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Biomedical subjects

Takahisa Goto

Publications and source records attributed to Takahisa Goto.

13 recordsLinked to original sources
PubMed2006

A1 adenosine receptor-mediated modulation of neuronal ATP-sensitive K channels in rat substantia nigra.

ATP-sensitive K (K(ATP)) channels, widely expressed in cytoplasmic membranes of neurons, couple cell metabolism to excitability. They are considered to play important roles in controlling seizure activity during hypoxia and in neuroprotection against cell damage during hypoxia, ischemia and excitotoxicity. It is known that adenosine augments the opening of cardiac surface K(ATP) channels by reducing the sensitivity of these channels to ATP blockade. We investigated whether a similar modulation occurs in neuronal channels. Whole cell voltage-clamp recordings were made using rat midbrain slices to record the membrane current and conductance in principal neurons of the substantia nigra pars compacta (SNc). When the pipette solution contained 1 mM ATP, the membrane current at -60 mV and cellular conductance remained stable for at least 15 min. When slices were treated with (-)-N(6)-2-phenylisopropyl adenosine (R-PIA), a selective agonist for A(1) adenosine receptors, in the same condition, the outward current developed slowly to the amplitude of 109.9+/-26.6 pA, and conductance increased to 229+/-50% of the baseline. These changes were strongly inhibited by 200 microM tolbutamide, a K(ATP) channel blocker, suggesting that opening of K(ATP) channels mediated these changes. Pretreatment with 8-cyclopentyltheophylline (CPT), a selective A(1) adenosine receptor antagonist, abolished the outward current and conductance increases. Treatment of adenosine resulted in the similar changes sensitive to tolbutamide. These changes were abolished by CPT. These results suggest that activation of A(1) adenosine receptors promotes the opening of K(ATP) channels in principal neurons of the SNc by removing the blockade by ATP.

Adenosine↗
PubMed2006

High tidal volume ventilation induces lung injury after hepatic ischemia-reperfusion.

Ischemia-reperfusion not only damages the affected organ but also leads to remote organ injuries. Hepatic inflow interruption usually occurs during hepatic surgery. To investigate the influence of liver ischemia-reperfusion on lung injury and to determine the contribution of tidal volume settings on liver ischemia-reperfusion-induced lung injury, we studied anesthetized and mechanically ventilated rats in which the hepatic inflow was transiently interrupted twice for 15 min. Two tidal volumes, 6 ml/kg as a low tidal volume (IR-LT) and 24 ml/kg as a high tidal volume (IR-HT), were assessed after liver ischemia-reperfusion, as well as after a sham operation, 6 ml/kg (NC-LT) and 24 ml/kg (NC-HT). Both the IR-HT and IR-LT groups had a gradual decline in the systemic blood pressure and a significant increase in plasma TNF-alpha concentrations. Of the four groups, only the IR-HT group developed lung injury, as assessed by an increase in the lung wet-to-dry weight ratio, the presence of significant histopathological changes, such as perivascular edema and intravascular leukocyte aggregation, and an increase in the bronchoalveolar lavage fluid TNF-alpha concentration. Furthermore, only in the IR-HT group was airway pressure increased significantly during the 6-h reperfusion period. These findings suggest that liver ischemia-reperfusion caused systemic inflammation and that lung injury is triggered when high tidal volume ventilation follows liver ischemia-reperfusion.

Animals↗
PubMed2006

Hypertension and anesthesia.

PURPOSE OF REVIEW: There are still many controversies about perioperative management of hypertensive patients. This review aims to provide relevant instruction based on evidence regarding the treatment of those patients. RECENT FINDINGS: Mild to moderate hypertension is not independently responsible for perioperative cardiac complications. The position is less clear for severely hypertensive patients. A randomized study shows no benefit of the traditional practice of delaying elective surgery in severely hypertensive patients until better control of blood pressure is achieved. Perioperative use of beta-blockers or alpha-2 agonists has been shown to maintain perioperative hemodynamic stability and thereby to prevent major cardiac complications. SUMMARY: Delaying surgery only for the purpose of blood pressure control may not be necessary, especially in the case of mild to moderate hypertension. Strict care, however, should be taken to ensure perioperative hemodynamic stability because labile hemodynamics, rather than preoperative hypertension per se, appears to be more closely associated with adverse cardiovascular complications. Delaying surgery in hypertensive patients may be justified if target organ damage exists that can be improved by such a delay or if (suspected) target organ damage should be evaluated further before the operation.

Anesthesia↗
PubMed2006

The effects of xenon on myogenic motor evoked potentials in rabbits: a comparison with propofol and isoflurane.

