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Biomedical subjects

Y Okuda

Publications and source records attributed to Y Okuda.

At least 91 records · Page 5Linked to original sources

[Anesthetic management of an emergency surgery for panperitonitis during an asthmatic attack].

We report anesthetic management of an emergency surgery for panperitonitis during an asthmatic attack in a patient with angina pectoris. A 71-year-old male patient, complaining of abdominal pain and dyspnea, was diagnosed as having panperitonitis and asthmatic attack by surgeons in the emergency room. General anesthesia was induced by intravenous injection of propofol (30 mg), ketamine (30 mg), fentanyl (200 micrograms), suxamethonium (60 mg) and diltiazem (5 mg) following cannulation of the left radial artery for continuous monitoring of direct arterial pressure. Anesthesia was maintained by continuous infusion of propofol (4-10 mg.kg-1.h-1) and ketamine (1 mg.kg-1.h-1) in combination with intermittent epidural injection of local anesthetics. Although sudden onset of increased peak airway pressure occurred 45 minutes after starting operation, 50 mg of propofol injection and 500 mg of aminophyline infusion could relieve this high airway pressure. Because increased peak airway pressure appeared frequently and this could not be relieved by bolus injection of propofol, we changed the intravenous anesthesia to nitrous oxide-oxygen-isoflurane (GOI). After this change, no asthmatic attack occurred during the operation. While the mechanical ventilation was required during the early postoperative period along with infusion of aminophyline and inhalation of beta-stimulants, the patient was weaned successfully from the mechanical ventilation 12 hours postoperatively. It was speculated that the intraoperative asthmatic attack might have been caused by light level of anesthesia with propofol and ketamine. We concluded that other analgesics, such as fentanyl or epidural local anesthetics, must have been supplemented at proper timing during the continuous infusion of propofol and ketamine during the surgery.

Aged↗

[Usefulness of laryngeal mask for difficult intubation in a child with congenital laryngeal webs].

We report a case of difficult intubation with congenital laryngeal web. An 11-year-old boy was scheduled for urinary surgery. After anesthetic induction, the anesthesiologist encountered resistance at the vocal cord preventing satisfactory intubation. A size 3 laryngeal mask was immediately inserted, and an adequate airway was obtained. We found a laryngeal web at the vocal cord by bronchoscope inserted thorough the laryngeal mask. The peroperative course was uneventful. Immediately after removal of the laryngeal mask, the patient developed airway obstruction due to sputum and/or laryngeal spasm. The obstruction was relieved through application of positive pressure ventilation and aspiration of the sputum.

Airway Obstruction↗

[Two cases of extreme hemodilution caused by massive hemorrhage immediately after start of operation].

We describe two cases of extreme hemodilution due to large amounts of fluid infusion for unexpected massive hemorrhage. In both cases, unexpected hemorrhage with difficult hemostasis occurred within 60 min after the start of the operation. For lack of transfused blood, large amounts of fluid infusion using crystalloid and colloid solutions including 5% albumin, plasma expander and lactated Ringer's solution were administered to maintain circulatory blood volume. The hemoglobin concentration and hematocrit had been below 2.0 g.dl-1 and 10% for approximately one hour, respectively. The extreme hemodilution improved by the urgent blood transfusion. In one case, intraoperative autotransfusion with Cell-Saver was performed. In spite of intraoperative extreme hemodilution, their postoperative courses were uneventful. Intraoperative awareness was present in both cases.

Adult↗

[Use of intubating laryngeal mask airway for three patients with difficult intubation].

We used intubating laryngeal mask airway (ILM) for three patients with difficult intubation, and tracheal intubation was successfully performed through the ILM in all three cases. Difficult intubation in the first case was caused by direct invasion of malignant lymphoma into the right maxillary sinus leading to restricted mouth opening. Neck stiffness due to invasion of metastatic cancer into the cervical spine in the second case and facial trauma caused by traffic accident in the third case gave rise to the difficult intubation. Insertion of the ILM was successfully performed in all the patients following induction of general anesthesia, and the ventilation through the ILM was possible without any difficulties. Subsequently, all patients were intubated through the ILM successfully. We realized that the ILM is useful and should be prepared on the induction of anesthesia in patients suspected of difficult intubation.

