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Background: Fentanyl produces a reduction in the minimum alveolar concentration (MAC) of isoflurane and desflurane needed to blockade adrenergic response (BAR) to surgical incision in 50% of patients (MAC-BAR). MAC-BAR of sevoflurane and the reduction in MAC-BAR of sevoflurane by fentanyl have not been described previously. The purpose of this study was to determine the MAC and MAC-BAR reduction of sevoflurane by fentanyl with and without nitrous oxide (N2O)., Methods: Two hundred twenty-six patients were randomly assigned to one of two groups: a sevoflurane group and a sevoflurane/N2O group. Patients in each group were randomly assigned to one of five different fentanyl concentration subgroups. Patients were anesthetized with sevoflurane and fentanyl in the sevoflurane group and with sevoflurane, fentanyl, and N2O (66 vol%) in the sevoflurane/N2O group. Somatic and sympathetic responses to surgical incision were observed for MAC and MAC-BAR assessment at predetermined concentrations of sevoflurane., Results: Fentanyl produced an initial steep reduction in the MAC and MAC-BAR of sevoflurane, with 3 ng/ml resulting in a 61% reduction in MAC and an 83% reduction in MAC-BAR. A ceiling effect was observed for MAC and MAC-BAR, with 6 ng/ml fentanyl providing only an additional 13% and 9% reduction in MAC and MAC-BAR, respectively. In the presence of 66 vol% N2O, MAC and MAC-BAR of sevoflurane were reduced with increasing concentrations of fentanyL A ceiling effect was not observed for reduction in MAC and MAC-BAR in the presence of N2O., Conclusions: MAC and MAC-BAR decreased similarly with increasing concentrations of fentanyl in plasma, showing an initial steep reduction followed by a ceiling effect. In the presence of N2O, MAC and MAC-BAR decreased similarly but did not exhibit a ceiling effect.

Proteins of the membrane-associated guanylate kinase family play an important role in the anchoring and clustering of neurotransmitter receptors in the postsynaptic density (PSD) at many central synapses. However, relatively little is known about how these multifunctional scaffold proteins might provide a privileged site for activity- and cell type-dependent specification of the postsynaptic signaling machinery. Rho signaling pathway has classically been implicated in mechanisms of axonal outgrowth, dendrogenesis, and cell migration during neural development, but its contribution remains unclear at the synapses in the mature CNS. Here, we present evidence that Citron, a Rho-effector in the brain, is enriched in the PSD fraction and interacts with PSD-95/synapse-associated protein (SAP)-90 both in vivo and in vitro. Citron colocalization with PSD-95 occurred, not exclusively but certainly, at glutamatergic synapses in a limited set of neurons, such as the thalamic excitatory neurons; Citron expression, however, could not be detected in the principal neurons of the hippocampus and the cerebellum in the adult mouse brain. In a heterologous system, Citron was shown to form a heteromeric complex not only with PSD-95 but also with NMDA receptors. Thus, Citron-PSD-95/SAP-90 interaction may provide a region- and cell type-specific link between the Rho signaling cascade and the synaptic NMDA receptor complex.

