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Biomedical subjects

Makoto Ozaki

Publications and source records attributed to Makoto Ozaki.

At least 19 recordsLinked to original sources
PubMed2006

Effects of dopamine and olprinone on ventricular energetics in sevoflurane-induced acute left ventricular depression in dogs.

OBJECTIVE: The purpose of this study was to compare the effects of dopamine and a new phosphodiesterase (PDE)-3 inhibitor, olprinone, on hemodynamics and myocardial energetics in dogs with acute myocardial depression. DESIGN: Prospective, randomized, crossover study. SETTING: University animal laboratory. SUBJECTS: Mongrel dogs. INTERVENTIONS: Eight open-chest, barbiturate-anesthetized dogs with instruments for measurement of left ventricular pressure and volume were exposed to 2 MAC (minimum alveolar concentration) of sevoflurane to induce acute myocardial depression. Each dog was randomly assigned for either infusion of dopamine (5 microg/kg/min) for 15 minutes or bolus of olprinone (10 microg/kg), followed by an infusion (0.3 microg/kg/min) for 30 minutes. Treatment was crossed over after a washout period of 90 minutes. MEASUREMENTS AND MAIN RESULTS: For analysis of ventricular energetics, ventriculoarterial coupling was assessed using the ratio of arterial elastance to end-systolic pressure-volume relation and mechanical efficiency was calculated using the ratio of external work to pressure-volume area. Measurements were performed prior to sevoflurane administration, and before and after treatment. Two MAC of sevoflurane significantly impaired ventriculoarterial coupling and mechanical efficiency. Both olprinone and dopamine improved ventriculoarterial coupling and mechanical efficiency to similar degrees, but by different mechanisms. Olprinone improved ventricular energetics at a lower energy expenditure, probably because of olprinone's vasodilating effect, which augments energy transfer from the ventricle into the systemic circulation. CONCLUSION: Although both dopamine and olprinone improve sevoflurane-induced impairment of ventricular energetics, olprinone accomplishes this with lower ventricular energy expenditure.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2006

Anesthetic management of a pediatric patient on a ketogenic diet.

There are several specific considerations regarding seizure control during the perioperative period in patients who have been placed on a ketogenic diet (KD). A KD is high in fat and low in protein and carbohydrates and has a long history of use for the treatment of intractable seizures in children. Maintaining therapeutic ketosis and modifying the acid-base balance are particularly important for preventing seizures in patients on a KD. We report changes in the biochemical parameters of a patient with double cortex syndrome who was on a KD and who had been scheduled for the treatment of dental caries under sevoflurane anesthesia and acetate Ringer administration. Inhalation induction with a high concentration of sevoflurane should be reconsidered in view of recent reports describing the epileptogenic potential of sevoflurane.

Anesthesia↗
PubMed2006

Different effects of transdermal and oral hormone replacement therapy on the renin-angiotensin system, plasma bradykinin level, and blood pressure of normotensive postmenopausal women.

BACKGROUND: This study compared the efficacy of transdermally administered estradiol with that of orally administered conjugated equine estrogens (CEE) on the renin-angiotensin system, plasma bradykinin level, and blood pressure (BP) in normotensive postmenopausal women (PMW). METHODS: A total of 38 normotensive PMW were randomly assigned to two groups. The transdermal hormone replacement therapy (HRT) group consisted of 19 women treated with a continuous transdermal estradiol patch (36 microg/day) plus cyclic oral medroxyprogesterone acetate (MPA; 2.5 mg/day for 12 days) for 12 months. The oral HRT group consisted of 19 women who received continuous oral CEE (0.625 mg/day) plus cyclic oral MPA (2.5 mg/day for 12 days) for 12 months. Plasma renin activity (PRA), serum angiotensin-converting enzyme (ACE) activity, plasma angiotensin (Ang) I, Ang II, and bradykinin concentrations, and BP were measured before and 12 months after the start of HRT. RESULTS: Transdermal HRT significantly decreased both diastolic and mean BP and concomitantly reduced bradykinin levels (all P < .05). However, no significant changes in PRA, ACE activity, Ang I, or Ang II levels were observed. The BP remained unchanged in the oral HRT group, but the PRA, Ang I, Ang II, and bradykinin levels had significantly increased and ACE activity had significantly decreased (all P < .05) at 12 months after the start of HRT. CONCLUSIONS: Transdermal HRT decreased BP in normotensive PMW without influencing Ang II, whereas oral HRT increased Ang II without altering BP. Transdermal HRT may be more beneficial than oral HRT with regard to BP and Ang II levels.