Aged↗

[The effects of intravenous anesthetics, propofol, fentanyl and ketamine on the excitability of spinal motoneuron in human: an F-wave study].

We have investigated the effects of various intravenous anesthetics, propofol, fentanyl and ketamine on the excitability of spinal motoneuron using an F-wave analysis in a total of 28 patients. All patients were divided randomly into three groups as follows; 2 mg.kg-1 intravenous bolus injection followed by 6 mg.kg-1.h-1 infusion of propofol (P group), 1 mg.kg-1 intravenous bolus injection followed by 1 mg.kg-1.h-1 infusion of ketamine (K group), and 5 micrograms.kg-1 injection of fentanyl (F group). The F-wave was determined after supramaximal electrostimulation of the median nerve in distal point. After establishing stable baseline values, intravenous injection of one of the three anesthetics was applied. The F-wave was recorded 3 minutes after the time of bolus administration. We found a significant (P = 0.018) reduction of the persistence from 77.5 +/- 15.2 to 40.9 +/- 16.8% in the propofol group. On the other hand, no significant changes in F-wave parameters were found in ketamine, or fentanyl group. These results suggested that motoneuron excitability in spinal cord could be inhibited by anesthetic dose of propofol, but not by ketamine or fentanyl.

Adult↗

[Target-controlled propofol infusion for general anesthesia in three obese patients].

We report three cases in which the target-controlled propofol infusion technique was used in obese patients for general anesthesia. General anesthesia was induced by intravenous administration of fentanyl 150-300 micrograms and ketamine 50-80 mg and propofol 2 micrograms.ml-1 to achieve a target blood concentration by target-controlled infusion system. Anesthetic maintenance was achieved by ketamine 1 mg.kg-1.h-1 for 1 hour after the induction, propofol at target blood concentration of 2-3.5 micrograms.ml-1 and the intermittent epidural injection of 1.5% lidocaine through an epidural catheter. The surgical procedures were uneventful. The estimated blood concentrations of propofol at emergence from anesthesia calculated by ConGrace ranged from 1.49-1.69 micrograms.ml-1, and it took 230-300 seconds to emerge from anesthesia. The target-controlled propofol infusion technique appears useful to control the depth of anesthesia in obese patients.

Adult↗

[Damage of a laryngeal mask airway during anesthesia].

A 21-year-old man was scheduled for fixation of a fractured radius and ulna under general anesthesia using a laryngeal mask airway (LM). Anesthesia was induced with propofol 120 mg and fentanyl 0.1 mg. After administration of vecuronium 6 mg, we attempted insertion of the LM (# 5). The first trial was unsuccessful because the tube of the LM was bent in the pharynx. We attempted it again and the LM was successfully inserted. It was connected with the anesthetic circuit, and manual ventilation was started. However, the LM was suddenly broken at the basal part of the tube connector before the start of operation, and it became detached from the anesthetic circuit. Therefore, we removed the remaining LM from the mouth, and inserted a new LM (# 5). The peroperative course was uneventful. We conclude that inspection of a recycled LM is important before using it in order to prevent such an event as the present case.

Adult↗

[A case of acute urticaria from hydroxyzine hydrochloride used for preanesthetic medication].

We report a case of acute urticaria probably caused by hydroxyzine hydrochloride. A 66-year-old male was scheduled for cardiac cystectomy by thoracic endoscopy. The patient was premedicated with atropine and hydroxyzine intramuscularly 30 min before arrival in the operating room. Abrupt general exanthema was observed when intravenous infusion was started. Although his general condition was stable, the operation was postponed. Three days later, the skin test was performed using several drugs. Only hydroxyzine hydrochloride gave positive result. It is assumed that hydroxyzine hydrochloride may have caused his urticaria.