Purpose: Sevoflurane metabolism results in the production of inorganic fluoride, which is known to be nephrotoxic. Since marked changes in body temperature and hemodynamics in cardiac surgery affect sevoflurane metabolism, plasma inorganic fluoride concentrations may differ in this situation compared with other types of surgery. We therefore measured plasma inorganic fluoride concentrations during and after sevoflurane anesthesia in patients undergoing cardiac surgery., Methods: Sixteen patients undergoing coronary artery bypass grafting or valve replacement were premedicated with 5-10 mg midazolam and 0.5 mg scopolamine injected intramuscularly. Anesthesia was induced with 5-10 mg midazolam, 0.5-1 mg fentanyl, and 0.12-0.15 mg.kg(-1) vecuronium. Following tracheal intubation, anesthesia was maintained with oxygen, sevoflurane, and fentanyl. At the onset of cardiopulmonary bypass (CPB), sevoflurane was discontinued, and additional fentanyl, midazolam, and pancuronium were administered. Plasma inorganic fluoride concentrations were measured before anesthesia, immediately before and after CPB, and at 0, 2, 6, 12, 24, and 48 h after anesthesia., Results: The individual maximum plasma inorganic fluoride concentration was 19.2 +/- 7.2 micromol.l(-1) (mean +/- SD; range, 9.2-36.7). The mean plasma inorganic fluoride concentrations increased during anesthesia, but the rate of increase decreased after the initiation of CPB. Concentrations peaked at 2 h after anesthesia and decreased thereafter. The concentrations in three cases continued to increase 2 h after anesthesia., Conclusion: The plasma inorganic fluoride concentrations observed in patients undergoing cardiac surgery were below nephrotoxic levels. However, the decrease in mean fluoride concentration after anesthesia was slower than that in the previous study in general surgical patients.

We compared the distance between the upper central incisors and the laryngoscope blade with the four different types of laryngoscope blade (McCoy, Macintosh, Miller, Belscope). Twenty-three patients scheduled for general anesthesia were studied. The tooth-blade distance was measured when optimum visibility of the glottis was obtained. The visibility was determined according to the Cormack and Lehane grading. The distance with the McCoy and the Belscope was greater than that with the Macintosh or the Miller. The visibility grade was significantly worse with the Macintosh than with the other types of laryngoscope. The results indicate that the McCoy and the Belscope provide less incidence of upper dental injuries and greater visibility than either with the Macintosh or the Miller. Furthermore, the force applied to the handle is thought to be smaller with the McCoy than with the Belscope.

Effectiveness in visualization of the vocal cord during orotracheal intubation with McCoy (McC) compared with Macintosh (Min) and Miller (Mil) blades were investigated. After an institutional review board approval, 117 patients for elective surgery under general anesthesia requiring tracheal intubation were investigated. Five board certified anesthesiologists tried to visualize the vocal cord of a patient three times with the three different types of laryngoscope. Total of 351 intubation attempts were studied. The view obtained at laryngoscopy with each of the three blades was recorded as follows. Grade 1. If most of the glottis is visible. Grade 2. If only the posterior extremity of the glottis is visible. Grade 3. If no part of the glottis can be seen. Grade 4. If not even the epiglottis can be exposed. Eight-two Grade 1 views were obtained with McC, 72 with Mil and 47 with Min, respectively. Thirty-three Grade 2 views were obtained with McC, 36 with Min and 24 with Mil. Two Grade 3 views with McC, 34 with Min and 14 with Mil were obtained. Seven Grade 4 views were obtained with Mil. The grades of laryngeal visualization with McC were significantly lower than those with Min and Mil.

During mitosis, a ring containing actin and myosin appears beneath the equatorial surface of animal cells. This ring then contracts, forms a cleavage furrow and divides the cell, a step known as cytokinesis. The two daughter cells often remain connected by an intercellular bridge which contains a refringent structure known as the midbody. How the appearance of this ring is regulated is unclear, although the small GTPase Rho, which controls the formation of actin structures, is known to be essential. Protein kinases are also thought to participate in cytokinesis. We now show that a splice variant of a Rho target protein, named citron, contains a protein kinase domain that is related to the Rho-associated kinases ROCK14 and ROK, which regulate myosin-based contractility. Citron kinase localizes to the cleavage furrow and midbody of HeLa cells; Rho is also localized in the midbody. We find that overexpression of citron mutants results in the production of multinucleate cells and that a kinase-active mutant causes abnormal contraction during cytokinesis. We propose that citron kinase regulates cytokinesis at a step after Rho in the contractile process.