Administration, Cutaneous↗
PubMed2006

[Recovery from propofol anesthesia is delayed in hepatectomy patients due to altered pharmacodynamics].

BACKGROUND: Liver dysfunction has major impacts on the pharmacokinetics and pharmacodynamics of anesthetics. This study was designed to evaluate propofol concentrations during and at the end of total intravenous anesthesia (TIVA) for hepatectomy. METHODS: Fifty patients receiving hepatectomy (n = 25) or other epigastric surgeries (controls, n = 25) were anesthetized with TIVA. Fentanyl was injected repeatedly to insure maintenance of the effect-site concentration in the 2.0 to 2.5 ng x ml(-1) range with off line computer similation program. Propofol was administered with target-controlled infusion at the initial target concentration of 3.0 mcg x kg(-1), and then titrated to maintain bispectral index (BIS) values between 40 and 50. The intervals after propofol discontinuation to emergence and extubation and the predicted propofol and fentanyl concentrations were recorded. Propofol concentrations at emergence were measured with blood sample in eight cases. RESULTS: The propofol dose in hepatectomy patients as well as both measured and predicted concentrations of propofol at extubation, were lower than in control patients. The extubation time was longer in hepatectomy than in control subjects. CONCLUSIONS: Recovery from TIVA is delayed in hepatectomy patients. We speculate that this is attributable to altered pharmacodynamics in these patients.

Aged↗
PubMed2006

[The injection pain of propofol with different emulsion].

BACKGROUND: Incidence and intensity of pain on intravenous injection of propofol were assessed with emulsion of long-chain/medium-chain triglycerides (LCT/MCT, 50: 50) and only long-chain triglycerides (LCT, 100) in patients undergoing different elective surgical interventions in this prospective, randomized, cross over and double-blinded study. METHODS: 1) Forty six patients were assigned to two groups. One group received 0.2 mg x kg(-1) LCT/ MCT propofol prior to LCT propofol administration. The other group received 0.2 mg x kg(-1) LCT propofol prior to LCT/MCT propofol administration. Pain elicited upon questioning was assessed with each injection in the two groups. Patients were asked to grade the pain as VAS of 0 to 100 mm. 2) Fifty one patients were randomly assigned to two groups. One group received 0.4 mg x kg(-1) LCT propofol. The other group received 0.4 mg x kg(-1) LCT/MCT propofol. Patients were asked to grade the pain as VAS of 0 to 100 mm. RESULTS: Pain of LCT propofol injection was stronger than LCT/MCT propofol. As incidence of 0.4 mg x kg(-1) propofol injection, VAS on LCT/MCT propofol and LCT propofol gave score as 0 and 23.5 (P=0.0019). CONCLUSIONS: Propofol with emulsion of long- and medium-chain triglycerides appears to reduce the injection pain than with emulsion of only long-chain triglycerides.

Anesthesia, Intravenous↗
PubMed2006

[Neuromuscular blocking effects, pharmacokinetics and safety of Org 9426 (rocuronium bromide) in Japanese patients].

BACKGROUND: The purpose of this study was to examine pharmacodynamics, pharmacokinetics and safety of Org 9426 (rocuronium bromide) in Japanese patients. METHODS: Seventy-eight patients anesthetized with thiopental, droperidol, fentanyl and nitrous oxide, were randomized to receive either a single dose of Org 9426 0.3 mg x kg(-1), 0.6 mg x kg(-1) or 0.9 mg x kg(-1). Contraction of the adductor pollicis to the ulnar nerve stimulation (0.1 Hz) was measured by acceleromyography. Blood was sampled over 6 hr and pharmacokinetic variables were calculated by plasma concentrations of Org 9426. RESULTS: Onset times for patients receiving 0.3 mg x kg(-1), 0.6 mg x kg(-1) or 0.9 mg x kg(-1) were 271.5 s, 140.0s and 125.4s, respectively. There was a dose-dependent increase in clinical durations until 25% recovery of twitch height (17.4 min in 0.3 mg x kg(-1) group, 37.2 min in 0.6 mg x kg(-1) and 60.4 min in 0.9 mg x kg(-1) group). Pharmacokinetic study revealed that elimination half life, steady state volume of distribution and plasma clearance of Org 9426 were 48-76 min, 146-181 ml x kg(-1), and 3.8-4.5 ml x min(-1) x kg(-1), respectively. No adverse effects were found except a case of local erythema on a forearm. CONCLUSIONS: The efficacy of neuromuscular block, stable pharmacokinetic behavior and excellent safety of Org 9426 were also confirmed in Japanese surgical patients.

