Biomedical subjects

O Kemmotsu

Publications and source records attributed to O Kemmotsu.

At least 73 records · Page 4Linked to original sources

PubMed1997

Comparison of tympanic, esophageal and blood temperatures during mild hypothermic cardiopulmonary bypass: a study using an infrared emission detection tympanic thermometer.

OBJECTIVE: Tympanic temperature can be obtained instantaneously using an infrared emission detection (IRED) thermometer. Its accuracy has been documented in a variety of clinical settings, but its performance at low body temperatures is still unknown. In this study we evaluated its performance during coronary artery revascularization surgery in which mild hypothermic cardiopulmonary bypass (CPB) was used. METHODS: Thirty adult patients undergoing coronary artery bypass graft surgery were enrolled in the study. Tympanic temperature obtained using IRED thermometry (Tt1) was compared with core temperatures from the esophagus (Te), and venous blood of CPB (Tv) before, during, and after CPB. We also measured tympanic temperature using a thermocouple probe (Tt2) in 16 of the 30 patients in order to study the agreement between the two methods. Values for correlation coefficients and limits of agreement were computed to assess the degree of agreement among the temperatures obtained. RESULTS: The highest agreement with Tv during CPB was obtained from Tt1 (r = 0.94, 0.41 +/- 1.73, limits of agreement) and from Te (0.91, 0.36 +/- 2.46). Tt1 also showed good agreement with Tt2 during surgery. CONCLUSIONS: Infrared tympanic thermometry is a reliable, alternative method to measure tympanic temperature and may be useful to assess core temperature in both normothermic and mild hypothermic conditions.

Adult↗

PubMed1997

Characterization of adenosine receptors mediating spinal sensory transmission related to nociceptive information in the rat.

BACKGROUND: Adenosine analogs have been shown to produce antinociception after intrathecal administration. To determine the adenosine receptor subtype involved in spinal antinociception, the effects of selective agonists and an antagonist on the evoked potentials recorded from a neonatal rat spinal cord were studied. The measured potentials are a slow ventral root potential (slow VRP), which is the C-fiber-evoked excitatory response associated with nociceptive information; a monosynaptic reflex (MSR), which reflects a non-nociceptive transmission related to motor function; and a dorsal root potential (DRP), which reflects a gamma-aminobutyric acidA (GABA(A)) receptor-mediated presynaptic inhibition associated with analgesia. METHODS: The evoked potentials were recorded in response to electric stimulation of a lumbar dorsal root. Dose-response curves of agonists for these responses were obtained to determine their relative potency order. The antagonist dissociation constants (K(D) values) were estimated by Schild analysis. RESULTS: Adenosine agonists dose dependently inhibited the slow VRP and the MSR. However, the slow VRP was five to eight times more sensitive to them than was the MSR. The rank order of agonist potency was N6-cyclohexyladenosine (CHA) = N6-(R)-phenylisopropyladenosine (R-PIA) > 5'-N-ethylcarboxamidoadenosine (NECA) >> CGS 21680 in both responses. 8-Cyclopentyltheophylline produced dose-dependent parallel shifts to the right of NECA dose-response curves for these responses. Schild analysis gave linear plots with slopes near unity. The K(D) values of CPT for the MSR and the slow VRP were estimated to be 5.5 nM and 4.3 nM, respectively. The DRP was also depressed by adenosine agonists with potency order of CHA > NECA >> CGS 21680. 8-Cyclopentyltheophylline antagonized the inhibitory effects of CHA on the DRP. CONCLUSIONS: The results indicate that adenosine agonists inhibit spinal sensory transmission related to nociception by acting at the A1 receptors. The A1 receptor also seems to be involved in transmission related to the spinal motor system. Feedback inhibition mediated by GABA(A) receptors does not contribute to this antinociceptive action.

Adenosine↗

PubMed1997

Extracellular acidosis delays cell death against glucose-oxygen deprivation in neuroblastoma x glioma hybrid cells.