A critical role for the small GTPase Rho and one of its targets, p160ROCK (a Rho-associated coiled coil-forming protein kinase), in neurite remodeling was examined in neuroblastoma N1E-115 cells. Using wild-type and a dominant-negative form of p160ROCK and a p160ROCK-specific inhibitor, Y-27632, we show here that p160ROCK activation is necessary and sufficient for the agonist-induced neurite retraction and cell rounding. The neurite retraction was accompanied by elevated phosphorylation of myosin light chain and the disassembly of the intermediate filaments and microtubules. Y-27632 blocked both neurite retraction and the elevation of myosin light chain phosphorylation in a similar concentration-dependent manner. On the other hand, suppression of p160ROCK activity by expression of a dominant-negative form of p160ROCK induced neurites in the presence of serum by inducing the reassembly of the intermediate filaments and microtubules. The neurite outgrowth by the p160ROCK inhibition was blocked by coexpression of dominant-negative forms of Cdc42 and Rac, indicating that p160ROCK constitutively and negatively regulates neurite formation at least in part by inhibiting activation of Cdc42 and Rac. The assembly of microtubules and intermediate filaments to form extended processes by inhibitors of the Rho-ROCK pathway was also observed in Swiss 3T3 cells. These results indicate that Rho/ROCK-dependent tonic inhibition of cell process extension is exerted via activation of the actomysin-based contractility, in conjunction with a suppression of assembly of intermediate filaments and microtubules in many cell types including, but not exclusive to, neuronal cells.

Synaptic transmission is a key signaling event, whereby an action potential-induced release of chemical neurotransmitters again generates a positive or negative electrical activity via opening of postsynaptic channels. Thereafter, information spreads through space, from the postsynaptic membranes to the dendrites, to the soma, to the nucleus, to the presynaptic terminals and, in some cases, back to the originally stimulated synapses. Furthermore, information is also often converted in time, either by shifting the phase of electrical activity during the integration of EPSPs and IPSPs into the generation of an action potential, or by triggering a long-lasting cascade of enzymatic or protein-protein interaction-mediated events in the cytoplasm and in the nucleus. Recent studies of the signaling from the synapse to the nucleus now allow us to consider how various patterns of synaptic activity could couple with activation of specific nuclear transcription factors and thus regulate neuronal gene expression. The critical importance of Ca(2+)-dependent signaling processes in such regulatory events will be discussed below.

Background: Sevoflurane anesthesia is usually performed with fresh gas flow rates greater than 2 l/min due to the toxicity of compound A in rats and limited clinical experience with sevoflurane in low-flow systems. However, to reduce costs, it would be useful to identify ways to reduce compound A concentrations in low-flow sevoflurane anesthesia. This goal of this study was to determine if compound A concentrations can be reduced by using soda lime with water added., Methods: Low-flow sevoflurane anesthesia (fresh gas flow of 1 l/min) was performed in 37 patients using soda lime with water added (perhydrated soda lime) or standard soda lime as the carbon dioxide (CO2) absorbent. The soda lime was not changed between patients, but rather was used until CO2 rebreathing occurred. The perhydrated soda lime was prepared by spraying 100 ml distilled water onto 1 kg fresh soda lime, and water was added only when a new bag of soda lime was placed into the canister. Compound A concentrations in the circle system, soda lime temperatures, inspired and end-tidal CO2 and end-tidal sevoflurane concentrations, and CO2 elimination by the patient were measured during anesthesia., Results: Compound A concentrations were significantly lower for the perhydrated soda lime (1.9 +/- 1.8 ppm; means +/- SD) than for the standard soda lime (13.9 +/- 8.2 ppm). No differences were seen between the two types of soda lime with regard to the temperature of the soda lime, end-tidal sevoflurane concentrations, or CO2 elimination. Compound A concentration decreased with the total time of soda lime use for both types of soda lime. The CO2 absorption capacity was significantly less for perhydrated soda lime than for standard soda lime., Conclusions: Compound A concentrations in the circuit can be reduced by using soda lime with water added. The CO2 absorption capacity of the soda lime is reduced by adding water to it, but this should not be clinically significant.