Adult↗
PubMed2006

[Anesthetic management of corpus callosotomy with electrophysiological monitoring: a case report].

We report anesthetic management of a 5-year-old girl for corpus callosotomy indicated for the treatment of intractable epilepsy. The procedure mandated intraoperative monitoring of evoked potentials and electrocorticogram. During the first half of the surgery until the corpus callosum was exposed, anesthesia was maintained with continuous infusion of propofol. Motor and somatosensory evoked potentials were monitored and diagnosed as intact throughout the procedure, with no epileptic activity observed in 32-lead electrocorticogram. Then propofol infusion was replaced with the inhalation of sevoflurane, 2.0% in air/oxygen mixture, which induced epileptic spike-and-wave activities, synchronized between the hemispheres, in electrocorticogram. After the completion of corpus callosotomy, we observed interhemispheric desynchronization of epileptic activities indicating successful surgical intervention. The patient emerged from anesthesia uneventfully with no neurological deficits, and thereafter with decreased incidence of generalized epileptic episodes. We suggest that such switch of anesthetic agents between propofol and sevoflurane should be helpful in intraoperative electrophysiological monitoring for ascertaining both functional preservation and successful intervention during epileptic surgery.

Anesthesia↗
PubMed2006

[Randomized, multicenter study of interaction between Org 9426 (rocuronium bromide) and anesthetic agents in Japanese population].

BACKGROUND: The purpose of this randomized, multi-center phase III trial was to investigate the influence of sevoflurane and propofol on the neuromuscular blocking effects and pharmacokinetic parameters of Org 9426 (rocuronium bromide) in Japanese population. METHODS: Thirty-nine adult Japanese patients participated in this randomized, multi-center study. Neuromuscular function was monitored continuously with TOF-Watch SX (Organon NV, Netherlands) after anesthetic induction with propofol. These subjects randomly received either 0.6 mg x kg(-1) or 0.9 mg x kg(-1) of rocuronium for endotracheal intubation. These two groups were further divided to two anesthetic regiments : sevoflurane group and propofol group. The difference in onset and recovery of rocuronium-induced neuromuscular block was statistically analyzed with two-way ANOVA. RESULTS: Mean duration for maximal block was 76 seconds and 66 seconds, respectively. The duration between Org 9426 administration and 25% recovery of first twitch response was significantly prolonged in patients given 0.9 mg x kg(-1) of Org 9426. Sevoflurane also significantly increased this duration. However, the serum concentration of Org 9426 was not statistically different between the four study groups. CONCLUSIONS: The duration of Org 9426-induced neuromuscular blockade was significantly increased under sevoflurane anesthesia compared to propofol anesthesia. This difference may be attributed to pharmacodynamic change.

Adult↗
PubMed2006

[Effects of sevoflurane and propofol on neuromuscular blocking action of Org 9426 (rocuronium bromide) infused continuously in Japanese patients].

BACKGROUND: The purpose of this study was to investigate the interaction of anesthetic agents with Org 9426 (rocuronium bromide) infused continuously. The effect of intubation dose of Org 9426 on its infusion rate was also investigated. METHODS: Total of 38 Japanese patients were randomly allocated either to receive intubation dose of 0.6 or 0.9 mg x kg(-1) of Org 9426. These patient groups were anesthetized with either sevoflurane or propofol. Infusion of Org 9426 was started with the initial infusion rate of 7 microg x kg(-1) x min(-1) when T1 reappeared after the intubation dose. The infusion rate was adjusted to keep the height of T1 between 3-10% of the control value. RESULTS: The rates of infusion 90 min after the start of infusion were 3.4, 7.5, 3.9 and 7.7 microg x kg(-1) x min(-1) for the 0.6 mg x kg(-1)-sevoflurane, 0.6 mg x kg(-1) propofol, 0.9 mg x kg(-1)-sevoflurane and 0.9 mg x kg(-1) propofol groups, respectively. Sevoflurane significantly reduced the infusion rate with both intubation doses. The mean infusion rates of 0.9 mg x kg(-1) groups were slower than those of 0.6 mg x kg(-1) groups up to 60 min after the start of infusion. Mean clearance of Org 9426 during infusion was not different between sevoflurane and propofol anesthesia. CONCLUSIONS: Patients receiving sevoflurane anesthesia required a markedly lower Org9426 infusion rate compared with patients receiving propofol anesthesia.