Acute Disease↗

[Comparison between total intravenous anesthesia and inhalation anesthesia in the surgery of acute cholecystitis].

We investigated retrospectively the influence of anesthetic methods on the intraoperative managements and postoperative outcomes in 26 patients receiving emergency or early surgery for acute cholecystitis. Fourteen of the 26 patients received total intravenous anesthesia with propofol, fentanyl, and ketamine (PFK group), while the remainder received nitrous oxide and isoflurane or sevoflurane anesthesia (GO group). There were no significant differences between the groups with respect to demographic data. We found no significant differences between the groups in duration of operation and anesthesia, the incidence of intraoperative hypotension, and the use of ephedrine and dopamine during induction and maintenance of anesthesia. After surgery, the PFK group had significantly earlier bowel function than the GO group, with earlier starting of oral intake (54.0 +/- 25.1 vs 89.3 +/- 31.9 hours after surgery; P = 0.026). These data suggest that total intravenous anesthesia by propofol, fentanyl, and ketamine may provide the earlier recovery of bowel function than inhaled anesthesia after emergency or early surgery for acute cholecystitis.

Acute Disease↗

Induction of cyclooxygenase-2 in rat gastric mucosa by rebamipide, a mucoprotective agent.

Recent studies indicate an expression of mitogen-inducible cyclooxygenase (COX-2) in gastric mucosa. Rebamipide, a mucoprotective agent enhances prostaglandin (PG) synthesis. The present study was designed to clarify the mechanism for rebamipide-induced mucosal protection. Male Sprague-Dawley rats were administered 5, 15, or 50 mg/kg/day rebamipide for 14 days. The expression of constitutive cyclooxygenase (COX-1) and COX-2 in gastric mucosa was determined using Western blot analysis. Another series of rats was used to examine 1) the levels of PGE(2) in stomach with and without pretreatment with a COX-2 inhibitor; 2) the protective action of rebamipide against gastric damage caused by 0.6 N HCl; and 3) the effects of a COX-2 inhibitor on rebamipide-induced gastric mucosal protection. COX-2 expression was enhanced, whereas COX-1 expression did not change significantly in the gastric mucosa of rats after treatment with rebamipide. The gastric mucosal PGE(2) was higher in the rebamipide groups than in the vehicle-treated group. Rebamipide also suppressed gastric damage induced by HCl in a dose-dependent manner. A COX-2 inhibitor blocked the rebamipide-induced increase in mucosal PGE(2), and mucosal protection induced by rebamipide. The results indicate that rebamipide induces COX-2 expression, increases PGE(2) levels, and enhances gastric mucosal defense in a COX-2-dependent manner. Thus, COX-2 has an important role in the effects of rebamipide on gastric mucosal protection.

Alanine↗

[Pre-emptive analgesia with intravenous ketamine reduces postoperative pain in young patients after appendicectomy: a randomized control study].

Thirty-six young patients (12-17 years old) for appendicectomy were randomly allocated to receive ketamine 0.5 mg.kg-1 (K 0.5 group; n = 12), ketamine 1.0 mg.kg-1 (K 1.0 group; n = 12), or lactated Ringer's solution 5 ml (control group; n = 12), which was administered intravenously before incision. After the surgery, all patients received a nonsteroidal anti-inflammatory drug (NSAID) without limitation as requested by the patient. Pain scores at rest and on movement were assessed at 6-10 hr, 24 hr, and 48 hr post-operatively using a visual analogue scale. The frequency at which NSAID was given for postoperative analgesia in the first 48 hr after the surgery was recorded. The patients in the K 0.5 and K 1.0 groups had significantly lower pain scores at rest 6-10 hr postoperatively than the patients in the control group (P < 0.05). Additionally, the patients in the K 1.0 group had a significantly lower pain score on movement 6-10 and 48 hr postoperatively than those in the control group (P < 0.05). The K 0.5 and K 1.0 groups each used significantly less NSAID during the 48-hr postoperative period than the control group (P < 0.05). Intravenous administration of ketamine before incision was associated with decreases in pain at rest 6-10 hr postoperatively and a reduction in NSAID requirement after appendicectomy. Administration of ketamine 1.0 mg.kg-1 prior to incision was superior to administration of 0.5 mg.kg-1 in relief of pain on movement after the surgical procedure.

