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Biomedical subjects

Masahiko Ozaki

Publications and source records attributed to Masahiko Ozaki.

7 recordsLinked to original sources
PubMed2006

Off-pump coronary artery bypass grafting for a patient with anomalous origin of the right coronary artery from the pulmonary artery.

We report on a case of a 70-year-old chronic hemodialysis patient. He presented with anomalous origin of the right coronary artery from the pulmonary artery (ARCAPA) and severe left anterior descending coronary artery (LAD) stenosis, which supplied collateral flow to the right coronary artery (RCA). The patient complained of myocardial ischemic symptoms during routine hemodialysis. We performed off-pump coronary artery bypass grafting (OPCABG) surgery and ligation of the origin of the ARCAPA. Previous reports described that the myocardial ischemia was a rare complication with the ARCAPA patients. However, this case required coronary revascularization because of the atherosclerotic LAD stenosis as a collateral source of the RCA.

Aged↗
PubMed2005

Effect of a selective GABA(B) receptor agonist baclofen on the mu-opioid receptor agonist-induced antinociceptive, emetic and rewarding effects.

The management of excessive adverse effects of opioids is a major clinical problem. The present study was undertaken to investigate the effect of a selective gamma-aminobutyric acid (GABA)(B) receptor agonist baclofen on the mu-opioid receptor agonist-induced antinociceptive, emetic and rewarding effects. Either morphine or fentanyl produced a dose-dependent antinociceptive effect in both ferrets using Randall-Selitto test and mice using tail-flick test. Under these conditions, pretreatment of baclofen produced an additive antinociception induced by morphine or fentanyl. Furthermore, the augmentation of antinociception induced by systemic administration of baclofen with morphine or fentanyl was completely abolished by either i.c.v. or i.t. pretreatment with the selective GABA(B) receptor antagonist CGP 35348 in mice. We next investigated the emetic response induced by mu-opioid receptor agonist in ferrets. Morphine at lower doses than that used for antinociceptive assay produced both retching and vomiting, whereas fentanyl failed to produce the retching and vomiting in ferrets. Here we reported for the first time that baclofen significantly suppressed the retching and vomiting induced by morphine, indicating the involvement of GABA(B) receptor in emetic control pathway. Furthermore, baclofen also inhibited place preference elicited morphine or fentanyl in rats. Taken together, these results suggest that co-administration of baclofen with mu-opioid receptor agonist produced a potentiation of antinociceptive effect, whereas an untoward effect was completely blocked.

Analgesics, Opioid↗
PubMed2005

[Basic studies on cancer pain control].

According to the World Health Organization (WHO) guidelines for patients with moderate or severe pain, morphine has been used as a "gold standard" treatment for cancer pain. Recent clinical experiences have demonstrated that when morphine is used to control pain in cancer patients, psychological dependence is not a major concern. However, undue anxiety about psychological dependence on morphine in cancer patients has caused physicians and patients to use inadequate doses of opioids. In basic research, we reported that the morphine-induced rewarding effects can be dramatically suppressed under a neuropathic pain-like state induced by sciatic nerve ligation and an inflammatory pain-like state produced by intraplantar injection of formalin or carrageenan in rodents. The use of morphine for the treatment of pain is sometimes accompanied with side effects such as emesis, constipation and drowsiness. We show that the lower doses of morphine produce emesis, whereas antinociceptive doses of morphine show no emetic responses in ferrets. These findings provide further evidence that an adequate dose of morphine is useful and safe in a clinical setting.

Analgesics, Opioid↗
PubMed2004

Role of extracellular signal-regulated kinase in the ventral tegmental area in the suppression of the morphine-induced rewarding effect in mice with sciatic nerve ligation.

We recently reported that micro-opioid receptor agonist morphine failed to induce its rewarding effects in rodents with sciatic nerve injury. In the present study, we investigated whether a state of neuropathic pain induced by sciatic nerve ligation could change the activities of the extracellular signal-regulated kinase (ERK) and p38 in the mouse lower midbrain area including the ventral tegmental area (VTA), and these changes could directly affect the development of the morphine-induced rewarding effect in mice. The sciatic nerve ligation caused a long-lasting and profound thermal hyperalgesia. A dose-dependent place preference induced by s.c. administration of morphine was observed in sham-operated mice, but not in sciatic nerve-ligated mice. We found here for the first time that nerve injury produces a sustained and significant reduction in protein levels of phosphorylated-ERK and -p38 in cytosolic preparations of the mouse lower midbrain. The inhibition of ERK activity by i.c.v. pre-treatment with either PD98059 or U0126 impaired the morphine-induced place preference. In contrast, i.c.v. treatment with a specific inhibitor of p38, SB203580, did not interfere with the morphine-induced rewarding effect. Immunohistochemical study showed a drastic reduction in phosphorylated-ERK immunoreactivity within tyrosine hydroxylase-positive cells of the VTA. These results suggest that a sustained reduction in the ERK-dependent signalling pathway in dopamine cells of the VTA may be implicated in the suppression of the morphine-induced rewarding effect under neuropathic pain.

Analgesics, Opioid↗
PubMed2004

[Infective endocarditis caused by methicillin resistant Staphylococcus aureus following corticosteroid pulse therapy; report of a case].

A 51-year-old man, with a history of corticosteroid pulse therapy 3 weeks previously, developed infective endocarditis of the mitral valve due to methicillin resistant Staphylococcus aureus, and underwent mitral valve replacement. Since the second postoperative day, clinical course was seriously complicated because of recurrent abdominal pain corresponding with commencement of oral intake, unremitting spike fever, and renal and hepatic dysfunction. Various examinations except angiography failed to demonstrate the etiology. Two months later, the patient developed panperitonitis due to perforation of ischemic ulcer of the cecum and underwent ileo-cecal resection. After this operation, he convalesced very quickly. Ischemia is one of the main causes of abdominal complication following cardiac surgery. Angiography should be positively considered in cases like the present one.

Abdominal Pain↗
PubMed2003

Effectiveness of Roux-en-Y reconstruction after distal gastrectomy based on an assessment of biliary kinetics.

PURPOSE: To evaluate the efficiency of Roux-en-Y reconstruction (RY) after distal gastrectomy we compared postoperative physiological functions and disorders among patients who underwent RY, conventional Billroth I reconstruction (BI), or Billroth II reconstruction (BII). METHODS: The subjects were 91 patients who had undergone distal gastrectomy for gastric cancer more than 1 month earlier. To examine the severity of gastroesophageal reflux, acid reflux and alkali reflux were assessed, and to examine the severity of duodenal reflux into the remnant stomach, biliary scintigraphy was performed. The degree of inflammation in the esophagus and remnant stomach was examined by endoscopy. Questionnaires on postoperative complaints were sent out to the patients to determine how serious their reflux symptoms were. RESULTS: Both acid and alkali reflux were mild in the RY group. Biliary reflux into the remnant stomach, as assessed by biliary scintigraphy, was significantly less severe in the RY group than in the BI and BII groups. Endoscopy showed that inflammation of the lower esophagus and remnant stomach was much less severe in the RY group than in the BI and BII groups. According to the questionnaire survey, none of the patients in the RY group reported any reflux symptoms. CONCLUSIONS: In this series, RY was found to be a superior reconstruction method after distal gastrectomy since it was rarely accompanied by the reflux of duodenal juice into the remnant stomach or gastric reflux into the lower esophagus.

Anastomosis, Roux-en-Y↗