Adult↗
PubMed2006

[Evaluation of a compact device for capnometry of main-stream type compared with one of side-stream type in a postoperative care unit].

BACKGROUND: Pulse oximetry is insufficient for postoperative respiratory monitoring. It is better to use capnometry for postoperative patients because it is easy to use and useful to monitor patients' breathing. However, capnometry must be improved in its wearability and detection capability. Therefore it is not used often for postoperative patients as a respiratory monitor. METHODS: We have examined a side-stream type capnometer and an improved main-stream type capnometer in a post-anesthesia care unit (PACU) to determine which is better as a monitor for detection of breathing. A total of 55 patients participated in this study. Patients wore a device including a main-stream capnometer and a side-stream capnometer. Capnograms were recorded while patients were staying in the PACU. RESULTS: The main-stream system could detect breathing in all the patients, but the side-stream system failed to detect breathing in five patients. The side-stream device showed a warning of "apnea" for five patients, even though these patients were breathing normally. CONCLUSIONS: We conclude that the main-stream system is a better monitor of postoperative respiratory condition.

Capnography↗
PubMed2005

Propofol-mediated impairment of CA1 long-term potentiation in mouse hippocampal slices.

Propofol (2,6-diisopropylphenol) is a short-acting intravenous anesthetic. Propofol is known to impair maintenance of long-term potentiation (LTP) in synaptic responses from Schaffer collateral-commissural (SC) pathway to CA1 pyramidal cells in the hippocampus, but the threshold concentration of propofol needed to elicit this action is unknown. The actions of propofol in vivo (e.g., amnesia, sedation, hypnosis and immobility) depend on its concentration, and thus it is necessary to determine the concentration required to impair CA1 LTP in order to assess the impact of impairment in vivo. In the present study, we investigated the effects of various concentrations of propofol on synaptic plasticity, primarily by measuring LTP at SC pathway to CA1 pyramidal cell synapses in mouse hippocampal slices. Continuous application of 50 microM propofol from 20 min before tetanus stimulation suppressed potentiation of the synaptic responses by tetanus stimulation. The suppression was pronounced from 10 min post-tetanus and about 55% suppression of the potentiation was observed at 60 min after tetanus. Propofol at 5 or 20 microM did not have this effect. The presence of gamma-aminobutyric acid type A (GABA(A)) receptors antagonist, picrotoxin, abrogated the suppression of LTP by 50 microM propofol. Propofol 50 microM did not affect long-term depression (LTD). These results suggest that the suppression of hippocampal CA1 LTP via GABA(A) receptors requires a much higher propofol concentration compared with that needed to induce amnesia.

Action Potentials↗
PubMed2005

Cyclopropanation and carbonyl olefination utilizing 2-(Alk-1-yn-1-yl)-2-(trialkylsilyl)-1,3-dithianes via regioselective generation of titanium alkynylcarbene complexes.

Cp(2)Ti[P(OEt)(3)](2)-promoted reactions of 2-(alk-1-yn-1-yl)-2-(trialkylsilyl)-1,3-dithianes (RS)(2)C(Si)CCR with terminal olefins and carbonyl compounds produced (trialkylsilylethynyl)cyclopropanes and 1-(trialkylsilyl)alk-3-en-1-ynes, respectively. These compounds were suggest to be produced via the formation of intermediary titanium alpha-(trialkylsilylethynyl)carbene complexes Cp(2)Ti=C(R)CCSi in preference to their regioisomers, alpha-(trialkylsilyl)alkynylcarbene complexes Cp(2)Ti=C(Si)CCR.

Journal Article↗
PubMed2005

Effects of colloid resuscitation on peripheral microcirculation, hemodynamics, and colloidal osmotic pressure during acute severe hemorrhage in rabbits.