Adolescent↗

The conserved tryptophan-arginine-tyrosine motif of a proteinaceous alpha-amylase inhibitor T-76 from Streptomyces nitrosporeus is important for inhibition of animal alpha-amylases but not for an alpha-amylase from Bacillus sp. no. 195.

Site-directed mutagenesis of Trp-16, Arg-17, and Tyr-18, which were thought to form a putative active site in proteinaceous alpha-amylase inhibitor T-76 from Streptomyces nitrosporeus for inhibition, was performed. The mutation at the site (W16A, R17A, and Y18A) resulted in a marked decrease in inhibitory activity against all animal alpha-amylases tested. Only the alpha-amylase from Bacillus sp. no. 195 (BAA) remained sensitive to all the constructed mutant inhibitors. A competition between T-76 mutants and the wild-type for porcine pancreatic alpha-amylase (PPA) suggest that the loss of inhibitory activity against PPA in mutant inhibitors was due to the decrease in their binding ability for PPA. T-76 formed a complex with BAA as well as PPA at the stoichiometric ratio of 1:1. A competition between BAA and the PPA/T-76 complex suggests that PPA and BAA might bind to the same region or regions close to each other on the T-76 molecule. These results indicate that the conserved Trp-Arg-Tyr motif of T-76 is involved in the interaction between T-76 and PPA while other amino acid residues seem to be important for the T-76/BAA interaction. Since the BAA-type alpha-amylase is the actual target of the inhibitors from microbes in comparison with animal alpha-amylases, BAA might be a better material than PPA to elucidate the "true" function of proteinaceous alpha-amylase inhibitors.

Journal Article↗

IL-6 plays a crucial role in the induction phase of myelin oligodendrocyte glucoprotein 35-55 induced experimental autoimmune encephalomyelitis.

We investigated the role of IL-6 in myelin oligodendrocyte glycoprotein (MOG) peptide induced experimental autoimmune encephalomyelitis (EAE) using IL-6-deficient mice and found that IL-6-deficient mice were resistant to active induction of EAE, but that the treatment of those mice with IL-6 during the preclinical phase caused typical EAE. We also found that both wild-type and IL-6-deficient mice were resistant to passive transfer of EAE by lymphocytes from IL-6-deficient mice, but that passive transfer of lymphocytes from wild-type mice induced typical EAE in IL-6-deficient mice. Histological abnormalities of the central nervous system (CNS) in those IL-6-deficient mice with EAE were similar to those in wild-type mice with EAE. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed no difference in the production of inflammatory cytokines such as IL-1beta, IL-2, TNF-alpha, and IFN-gamma in the CNS of IL-6-deficient mice with EAE as compared to the CNS of wild-type mice with EAE. These results indicated that IL-6 might be an important factor in the induction phase, but might have little influence on the effector phase of EAE. We further estimated the production of cytokines in MOG-stimulated lymph node (LN) cells by enzyme-linked immunosorbent assay. Increased IL-4 and IL-10 production and reduced IL-2 and IFN-gamma production were observed in LN cells from IL-6-deficient mice as compared to LN cells from wild-type mice. These results suggested that a shift of T cell responses from Thl to Th2 might explain the resistance of IL-6-deficient mice to EAE. Taken together, IL-6 may play a crucial role in the induction phase of EAE by modulating Th1/Th2 balance.

Animals↗

Eicosapentaenoic acid inhibits vasopressin-activated Ca2+ influx and cell proliferation in rat aortic smooth muscle cell lines.