OBJECTIVE: To determine whether extracellular acidosis delays cell death against glucose-oxygen deprivation and, if so, whether this result is due to inhibition of calcium (Ca2+) influx or preservation of cellular energy state. DESIGN: Randomized, controlled, prospective study. SETTING: University research laboratory. SUBJECTS: Differentiated neuroblastoma x glioma NG108-15 cells. INTERVENTIONS: Experiment 1: cells were incubated for 8 hrs in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid-buffered medium under glucose-oxygen deprivation at pH 7.4, 6.8, 6.5, 6.2, 5.6, or 5.0. Experiment 2: cells were incubated for 8 hrs under glucose-oxygen deprivation after excluding extracellular calcium from culture medium at pH 7.4 or 6.2. Experiment 3: cells were incubated for 2, 4, 6, or 8 hrs in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid-buffered medium under glucose-oxygen deprivation at pH 7.4 or 6.2 and assayed for high-energy phosphates. MEASUREMENTS AND MAIN RESULTS: Cell viability was measured with flow cytometry after the cells were stained with fluorescein diacetate and propidium iodide. Cellular adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate were analyzed with high-performance liquid chromatography. Cell viability was significantly greater at pH 6.2 than at pH 7.4 in experiment 1. By excluding extracellular calcium, a significant difference in viability between pH 7.4 and 6.2 persisted in experiment 2. Energy charge and the concentration of adenosine triphosphate were significantly greater at pH 6.2 than at pH 7.4 in the intervals preceding manifestation of a differential effect of acidosis on cell viability in experiment 3. CONCLUSIONS: Extracellular acidosis at pH 6.2 delayed cell death against glucose-oxygen deprivation. This protective effect by extracellular acidosis may be due to preservation of the cellular energy state in NG108-15 cells, although this study does not exclude the possibility that in other cell types, inhibition of calcium influx may have an effect.

Acidosis↗

PubMed1997

Feasibility of urodynamic study (combined cystometry and electromyography of the external urethral sphincter) under general anesthesia in children.

BACKGROUND: To assess the feasibility of urodynamic study under general anesthesia (GA) we performed electromyography of the external urethral sphincter (EUS-EMG) on 73 children and cystometry (CM) alone on 10 children. METHODS: Subjects were divided into 3 groups. Those in groups I and II were suspected of having voiding dysfunction with (group I) or without (group II) overt neurospinal defects, while those in group III were thought to be functionally normal. EUS-EMG was performed under light anesthesia following cystourethroscopy to examine structural abnormalities. Atropine sulfate premedication was not used for the anesthetic procedure; muscle relaxants were used only for tracheal intubation. RESULTS: Voiding was observed in 83% of the patients. Among patients who voided, detrusor-external sphincter dyssynergia (DSD) was noted in 7 (38%) group I patients and 6 (19%) group II patients; in group III, voiding was synergic in all patients. In 10 cases, CM alone was carried out both under anesthesia and in the waking state; anesthesia suppressed detrusor hyperreflexia (DH) in all 9 patients but produced no change in bladder compliance. CONCLUSIONS: In children with urinary disorders, urodynamic study under GA following cystourethroscopy is a feasible method for assessing EUS function and documenting DSD; DH is not evaluable, however. Stratifying urinary management on the basis of these examinations resulted in satisfactory clinical outcomes.

Adolescent↗

PubMed1997

[A psychological burden on patients with clinical trials during anesthesia].

We investigated with questionnaires, psychological outline of 30 patients, who were requested to participate in clinical trials of anti-tachycardia drugs during anesthesia. Although 14 patients consented to the trial, the consent was not based on adequate understanding or volunteerism in 3 patients. Nine patients of the consented group were anxious about the possible use of the trial drug. Eight patients of the rejected group felt anxiety on surgery and anesthesia, which was the most common reason for rejection. Forty % of refused patients felt a guilty conscience or embarrassed. Although we tried to obtain patients' consent following governmental and institutional regulations and guidelines, not only the consented but also the refused patients suffer from psychological burden with the clinical trial. It is of concern that recruitment to the trial enhances anxiety of the patients as they already feel uneasiness, unrest, and insecurity facing anesthesia and surgery. To avoid entry of less informed or unwilling patients to the clinical trial, we must secure patients' veto, and recruitment should be performed by clinicians who are not involved in anesthesia practice.

Anesthesia↗

PubMed1997

[Automated anesthesia record keeping system in in the United States].

