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Biomedical subjects

Kahoru Nishina

Publications and source records attributed to Kahoru Nishina.

10 recordsLinked to original sources
PubMed2004

Efficacy of partial liquid ventilation in improving acute lung injury induced by intratracheal acidified infant formula: determination of optimal dose and positive end-expiratory pressure level.

OBJECTIVES: Partial liquid ventilation with fluorocarbon was successfully used for acute lung injury induced by oleic acid or lung lavage. Positive end-expiratory pressure (PEEP) during partial liquid ventilation enhances the efficacy of fluorocarbon. The aim of the current study was to assess whether partial liquid ventilation can repair lung damage induced by intratracheal acidified infant formula and to determine the optimal fluorocarbon dose and PEEP level. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SETTING AND SUBJECTS: Seventy-six male anesthetized rabbits. INTERVENTIONS: For study 1, acute lung injury was induced by intratracheal acidified infant formula in four groups. Next, three groups received 10, 15, or 20 mL/kg fluorocarbon, and the fourth group was conventionally gas ventilated. For study 2, acute lung injury was induced in five groups. One group was gas ventilated at a PEEP of 5 cm H2O, whereas the other four groups received fluorocarbon (15 mL/kg) and were assigned to one of four PEEP levels (5, 7.5, 10, or 12.5 cm H2O). The lungs were ventilated with 100% oxygen for 4 hrs after acute lung injury. MEASUREMENTS AND MAIN RESULTS: In study 1, fluorocarbon at doses of 15 and 20 mL/kg attenuated lung leukosequestration and edema and superoxide production of neutrophils, resulting in similar improvements in oxygenation, lung mechanics, and pathologic changes. The highest fluorocarbon dose caused mortality from pneumothorax. In study 2, the combination of PEEP with partial liquid ventilation improved gas exchange, lung compliance, pulmonary edema, and histologically observed damage. The beneficial effects of PEEP at 10 and 12.5 cm H2O were similar. Adverse side effects of 12.5 cm H2O PEEP included pneumothorax and hemodynamic instability. CONCLUSIONS: The combination of fluorocarbon and PEEP improved the physiologic, biochemical, and histologic lung injury induced by acidified infant formula. The beneficial effects of partial liquid ventilation are due, in part, to inhibition of pulmonary neutrophil accumulation and activation with fluorocarbon. The optimal fluorocarbon dose and PEEP level in our model were 15 mL/kg and 10 cm H2O, respectively.

Analysis of Variance↗
PubMed2003

The effects of enflurane, isoflurane, and intravenous anesthetics on rat diaphragmatic function and fatigability.

UNLABELLED: We examined the effect of isoflurane, enflurane, midazolam, ketamine, propofol, and thiopental on diaphragmatic functions under unfatigued and fatigued conditions in 228 rat isolated muscle strips. Diaphragmatic twitch characteristics and tetanic contractions were measured before and after muscle fatigue, which was induced by repetitive tetanic contraction with or without exposure to one of the anesthetics at clinically relevant plasma concentrations, and at 10 and 100 times this concentration, or at 1, 2, and 3 minimum alveolar anesthetic concentration (MAC). Isoflurane, midazolam, ketamine, propofol, and thiopental did not induce a direct inotropic or lusitropic effect under unfatigued and fatigued conditions. Enflurane did not change contraction or relaxation in fresh isolated diaphragm, but enflurane at 2-3 MAC enhanced diaphragmatic fatigability itself and fatigue-induced impairment of twitch characteristics and tetanic tensions. These effects were greater at 3 MAC than at 2 MAC. Our findings suggest that the reduction of diaphragm function previously reported in in vivo experiments using propofol, midazolam, and isoflurane is not related to a direct effect on intrinsic diaphragmatic contractility. Our results also indicate that large concentrations of enflurane may impair the diaphragmatic function at sites other than excitation-contraction coupling. IMPLICATIONS: Enflurane did not change contraction or relaxation in fresh isolated rat diaphragm, but enhanced diaphragmatic fatigability itself and fatigue-induced impairment of twitch characteristics and tetanic tensions. Isoflurane, midazolam, ketamine, propofol, and thiopental had no direct effects on diaphragmatic functions under unfatigued and fatigued conditions. Isoflurane and these i.v. anesthetics may be advantageous over enflurane to anesthetize and/or sedate patients who are predisposed to diaphragmatic fatigue.