We compared the effects of xenon on myogenic motor evoked potentials (MEPs) with those of propofol and isoflurane in rabbits under ketamine/fentanyl anesthesia. Thirty animals were randomly allocated to one of 3 groups (n = 10 in each group). In the propofol group, propofol was administered at a rate of 0.4 mg x kg(-1) x min(-1) (small) and 0.8 mg x kg(-1) x min(-1) (large). In the isoflurane group, isoflurane was administered at 0.8% (small) and 1.6% (large). In the xenon group, xenon was administered at 35% (small) and 70% (large). Myogenic MEPs in response to stimulation with single pulse and a train of 5 pulses were recorded from the soleus muscle before, during (at small and large doses), and after the administration of each anesthetic. With single-pulse stimulation, MEPs were recorded in 90% and 50% of animals at small and large doses of xenon, respectively, and MEP amplitudes in the xenon and isoflurane groups were significantly lower compared with those in the propofol group. With train pulse stimulation, MEPs were recorded in 100% and 90% of animals at small and large doses of xenon, respectively, and a reduction in MEP amplitudes by xenon was more prominent than by propofol but less than isoflurane at large doses. These results suggest that MEP recording may be feasible under xenon anesthesia if multipulse stimulation is used, although xenon has suppressive effects on myogenic MEPs.

Anesthetics, Inhalation↗
PubMed2005

The bispectral index predicts responsiveness to verbal commands in patients emerging from nitrous oxide anesthesia supplemented with a subhypnotic concentration of isoflurane.

PURPOSE: Nitrous oxide (N2O) administered alone has minimal effects on the bispectral index (BIS), an electroencephalogram-derived parameter of hypnosis. However, because this gas is commonly supplemented with a volatile anesthetic, we sought to determine how it would affect the BIS when coadministered with a low concentration of isoflurane. METHODS: Twelve patients were anesthetized with 70% N2O + 0.2% isoflurane (all concentrations are end-tidal). Following the end of surgery, the concentration of N2O was decreased in decrements of 10% while isoflurane was continued at 0.2%, and each new concentration of N2O was maintained for 15 min. This procedure was repeated until the patients first opened their eyes or squeezed the investigator's hand on command. RESULTS: N2O 70% + isoflurane 0.2% reduced the BIS to 68 +/- 9 (mean +/- SD). When the concentration of N2O was decreased toward awakening (which occurred at the N2O concentration of 36% +/- 8%), the BIS progressively increased until it reached 93 +/- 5 on awakening. CONCLUSION: The BIS reflects the level of hypnosis during N2O anesthesia supplemented with a low concentration of isoflurane.

Adult↗
PubMed2005

Nitrogen accumulation during closed circuit anesthesia depends on the type of surgery.

STUDY OBJECTIVE: The aim of this study is to test the hypothesis that the amount of nitrogen that accumulates within the closed breathing system would be greater during open abdominal surgery than during superficial surgery with small wounds. DESIGN: Prospective, comparative study. SETTING: Operating rooms of a university hospital. PATIENTS: Fourteen American Society of Anesthesiologists physical status I and II adult patients scheduled for abdominal surgery (n = 7) or tympanoplasty (n = 7). INTERVENTIONS: After induction of anesthesia and endotracheal intubation, the patients were denitrogenated for 30 minutes using 100% oxygen at a fresh gas flow of 10 L/min. The breathing system was then closed and patients were anesthetized using 60% xenon in oxygen, supplemented with epidural anesthesia in the abdominal surgery group and sevoflurane in the tympanoplasty group. MEASUREMENTS: Nitrogen concentration in the breathing system was determined by gas chromatography immediately before and 2 hours after the breathing system was closed. MAIN RESULTS: The median (range) increase in nitrogen concentration during the 2-hour period of closed circuit anesthesia was greater in the abdominal surgery patients than in the tympanoplasty patients (6.5% [4.0%-10.2%] vs 2.5% [1.4%-8.4%], P = 0.035, Mann-Whitney U test). CONCLUSIONS: The amount of nitrogen accumulation during closed circuit anesthesia is greater during open abdominal surgery than in superficial surgery such as tympanoplasty. We postulate that during open abdominal surgery, nitrogen in the ambient air enters the body across the peritoneum and then diffuses into the alveoli to be exhaled.

Abdomen↗
PubMed2004

Determination of right ventricular function by transesophageal echocardiography: impact of proximal right coronary artery stenosis.

STUDY OBJECTIVE: To investigate whether transesophageal echocardiography (TEE) can provide accurate information on right ventricular (RV) function in patients with right coronary artery (RCA) stenosis, given that a decrease in blood supply from the RCA may invalidate the use of single 2-D echocardiography imaging plane as a guide to RV function. DESIGN: Prospective, nonblinded study. SETTING: University hospital. PATIENTS: 30 adult patients undergoing elective cardiac or vascular procedures. INTERVENTIONS: Patients were classified into two groups according to the presence or absence of the proximal RCA (segment 1 or 2) stenosis. Group A patients had no obstructive lesions in the proximal RCA (n = 15). Group B patients had 75% or greater obstructive lesions in the proximal RCA (n = 15). MEASUREMENTS AND MAIN RESULTS: After induction of anesthesia, RV function was evaluated by both fast-response thermodilution pulmonary artery catheter and TEE. Transesophageal echocardiography-derived RV fractional area change (FAC) and tricuspid annular plane systolic excursion ratio (TAPSE ratio) were compared with thermodilution-derived RV ejection fraction (EF) using linear regression analysis. Transesophageal echocardiography-derived RV end-diastolic area (EDA) was compared with thermodilution-derived end-diastolic volume (EDV). Both methods showed a good correlation in RV, EDV, and EF in Group A, but no correlations in Group B. CONCLUSIONS: Transesophageal echocardiography does not provide reliable information on RVEF and EDV when proximal RCA stenosis is present.