The purpose of this study was to clarify how eicosapentaenoic acid (EPA), an omega-3 polyunsaturated fatty acid, modulates the vascular action of vasopressin in rat aortic smooth muscle cell lines. The effects of EPA on Ca2+ mobilization and DNA synthesis elicited by vasopressin were investigated and compared to those of Ca2+ channel blocking agents, by means of Ca2+ measurements and the incorporation of [3H]thymidine. Patch-clamp techniques were also employed. Vasopressin (100 nM) elicited an initial peak of intracellular Ca2+ ([Ca2+]i), followed by a sustained phase due to Ca2+ entry. Nifedipine or nicardipine (1 microM), a potent L-type Ca2+ channel blocker, partly inhibited the sustained phase, but La3+ completely abolished it. EPA (10 microM) also inhibited it even in the presence of nicardipine. Under voltage-clamp conditions with CsCl-internal solution, depolarizing pulses positive to -30 mV from a holding potential of -40 mV elicited a slow inward current. The inward current was blocked by La3+, nicardipine, and nifedipine (1 microM), suggesting that the inward current mainly consisted of the voltage-dependent L-type Ca2+ channel (ICa.L). EPA (1-30 microM) also inhibited ICa.L in a concentration-dependent manner. The inhibitory effect of EPA was observed at concentrations higher than 1 microM, and its half-maximal inhibitory concentration (IC50) was 7.6 microM. Vasopressin induced a long-lasting inward current at a holding potential of -40 mV. The vasopressin-induced current was considered as a non-selective cation current (Icat) with a reversal potential of approximately +0 mV. Both nifedipine and nicardipine (10 microM) failed to inhibit it significantly, but La3+ completely abolished Icat. EPA also inhibited vasopressin-induced Icat in a concentration-dependent manner; its IC50 value was 5.9 microM. Vasopressin (100 nM) stimulated [3H]thymidine incorporation. Exclusion of extracellular Ca2+ with EGTA or La3+ markedly inhibited it. EPA (3-30 microM) also inhibited the incorporation induced by vasopressin, while nifedipine and nicardipine (1 microM) only partly inhibited it. These results suggested that EPA, unlike nifedipine and nicardipine, inhibited vasopressin-induced Ca2+-entry and proliferation in rat vascular smooth muscle cells, where the inhibitory effects of EPA on Icat as well as ICa.L might be involved. Thus, EPA would exert hypotensive and antiatherosclerotic effects.

Animals↗

Troglitazone inhibits voltage-dependent calcium currents in guinea pig cardiac myocytes.

BACKGROUND: It has been suggested that intracellular Ca2+ overload in cardiac myocytes leads to the development of diabetic cardiomyopathy. Troglitazone, an insulin-sensitizing agent, is a promising therapeutic agent for diabetes and has been shown to prevent diabetes-induced myocardial changes. To elucidate the underlying mechanism of troglitazone action on cardiac myocytes, the effects of troglitazone on voltage-dependent Ca2+ currents were examined and compared with classic Ca2+ antagonists (verapamil and nifedipine). METHODS AND RESULTS: Whole-cell voltage-clamp techniques were applied in single guinea pig atrial myocytes. Under control conditions with CsCl internal solution, the voltage-dependent Ca2+ currents consisted of both T-type (ICa,T) and L-type (ICa,L) Ca2+ currents. Troglitazone effectively reduced the amplitude of ICa,L in a concentration-dependent manner. Troglitazone also suppressed ICa,T, but the effect of troglitazone on ICa,T was less potent than that on ICa,L. The current-voltage relationships for ICa,L and the reversal potential for ICa,L were not altered by troglitazone. The half-maximal inhibitory concentration of troglitazone on ICa,L measured at a holding potential of -40 mV was 6.3 micromol/L, and 30 micromol/L troglitazone almost completely inhibited ICa,L. Troglitazone 10 micromol/L did not affect the time courses for inactivation of ICa,L and inhibited ICa,L mainly in a use-independent fashion, without shifting the voltage-dependency of inactivation. This effect was different from those of verapamil and nifedipine. Troglitazone also reduced isoproterenol- or cAMP-enhanced ICa,L. CONCLUSIONS: These results demonstrate that troglitazone inhibits voltage-dependent Ca2+ currents (T-type and L-type) and then antagonizes the effects of isoproterenol in cardiac myocytes, thus possibly playing a role in preventing diabetes-induced intracellular Ca2+ overload and subsequent myocardial changes.