Anesthetics, Inhalation↗
PubMed2003

ONO-1714, a nitric oxide synthase inhibitor, attenuates endotoxin-induced acute lung injury in rabbits.

UNLABELLED: Overproduction of nitric oxide by inducible nitric oxide synthase (iNOS) expressed in the lung is thought to play a crucial role in the pathogenesis of endotoxin-induced acute lung injury (ALI). In this two-part study, we determined whether ONO-1714, a new selective iNOS inhibitor, attenuates endotoxin-induced ALI in rabbits. For Part I of the study, a control group received IV saline and ALI was induced by IV infusion of endotoxin 5 mg/kg over 30 min in 4 groups. Three groups received either 0.1, 0.03, or 0.01 mg/kg of ONO-1714 10 min before the start of endotoxin and the fourth group received saline. For Part II of the study, ALI was induced by endotoxin infusion in all 6 groups. One group was treated with saline. The other 5 groups received ONO-1714 0.1 mg/kg at various timings (10 min before or 1, 2, 3, or 4 h after ALI induction). The lungs were mechanically ventilated with 40% oxygen for 6 h after induction of ALI. In Part I, pretreatment with 0.1 mg/kg ONO-1714 mitigated endotoxin-induced ALI. In Part II, early posttreatment (within 2 h after the insult) with ONO-1714 was as effective as pretreatment in improving oxygenation, lung mechanics, lung leukosequestration, pulmonary edema, and histological change. However, lung damage was not improved in rabbits receiving the drug 3 or 4 h after endotoxin. These data suggest that the current study is a basis for future clinical trials to elucidate whether ONO-1714 can be a promising therapeutic approach in patients with acute respiratory distress syndrome induced by endotoxin/sepsis. IMPLICATIONS: An excess of nitric oxide is thought to play a crucial role in the pathogenesis of acute organ injury in endotoxemia. Early posttreatment with ONO-1714, a nitric oxide synthase inhibitor, attenuated physiological, biochemical, and pathological changes in endotoxin-induced acute lung injury in rabbits.

Airway Resistance↗
PubMed2002

Accuracy of visual estimation of body height and weight in supine paediatric patients.

BACKGROUND: When it is impossible to measure the weight and height of paediatric patients, these are usually estimated. We undertook this study to see how accurate these estimates are in practice. METHODS: Five observers estimated body height and weight, and subsequently calculated body surface area, in 48 paediatric inpatients who were lying on surgical ward trolleys. RESULTS: Regression analysis of the data revealed that good correlations existed between estimated and actual body size in all the investigators. However, we found large percentage errors in estimation for infants and younger children with small physical size, and a variation in scatter distribution of estimation errors among the five investigators. CONCLUSIONS: These findings suggest the necessity to titrate drug doses for administration in this small paediatric population.

Adjuvants, Anesthesia↗
PubMed2002

The effects of intravenous anesthetics and lidocaine on proliferation of cultured type II pneumocytes and lung fibroblasts.