Coronary Stenosis↗
PubMed2003

Core temperature monitoring with new ventilatory devices.

UNLABELLED: Widespread use of new airway devices, such as the laryngeal mask airway (LMA) and the cuffed oropharyngeal airway (COPA), preclude measuring core temperature in the distal esophagus. Therefore, we tested the hypothesis that core temperature measured with a thermocouple positioned on a LMA or COPA is sufficiently accurate and precise for clinical use. Temperatures were recorded from thermocouples positioned on the cuffs of LMAs or COPAs in 36 patients scheduled for prolonged orthopedic surgery or therapeutic hyperthermia for cancer. These temperatures, recorded at 15-min intervals, were compared with simultaneously obtained nasopharynx and tympanic membrane temperatures. Data were compared by linear regression and the bias calculated. Temperatures measured on the LMA correlated well with both nasopharyngeal (r(2) = 0.94) and tympanic membrane (r(2) = 0.94) temperatures. Temperatures measured on the COPA also correlated well with those on the nasopharynx (r(2) = 0.97) and tympanic membrane (r(2) = 0.96). The fraction of temperatures that differed from nasopharynx temperature by more than +/-0.5 degrees C was 8% with LMA and 11% with COPA; the fraction of temperatures that differed from tympanic temperature by more than +/-0.5 degrees C was 7% with LMA and 10% with COPA. These results suggest that body temperature measured from the cuffs of COPA or LMAs is sufficiently accurate for routine clinical use. IMPLICATIONS: Temperatures measured on airway devices correlated well with independent measurements of core body temperature. Thus, body temperature measured on the cuffs of airway devices is sufficiently accurate for routine use.

Adult↗
PubMed2002

Pollution of the medical air at a university hospital in the metropolitan Tokyo area.

STUDY OBJECTIVE: To investigate the quality of medical air in a hospital in the metropolitan area. DESIGN: Prospective study. SETTING: University hospital in the metropolitan Tokyo area. INTERVENTIONS: Medical air introduced into a bio-clean operating room was sampled. MEASUREMENTS: The concentrations of nitric monoxide (NO), nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), and carbon monoxide (CO) in the medical air were measured every 30 minutes for 15 days. MAIN RESULTS: The concentrations (mean +/- SD) of NO, NO(2), SO(2), and CO were 34.4 +/- 35.0 ppb (range 0-200 ppb), 7.7 +/- 5.5 ppb (0-29 ppb), 33.8 +/- 2.9 ppb (21-46 ppb), and 1.65 +/- 0.87 ppm (0.5-7.5 ppm), respectively. The concentrations of these gases peaked at rush hours within a day. CONCLUSIONS: In the metropolitan area, we occasionally provide our patients with medical air of poor quality.

Air Pollution, Indoor↗
PubMed2002

The minimum alveolar concentration of xenon in the elderly is sex-dependent.

BACKGROUND: The minimum alveolar concentration (MAC) of xenon in the elderly has not been determined. Moreover, because xenon inhibits the activity of the N-methyl-D-aspartate receptors, and because N-methyl-D-aspartate receptor antagonists such as ketamine and MK-801 exert sex-dependent actions, we hypothesized that the MAC of xenon would also be sex-dependent. METHODS: Forty-eight patients of both sexes (24 patients of each sex), who were aged 65 yr or older and were undergoing elective laparotomy, were anesthetized with inhalational induction of xenon. Those who demonstrated marked agitation received supplemental propofol intravenously. After tracheal intubation, the end-tidal concentration of xenon was maintained at 45 (women only), 50, 55, 60, 65, 70, or 75% (men only) for at least 15 min before skin incision. These concentrations were randomly allocated to four patients of each sex. Each patient was monitored for the presence or absence of any purposeful bodily movement for 1 min following skin incision. The MAC of xenon was calculated separately for men and women using logistic regression analysis. RESULTS: The MAC of xenon was 69.3% (95% CI, 63.0-75.6%) for men and 51.1% (44.6-57.6%) for women. The two 95% confidence intervals did not overlap, indicating a statistically significant difference (P < 0.05). CONCLUSIONS: The MAC of xenon in the elderly is higher in men than in women.

Aged↗