We have implemented an automated anesthesia record keeping system (AARK) since 1992. The system stands in need of re-designing to function as a perioperative patient's information system. We discussed the issues with anesthesiologists who's institutes are implemented with AARK in the United States. We visited the following three institutes: St. Luke's Hospital (Kansas City, MO), University of Florida (Gainesville, FL), and Burbank Hospital (Fitchburg, MA). All of them are implemented with ARKIVE system. Dr. Edsall in Burbank Hospital stressed quality assurance (QA), and using ARKIVE's database for QA. University of Florida has a big anesthesia and engineering team to develop a new ergonomically sound AARK. Some of the members regarded ARKIVE as an "out of date" system. Dr. Tuohy in St. Luke's Hospital stressed cost/benefit of AARK. Taking their experience into account, we are designing a new perioperative patient's information system including AARK.

Anesthesia↗

PubMed1997

[Successful use of propofol for anesthesia for plasty of eyelids in epidermolysis bullosa].

A 21-year-old male with recessive dystrophic epidermolysis, required anesthesia for plastic surgery of eyelids. We took special care for the attachment of monitoring equipment and placing an intravenous cannula. Anesthesia was induced by intravenous propofol 1 mg.kg-1 and maintained with local injection of 1.0% lidocaine and continuous infusion of propofol 3-4 mg.kg-1.hr-1. Tracheal intubation was not performed and oxygen was given through a nasal cannula and spontaneous breathing was maintained throughout the anesthetic management. Respiratory condition was monitored by measuring Spo2 and end-tidal CO2 by capnography obtained from the nasal cannula. Operation was performed successfully and he was discharged without any major complications.

Adult↗

PubMed1996

The effects of sevoflurane on contractile and electrophysiologic properties in isolated guinea pig papillary muscles.

We examined, in guinea pig papillary muscles, whether the negative inotropic effect of sevoflurane is due to the depression of the influx of extracellular Ca2+ or to inhibition of the availability of intracellularly stored Ca2+. Sevoflurane decreased action potential duration and contractile force in a concentration-dependent fashion in normally polarized guinea pig papillary muscles. Sevoflurane produced a depression of contractile force with different rates or patterns of stimulation in the rested state and at low stimulation frequencies. In a potentiated state, sevoflurane did not depress contractile forces. Although sevoflurane decreased action potential duration and contractile force in a concentration-dependent fashion in normal Tyrode's solution, in high K+ Tyrode's solution, it caused a depression of contractile force without a shortening of action potential duration. Sevoflurane also depressed contractile force in normal and high K+ Tyrode's solution with ryanodine 1 microM. Our results suggest that in myocardial contractile force the negative inotropic effect of sevoflurane might be caused by depression of transsarcolemmal Ca2+ influx, accompanied by shortening of the action potential duration.

Action Potentials↗

PubMed1996

Mechanism of cellular swelling induced by extracellular lactic acidosis in neuroblastoma-glioma hybrid (NG108-15) cells.

The mechanism of cellular swelling induced by extra-cellular lactic acidosis and the effect of diuretics were studied using neuroblastoma-glioma hybrid (NG108-15) cells. The cells were incubated in one of three lactate concentrations (0, 15, or 30 mM), each of which was randomized to one of three pH groups (7.4, 6.2, or 5.0). Analysis of the swelling was measured using a Coulter counter technique. Cellular swelling was most prominent at pH 6.2 at all lactate levels. Cellular swelling was noted to be pH dependent but not lactate dependent. The addition of 1 mM amiloride completely blocked cellular swelling, suggesting that the main mechanism of neuronal cellular swelling induced by extracellular lactic acidosis was the activation of Na+/H+ exchange. Second, three dissimilar diuretic drugs were used for cellular swelling: amiloride (Na+/H+ exchange inhibitor), mannitol (osmotic diuretic), and bumetanide (loop diuretic). Amiloride and mannitol were found effective in reducing the lactic acidosis-induced cellular swelling. Furthermore, the combination of these drugs had additive effects. However, bumetanide was not effective. The results indicate that the direct inhibition of Na+/H+ exchange and/or removal of water from the cell by mannitol was effective against cellular swelling induced by the activation of Na+/H+ exchange in NG108-15 cells.