UNLABELLED: Type II pneumocytes synthesize surfactant and differentiate into type I pneumocytes to maintain the epithelium (1). Alveolar type II cell proliferation is required for reepithelization after acute lung injury (ALI) and is thought to minimize the subsequent fibrotic response (1). Keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF) are among the most potent mitogen for type II epithelial cells, but not for fibroblasts in the lung (1). These growth factors attenuate several experimental ALI models by promoting epithelial repair (2,3). Thus, KGF and HGF may be a promising therapeutic approach to ALI. Critically ill patients with ALI often receive IV anesthetics or sedatives to facilitate mechanical ventilation. Furthermore, these patients sometimes undergo bronchoscopy under local anesthesia to obtain bronchoalveolar lavage fluid or to remove respiratory secretions. Several IV and local anesthetics inhibit proliferation of various cells including epithelium (4,5). If these anesthetics impede proliferation of type II pneumocytes, this suppressive effect may be a disadvantage for alveolar reepithelization in the course of recovery from ALI. In this study, we examined the effects of midazolam, propofol, ketamine, thiopental, and lidocaine on proliferation of type II alveolar epithelial cells using in vitro culture system. Because fibroblast proliferation is a key event in late phase of ALI, inhibition of this fibroproliferation is probably beneficial. Thus, we further determined whether these anesthetics could regulate proliferation of lung fibroblasts. In the current study, rolipram was used as a positive control. In our previous preliminary experiment, we found that rolipram, a phosphodiesterase inhibitor type IV, augments spontaneous or KGF-/HGF-promoted type II cell proliferation (6). IMPLICATIONS: Midazolam, ketamine, thiopental, propofol, or lidocaine did not inhibit proliferation of cultured rat type II pneumocytes. Our findings suggest that these anesthetics do not impede alveolar reepithelization after acute lung injury.

Anesthetics, Dissociative↗
PubMed2002

The efficacy of lafutidine in improving preoperative gastric fluid property: a comparison with ranitidine and rabeprazole.

IMPLICATIONS: Acid aspiration syndrome remains a potentially critical perioperative complication. We compared lafutidine, ranitidine, and rabeprazole for reduction of preoperative gastric fluid acidity and volume in elective surgery and found that these variables were minimized with a single morning dose of lafutidine 20 mg compared with ranitidine or rabeprazole. Preoperative oral lafutidine may be an alternative to ranitidine as a prophylaxis against aspiration pneumonia.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2002

Efficacy of clonidine for prevention of perioperative myocardial ischemia: a critical appraisal and meta-analysis of the literature.

BACKGROUND: There is a belief that clonidine may be effective in reducing perioperative myocardial ischemic events, although the results of several trials are conflicting. The aim of the current study was to provide a systematic review of randomized controlled trials that tested the efficacy of clonidine in this regard. METHODS: Data was collected from a MEDLINE search of English-language studies published from 1980 to 1999 and a manual search of bibliographies from retrieved articles. A total of 28 studies were assessed. According to the selection criteria (study design, population, intervention, and outcome) and a quality scoring system, seven studies were finally included in the meta-analysis. After homogeneity was established by Q value, the data were then combined using the fixed-effects model. The pooled odds ratio was calculated. A subgroup analysis based on the types of surgery and administration route was also performed to qualify the results. The results were expressed as odds ratio and 95% confidence interval. RESULTS: Heterogeneity of outcome data was negative in the trials. The pooled odds ratio was 0.49 (95% confidence interval 0.34-0.71). In the subgroup analysis, clonidine reduced the incidence of myocardial ischemia in patients undergoing cardiac and noncardiac surgery. Rates of bradycardia were similar in clonidine and placebo groups. CONCLUSION: The meta-analysis suggests that perioperative clonidine reduces cardiac ischemic episodes in patients with known, or at risk of, coronary arterial disease without increasing the incidence of bradycardia. Therefore, these findings strongly justify planning and execution of a definitive study seeking the benefits of clonidine.

Adrenergic alpha-Agonists↗
PubMed2002

Effects of ondansetron, granisetron, ramosetron, and azasetron on human neutrophil functions.

Neutrophil functions play an important role in the antibacterial or antitumor host defense system. Ondansetron, granisetron, ramosetron, and azasetron are often used in gynecological patients as a prophylaxis against postoperative emesis or chemotherapy-induced emesis. In this study, using an ex vivo system, we have shown that these antiemetics at clinically relevant concentrations had no effect on superoxide (O(-)(2)) and hydrogen peroxide (H(2)O(2)) production of neutrophils, although high doses of these drugs significantly inhibited it to a similar degree. The drugs failed to impair chemotaxis or phagocytosis and to scavenge O(-)(2) or H(2)O(2) generated by an acellular system. Inhibition of the reactive oxygen species production may be due to attenuation of calcium elevation in neutrophils with these antiemetics. Our findings suggest that we are able to use these antiemetics in gynecological patients with cancer or those undergoing surgery without great caution.

Antiemetics↗