We examined the effects of hydroxyethyl starch (HES) on the microcirculation, hemodynamics, and colloidal osmotic pressure in a rabbit model of hemorrhagic shock. A total of 40 rabbits was anesthetized with pentobarbital and isoflurane, and they were mechanically ventilated. An ear chamber was prepared to examine blood vessels by intravital microscopy. Shock was induced by removing nearly half of the circulating blood volume. Twenty rabbits received 20 mL of HES by intravenous infusion immediately after blood letting. Additional HES was then administered intravenously to a total volume of 100 mL. The other 20 rabbits (control) were intravenously given 40 mL of lactated Ringer's solution (LR), followed by additional LR to a total volume of 200 mL, administered under the same conditions as HES. After blood letting, arteriolar diameter decreased similarly in the the HES and LR groups (HES, 40.5% +/- 14.8% of the baseline value versus LR, 43.3% +/- 13.1%). After the completion of infusion, arteriolar diameter significantly recovered to 90.8% +/- 10.2% of the baseline value in the HES group as compared with only 62.6% +/- 10.7% in the LR group (P < 0.005). Recovery of arterial blood flow velocity and blood flow rate was also significantly better in the HES group than in the LR group (P < 0.005). Mean arteriolar pressure, central venous pressure, and plasma colloid osmotic pressure after the completion of infusion were significantly greater in the HES group than in the LR group (P < 0.005). We conclude that intravenous infusion of HES effectively maintains the microcirculation, hemodynamics, and colloidal osmotic pressure in a rabbit model of acute severe hemorrhage.

Animals↗
PubMed2005

Individual effect-site concentrations of propofol are similar at loss of consciousness and at awakening.

Reported effect-site concentrations of propofol at loss of consciousness and recovery of consciousness vary widely. Thus, no single concentration based on a population average will prove optimal for individual patients. We therefore tested the hypothesis that individual propofol effect-site concentrations at loss and return of consciousness are similar. Propofol effect-site concentrations at loss and recovery of consciousness were estimated with a target-control infusion system in 20 adults. Propofol effect-site concentrations were gradually increased until the volunteers lost consciousness (no response to verbal stimuli); unconsciousness was maintained for 15 min, and the volunteers were then awakened. This protocol was repeated three times in each volunteer. Our major outcomes were the concentration producing unconsciousness and the relationship between the estimated effect-site concentrations at loss and recovery of consciousness. The target effect-site propofol concentration was 2.0 +/- 0.9 at loss of consciousness and 1.8 +/- 0.7 at return of consciousness (P <0.001). The average difference between individual effect-site concentrations at return and loss of consciousness was only 0.17 +/- 0.32 microg/mL (95% confidence interval for the difference 0.09-0.25 microg/mL). Our results thus suggest that individual titration to loss of consciousness is an alternative to dosing propofol on the basis of average population requirements.

Adult↗
PubMed2005

A single local application of recombinant human basic fibroblast growth factor accelerates initial angiogenesis during wound healing in rabbit ear chamber.

Local angiogenic therapy with recombinant human basic fibroblast growth factor (rhbFGF) has been used to promote wound healing. To obtain useful information for the development of optimal angiogenic therapy, we chronologically evaluated the effects of a single local application of rhbFGF on angiogenesis in a rabbit ear chamber model of wound healing by observing the subcutaneous vessel bed intravitally. New vessel formation during wound healing was macroscopically and microscopically evaluated for 5 wk. Each rabbit ear chamber received a single dose of 6 microg rhbFGF (treatment B1: n = 13), 18 microg rhbFGF (treatment B2: n = 16), or physiological saline as control (n = 13). At 1 wk the newly vascularized area was significantly larger in groups B1 and B2 than in control. At 2 wk, the vascularized areas in groups B1, B2, and control were similar. At 5 wk, the percentage of rabbits with complete vascularization was significantly larger in group B1 than in control. Capillary density at 5 wk was similar among the three groups. These results suggest that locally applied rhbFGF accelerated angiogenesis during early wound healing in rabbits; however, this effect was transient and no increase in capillary density occurred at the completion of vascularization.

Administration, Topical↗
PubMed2005

[Evaluation of our manual for prevention of perioperative pulmonary embolism].

All patients scheduled for surgical procedures were divided into three groups depending on risk grade for pulmonary embolism (PE) in our hospital from August, 2001. Based on our experience of two PE cases after gynecologic surgery, we introduced the perioperative manual for prevention of PE from April, 2003. According to the manual criteria, we could decide indications for the physical prophylaxis or anticoagulant preventive treatment for the patients. In spite of introduction of the manual, two cases of PE occurred after femoral head prosthetic replacement for femoral head fracture patients classified low risk group in our criteria. The Japanese guideline for prevention of venous thromboembolism was published in January, 2004, but even low risk group patients were candidates for PE depending on the surgery and the situation. Even after installation of the guideline for PE, careful perioperative examination is mandatory to prevent and treat PE.

Adult↗