Acidosis, Lactic↗

PubMed1996

Extramyocardial acidosis impairs cardiac resuscitability in isolated, perfused, rat hearts.

OBJECTIVES: Patients suffering out-of-hospital cardiac arrest have various degrees of acidemia when cardiopulmonary resuscitation is initiated. Myocardial hypercarbia, rather than decreases in myocardial pH, may determine cardiac resuscitability. Accordingly, we questioned whether different degrees of acidemia accompanying cardiac arrest affect cardiac resuscitability. We evaluated the effect of different degrees of extramyocardial acidosis on cardiac performance and resuscitability after ventricular fibrillation using isolated, perfused, rat hearts. DESIGN: Prospective, randomized, controlled study. SETTING: Experimental animal laboratory in a university hospital. SUBJECTS: Thirty-one male, Sprague-Dawley rats. INTERVENTIONS: Rat hearts were perfused with N-[2-hydroxyethyl]piperazine-N-[2-ethanesulfonic acid] (HEPES) buffered solution (sodium chloride 145 mM, potassium chloride 4 mM, sodium dihydrogen phosphate dihydrate 1.25 mM, magnesium chloride 1.5 mM, calcium chloride 2 mM, HEPES 6 mM, glucose 10 mM), which was bubbled with 100% oxygen and adjusted to a pH of 7.4. The perfusion pressure was held constant at 60 mm Hg. After 60 mins of stabilization, the control perfusion solution was switched to one of the solutions titrated to pH 6.2, 6.5, 6.8, 7.1, or 7.4, using 1 N of sodium hydroxide. Hearts were allocated randomly to each group. After 15 mins of perfusion, the perfusion was discontinued, and artificial ventricular fibrillation was induced by electrical stimulation for 5 mins. The hearts were then perfused again in one of the same acidotic solutions for 30 mins. MEASUREMENTS AND MAIN RESULTS: Left ventricular developed pressure (left ventricular pressure minus end-diastolic left ventricular pressure), positive change in left ventricular pressure over time, heart rate (HR), and coronary flow were continuously measured. After 60 mins of stabilization, the values of left ventricular developed pressure, positive change in left ventricular pressure over time, HR, and coronary flow were not significantly different between groups. After 5 mins of ventricular fibrillation, all hearts were asystolic and left ventricular developed pressure, positive change in left ventricular pressure over time, HR, and coronary flow were all zero. After 30 mins of reperfusion, all values in the acidotic groups were significantly lower than the values in the pH 7.4 group. When we judged the recovery of left ventricular developed pressure at > 35 mm Hg as "resuscitated," resuscitability was impaired at a pH of < 7.1. No hearts recovered after perfusion below a pH of 6.5. CONCLUSIONS: Extramyocardial acidosis below pH 7.1 decreased cardiac performance and resuscitability after ventricular fibrillation. This result indicates that progressive acidemia during cardiac arrest is one of the important determinants of cardiac resuscitability.

Acidosis↗

PubMed1996

[Effects of halothane, isoflurane, enflurane, and sevoflurane on the monosynaptic reflex response in the isolated spinal cord of newborn rats].

Monosynaptic reflex responses (MSRs) in the isolated spinal cord of newborn rats were elicited in the ventral root by stimulation of the ipsilateral dorsal root. MSRs were considered to be mediated by non-NMDA class glutamate receptors. We studied the depressant effects of halothane, isoflurane, enflurane, and sevoflurane on MSR amplitudes as a function of anesthetic concentration comparing with MAC value of each anesthetics. The spinal cord of newborn rats were rapidly dissected out, and placed in a chamber superfused with artificial cerebrospinal fluid (ACSF, pH 7.4, 34 degrees C) equilibrated with 95% O2 - 5% CO2. Anesthetic gases were delivered with specific vaporizers and bubbled in the ACSF. Each anesthetic concentration was determined by gas chromatography. Either of the anesthetics reversibly depressed MSR amplitudes in a concentration dependent fashion. Concentration-response curves for MSR amplitudes were constructed and the concentrations which produced a half-maximum inhibition (IC50) were 0.56, 0.65, 0.97 and 1.18 mM for halothane, isoflurane, enflurane, and sevoflurane, respectively. These IC50 values correlated well with those of MAC values (r = 0.999, P < 0.001) obtained from adult rats in an in vivo condition. The MSR response in the isolated spinal cord of newborn rats is considered as a useful model for analysis of potency of volatile anesthetics.