Animals↗

Inhibitory effect of Epstein-Barr virus activation by Citrus fruits, a cancer chemopreventor.

To search useful compounds in Citrus fruit for cancer chemoprevention, we carried out a primary screening of extracts of fruit peels and seeds from 78 species of the genus Citrus and those from two Fortunella and one Poncirus species, which were closely related to the genus Citrus. These Citrus extracts inhibited the Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) as a useful screening method for anti-tumor promoters. Our results indicated that Citrus containing substances may be inhibit susceptibility factors involved in the events leading to the development of cancer.

Animals↗

Anti-tumor-promoting effects of 8-substituted 7-methoxycoumarins on Epstein-Barr virus activation assay.

In a search for anti-tumor-promoting agents, we carried out a primary screening of twenty-nine 8-substituted and four 6-substituted derivatives of 7-methoxycoumarins isolated from plants of the Murraya and/or Citrus species (Rutaceae), examining their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. This investigation indicated that the prenyl (3-methyl-2-butenyl) or 2-hydroxy-3-methylbutyl (or butenyl) unit as an isoprenoid moiety at C-8 on the 7-methoxycoumarin nucleus plays an important role in the anti-tumor-promoting activity. Some of the 8-substituted 7-methoxycoumarins isolated from Murraya species, murrangatin (7), minumicrolin (10) and chloticol (18), were found to significantly inhibit EBV-EA activation, and preserved the high viability of Raji cells, suggesting that 7, 10 and 18 might be valuable anti-tumor-promoting agents.

Antineoplastic Agents↗

Effects of omental wrap on performance of small-caliber high-porosity expanded polytetrafluoroethylene grafts.

The purpose of this study was to evaluate the effects of omental wrap on the performance of small-caliber expanded polytetrafluoroethylene (ePTFE) grafts, with a special reference to transmural capillary ingrowth. High-porosity ePTFE grafts with a fibril length of 60 micrometer, an internal diameter of 4 mm, and 40 mm in length were implanted into the canine bilateral carotid arteries. The grafts on the right side were wrapped in an omental pedicle flap (omentum-wrap grafts), while those on the left were not (nonwrap grafts). The grafts were retrieved at intervals of 4 and 12 weeks. At 4 weeks, the patency rates of the omentum-wrap grafts and nonwrap grafts were almost the same (5/6 vs 6/6). At 12 weeks, patency tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (3/5 vs 1/5). At 4 weeks, the thrombus-free surface score (TFS) was significantly higher in the omentum-wrap grafts than in the nonwrap grafts (44.8% vs 30.2%, P < 0.05). At 12 weeks, the TFS tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (84.6% vs 62.4%). At 4 weeks, both the capillary transsectional area score (CTS) and capillary density were significantly higher in the omentum-wrap grafts than in the nonwrap grafts (CTS, 3.3% vs 1.1%, P < 0.05; capillary density, 196.0/mm2 vs 83.3/mm2, P < 0.05). At 12 weeks, both CTS and capillary density tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (CTS, 1.1% vs 0%; capillary density, 69.4/mm2 vs 0/mm2). At 4 weeks, in the omentum-wrap grafts, extracellular matrices and cells in the interstices of the graft were stained with an antibody against VEGF. In conclusion, the omental wrap enhances transmural capillary ingrowth and thereby promotes endothelialization in small-caliber high-porosity ePTFE grafts. VEGF appears to play an active role in transmural capillary ingrowth enhanced by omental wrap.

Anastomosis, Surgical↗