retrospectively studied on the efficacy of treatments. Stellate ganglion block, ergotamine, ketotifen, flunarizine, dimetotiazine P.O. or prostaglandin E1 derivatives I.V. was applied as prophylactic measures. Stellate ganglion block, supraorbital nerve block, oxygen inhalation, oral administration of ergotamine and NSAIDs were used as abortive treatments when patients were in the attack. Stellate ganglion block was effective to alleviate the degree of the oncoming attack and prolonged the intervals between attacks in all the patients, but oral and intravenous medications were less effective. Ergotamine and oxygen inhalation were two of the most effective abortive treatments for the mild to moderate attack. Their effective rates were 88.9% and 100%, respectively. However, the pain was refractory to all of the treatments when it was severe. Development of more effective prophylactic and strong abortive treatments are mandatory for adequate treatments of cluster headache.
    No preview · Article · Jan 2001 · Anesthesia and Resuscitation
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    ABSTRACT: One hundred and twenty-three patients with early or advanced cancer who had been referred to our pain clinic were studied retrospectively to investigate current problems with pain management for cancer patients. Pain due to advanced cancer and prolonged post-thoracotomy pain were two major reasons for referral. It was found that 51.7% of the patients with advanced cancer had not been treated appropriately with the WHO protocol for cancer pain relief before referral; however, increased administration of morphine did not necessarily relieve cancer pain, and in fact decreased the QOL of some patients; and 47.7% of patients with cancer pain were effectively treated with nerve block therapy. The present investigation also indicates that many patients who had undergone thoracotomy suffered prolonged post thoracotomy pain. Although post-thoracotomy pain was refractory to NSAIDs, trigger point injections with or without intercostal nerve block were effective in 65.4% of such patients. We conclude that further propagation of the WHO protocol for cancer pain relief, appropriate use of nerve block and establishment of practical guidelines for multidisciplinary management of pain are mandatory for improving the QOL of patients with cancer.
    No preview · Article · Jul 2000 · Masui. The Japanese journal of anesthesiology
  • H Tanaka · K Moriwaki · Y Maehara · M Kawamoto · O Yuge
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    ABSTRACT: We evaluated risk of bradycardia after endoscopic electrocautery of the upper thoracic sympathetic ganglia (ETS). Enrolled in this study were 24 patients. Bradycardia, defined as heart rate below 50 beats per min continuing for more than 5 min, was found in 12 patients (50%). All patients were divided into two groups; bradycardia group and non-bradycardia group. Age, sex, region of electrocautery, fentanyl dosage, and operation time were not different between the two groups. Power spectral analysis of heart rate variability revealed that sympathetic activity decreased after ETS. Multivariate analysis indicates that postoperative-minimal heart rate depends upon preoperative heart rate at rest. We conclude that careful monitoring after ETS is necessary in a patient with heart rate below 60 bpm preoperatively.
    No preview · Article · Jul 2000 · Masui. The Japanese journal of anesthesiology
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    ABSTRACT: We compared the results of the in vitro caffeine-halothane contracture test (CHCT) according to the protocols of the North American Malignant Hyperthermia Group (NAMHG) and the European Malignant Hyperthermia Group (EMHG) with the Ca-induced Ca release (CICR) rate test in the same patients with suspected malignant hyperthermia (MH). Five normal controls and 16 patients suspected of having MH susceptibility were studied. Muscle biopsies were usually obtained from the musculus vastus lateralis. Diagnostic cutoff points and procedures for CHCT protocols were as described in the original and renewal versions of NAMHG and EMHGs. The CICR rate test was performed according to the protocol reported by Endo et al. All five normal controls and two patients with abortive MH, two with postoperative hyperthermia, and three with high serum creatine kinase levels were normal in the three tests. Three patients with MH reactions and one patient with a history of masseter spasm were classified as MH positive according to NAMHG criteria and MH susceptible and MH equivocal according to EMHG criteria. There were five cases with discordant results between the CHCT and CICR rate tests. We propose that muscle biopsy for diagnosis of MH susceptibility should combine the CHCT with the CICR rate test, which may identify the defective site of Ca release channels.
    No preview · Article · Feb 2000 · Journal of Anesthesia
  • Yasuhiro Maehara · Keiko Mukaida · Masashi Kawamoto · Osafumi Yuge

  • Y Maehara · K Mukaida · E Hiyama · M Morio · M Kawamoto · O Yuge
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    ABSTRACT: Some genetic studies have shown a linkage between malignant hyperthermia susceptibility (MHS) and chromosome 19q or the skeletal muscle ryanodine receptor (RYR1) gene. Some types of MHS seem to be caused by an abnormality of calcium-induced calcium release (CICR). We analyzed the linkage of RYR1 gene polymorphisms in Japanese MHS families and investigated the correlation between genetic evidence of RYR1 gene mutations and an accelerated rate of CICR. We studied 63 subjects who were referred to our institute for investigation of MHS. CICR rates were measured by the skinned fiber method in 23 subjects. DNA samples were collected from 63 individuals belonging to 22 unrelated families. Restriction fragment length polymorphism (RFLP) analyses on the RYR1 locus and hypervariable microsatellite analysis were performed. We found one family with a linkage between acceleration of the CICR mechanism and a group of RFLPs. In CICR tests, ten of the 11 patients who had presented with fulminant MH showed accelerated rates of CICR. Analysis for the mutation C1840T, which was performed in 63 samples, did not demonstrate an alteration in any of the patients. Although we found heterozygotes in RFLP studies, we did not recognize a specific relationship between the acceleration of CICR and the RFLPs. We suggest a linkage between the acceleration of CICR and an abnormal human RYR1 gene in MHS. These results also suggest that heterogeneity exists for MH. We conclude that genetic tests cannot replace CICR tests or caffeine-halothane contracture tests with muscle biopsy as a diagnosing test for MH in the near future.
    No preview · Article · Apr 1999 · Hiroshima journal of medical sciences