Anesthetics, Inhalation↗

PubMed1996

[Delayed rupture of a balloon reservoir in a disposable infusion pump].

We experienced delayed rupture of a balloon reservoir in a disposable infusion pump 3 hours after filling. The investigation revealed a sharp scratch in the reservoir. Furthermore, as we did not filtrate the drugs before filling, we speculate that ampule fragments could have provoked the rupture. When filling a disposable infusion pump with ampule solution, filtration against glass contamination is recommended.

Analgesics, Opioid↗

PubMed1995

Pharmacological characterization of alpha 2-adrenoceptor regulated serotonin release in the rat hippocampus.

The purpose of the present study was to confirm the functional regulation by alpha 2-adrenoceptors of the release of serotonin (5-HT) from the rat hippocampus in vivo. Under several pharmacological conditions, extracellular levels of 5-HT were estimated by assaying its concentrations in the perfusate by high performance liquid chromatography with electrochemical detection. Extracellular 5-HT in the hippocampus was reduced by tetrodotoxin (10 microM) co-perfusion, but increased by perfusion of a selective 5-HT re-uptake inhibitor, fluoxetine (10 microM). Addition of potassium (K+, 120 mM) to the perfusion fluid evoked an approximately 3-fold increase in 5-HT release. When the alpha 2-adrenoceptor agonist UK14,304 (0.1-10 microM) was added to the perfusion solution, the K(+)-evoked 5-HT release was significantly inhibited in a concentration-dependent manner. This inhibitory action of UK14,304 was reversed by pretreatment with an alpha 2-adrenoceptor antagonist, idazoxan (5 mg/kg, i.p.). In rats which were catecholaminergically denervated with 6-hydroxydopamine, UK14,304 (10 microM) still inhibited the K(+)-evoked 5-HT release. Treatment with pertussis toxin (PTX) did not alter the K(+)-evoked release of 5-HT but abolished the inhibitory effect of UK14,304. These findings suggest that 5-HT release is functionally modulated via alpha 2-adrenoceptors located on the serotonergic nerve terminals in the rat hippocampus and furthermore, the possibility that the inhibitory of alpha 2-adrenoceptors is linked to G-proteins which are substrates of PTX.

Adrenergic alpha-2 Receptor Agonists↗

PubMed1995

Secondary hyperparathyroidism shortens the action of vecuronium in patients with chronic renal failure.

The authors studied the duration of action of vecuronium in 15 patients with normal renal function and 40 patients with chronic renal failure to evaluate the effect of secondary hyperparathyroidism on the action of vecuronium. The patients were divided into four groups: 15 patients with normal renal function (Group A); nine patients with chronic renal failure who did not need haemodialysis (Group B); 15 anephric patients who did not require parathyroidectomy (Group C); and 16 anephric patients who underwent parathyroidectomy because of severe secondary hyperparathyroidism (Group D). The ratio of the height of the first twitch (T1) to the baseline value before vecuronium administration was measured by an electromyogram. Baseline T1 was obtained after anaesthesia induction with thiamylal iv. The time to 10% recovery of the first twitch (REC 10) after administration of vecuronium 0.12 mg.kg-1 iv was measured in each group. Anaesthesia was maintained with isoflurane and nitrous oxide in oxygen, and supplemented with fentanyl iv. Patients in Group D showed shorter REC 10 (51 +/- 4 min) than those in Groups B (71 +/- 6 min) and C (80 +/- 10 min) (P < 0.05), but similar REC 10 to patients in Group A (37 +/- 4 min). These results suggest that the duration of action of vecuronium in anephric patients with secondary hyperparathyroidism is shorter than in those without secondary hyperparathyroidism.

Anesthesia, Inhalation↗

PubMed1995

Comparison of cardiovascular responses to airway management: fiberoptic intubation using a new adapter, laryngeal mask insertion, or conventional laryngoscopic intubation.

STUDY OBJECTIVES: To evaluate the circulatory effects of fiberoptic intubation with a newly developed mask adapter and to compare these effects with those obtained with a conventional laryngoscope and laryngeal mask airway with general anesthesia. DESIGN: Randomized study. SETTING: Operating room at a university hospital. PATIENTS: 30 ASA physical status I adult patients scheduled for minor elective surgery. INTERVENTIONS: A Macintosh laryngoscope was used for intubation in Group L (n = 10), a fiberoptic bronchoscope with newly developed mask adapter was used in Group FI (n = 10), and a laryngeal mask airway was used in Group LMA (n = 10). Anesthesia was induced with thiamylal, fentanyl, and vecuronium. Patients were manually ventilated for 4 minutes with sevoflurane. Then their tracheas were intubated with a laryngoscope or fiberoptic bronchoscope, or a laryngeal mask airway was inserted. MEASUREMENTS AND MAIN RESULTS: Blood pressure (BP) and heart rate (HR) were measured continuously. After intubation, the magnitude of change of both BP and HR was greatest in Group L, next highest in Group FI, and lowest in Group LMA. CONCLUSION: Fiberoptic intubation with general anesthesia using the newly developed mask adapter offers an advantage over the standard laryngoscope for patients in whom pressor response of intubation is potentially hazardous.

Adult↗

PubMed1995

Activity changes in rat raphe magnus neurons at different concentrations of fentanyl in vitro.

The nucleus raphe magnus (NRM) is an important descending pain inhibitory system. We postulated that the analgesic action of supraspinally administered opiates results from increased descending inhibitory control of the NRM. We tested whether fentanyl activates NRM neurons in the rat slice preparation using extra-cellular recording. Eighty-seven percent of NRM neurons (total number = 68) tested were spontaneously active with firing frequencies of 0.2-4 spikes/s in artificial cerebrospinal fluid. Application of fentanyl (0.25, 0.5, and 1 mumol/L) increased firing frequencies in 12 of 59 (20%) spontaneously active neurons. In 6 of 9 (67%) silent neurons, fentanyl induced firing activities. Naloxone (1-2 mumol/L) antagonized the increased or induced activities by fentanyl in three neurons. In 13 of 59 (22%) spontaneously active neurons, fentanyl decreased the firing frequencies. Although fentanyl was associated with increased activity in a total of 18 NRM neurons, fentanyl at a higher concentration significantly increased the number of inhibited neurons. The results indicate that fentanyl partly activates the descending inhibitory system originating from the NRM; however, at higher concentrations, it appears also to inhibit this same system.

Action Potentials↗

PubMed1995

[Finding appropriate tube position by the cuff palpation method in children].

The present study was designed to examine whether palpation of the endotracheal tube cuff indicates appropriate positioning in the children. In 59 children, we used a cuffed endotracheal tube (3.5-5 mm ID) to measure the distance from the carina to the distal tip of the endotracheal tube, when we can palpate the endotracheal tube cuff between the cricoid cartilage and the suprasternal notch. Following slow induction of anesthesia and muscle relaxation, each patient was intubated with a cuffed endotracheal tube of size suitable for age. The cuff was inflated with 0.5-1 ml of air, and palpated between the cricoid cartilage and the suprasternal notch. The distance between the carina and the tube tip measured by a fiberscope was more than 1.0 cm, which is thought to be safe to prevent bronchial intubation. The cuff was deflated after measurement. There were no complications attributable to use of cuffed endotracheal tubes. We concluded that the cuff palpation method was a rapid, reliable and simple technique to ensure the proper tube position in children.

Child↗

PubMed1995

[The duration of action of vecuronium in five patients after kidney transplantation--comparison with that during kidney transplantation].

We compared the duration of vecuronium action in five patients after the kidney transplantation with that during kidney transplantation. After the transplantation, three patients required no hemodialysis therapy but two patients underwent hemodialysis therapy again. In all these five patients, including patients who were back to hemodialysis therapy, the durations of vecuronium action after receiving transplanted kidney were shorter than those during kidney transplantation. These shortened durations are speculated to be mainly due to excretion of vecuronium by the transplanted kidney and the effect of long term steroid therapy. However in this study the durations of vecuronium action in patients who required further hemodialysis therapy were also shorter than those during kidney transplantation. To determine whether this is a common or exceptional phenomenon, further evaluation should be needed.

Adult↗