Stress responses during laryngoscopy were compared among the situations using three different laryngoscopes, Macintosh (curved standard blade), Miller (straight blade), or McCoy (levering). Blood pressure, heart rate (in 58 patients) and plasma concentration of catecholamines (in 29 patients) were measured before, during and after laryngoscopy without tracheal intubation. Systolic blood pressure after laryngoscopy was significantly higher in the Miller group than in other two groups. Plasma epinephrine concentrations after laryngoscopy in the McCoy group were lower than other two groups. Heart rate and plasma norepinephrine concentration were not different among the three groups. These results suggest that the stress response during laryngoscopy without intubation is the biggest in using the Miller laryngoscope and the smallest in using the McCoy laryngoscope.

Twenty-nine inexperienced medical students tried to intubate endotracheal tubes using both levering laryngoscope (McCoy laryngoscope) and Macintosh laryngoscope in adult mannikin the Cormack and Lehane Grade 2. The number of successful intubations by McCoy type was close to those by Macintosh type. Improvement in time necessary from insertion of the laryngoscope to confirmation of placement of the endotracheal tube McCoy type was also close to that by Macintosh type. But the grade of handling difficulty of McCoy type was significantly higher than that of Macintosh type, because Macintosh type was simpler to handle than McCoy type. It was suggested that Macintosh laryngoscope was more useful than McCoy laryngoscope for teaching of inexperienced medical students.

Patients with suppressed systemic circulation under general anesthesia received a 20-minute continuous infusion of toborinone at a rate of 5, 10, or 15 micrograms.kg-1.min-1, and the efficacy and safety of the drug were evaluated. Toborinone increased cardiac index (CI) and stroke volume index (SVI) dose-dependently, with significant increases at 10 and 15 micrograms.kg-1.min-1. An increase in CI was observed from 10 minutes after the start of infusion, with a return to the baseline value at 20-30 minutes after the completion of infusion. Toborinone did not affect heart rate at any dose tested, but the drug tended to decrease mean pulmonary arterial pressure, pulmonary capillary wedge pressure, and right atrial pressure. Mean arterial blood pressure tended to decrease after the start of infusion at all doses tested, and was significantly decreased at 20 minutes after the start of infusion at 10 and 15 micrograms.kg-1.min-1. Systemic vascular resistance and pulmonary vascular resistance decreased at all doses tested. T-wave amplitude on electrocardiaogram (ECG) and oxygen partial pressure in arterial blood decreased at 10 and 15 micrograms.kg-1.min-1. Toborinone increases cardiac output and decreases pre-load and after-load with no effects on heart rate, and, therefore, is thought to be a positive inotropic agent useful in the treatment of circulatory insufficiency. Due care should be exercised to monitor blood pressure, ECG, and arterial blood gas parameters of the patients. The effects of toborinone need to be further investigated in patients with complicated cardiac diseases under general anesthesia and in patients with circulatory insufficiency after surgery, including patients following extracorporeal circulation.

Ca2+ is an important signal-transduction molecule that plays a role in many intracellular signaling pathways. Recent advances have indicated that in neurons, Ca2+-controlled signaling mechanisms cooperate in order to discriminate amongst incoming cellular inputs. Ca2+-dependent transcriptional events can thereby be made selectively responsive to bursts of synaptic activity of specific intensity or duration.

Background: The safety of low-flow sevoflurane anesthesia, during which CF2=C(CF3)-O-CH2F (compound A) is formed by sevoflurane degradation, in humans has been questioned because compound A is nephrotoxic in rats. Several reports have evaluated renal function after closed-circuit or low-flow sevoflurane anesthesia, using blood urea nitrogen (BUN) and serum creatinine as markers. However, these are not the more sensitive tests for detecting renal damage. This study assessed the effects of low-flow sevoflurane anesthesia on renal function using not only BUN and serum creatinine but also creatinine clearance and urinary excretion of kidney-specific enzymes, and it compared these values with those obtained in high-flow sevoflurane anesthesia and low-flow isoflurane anesthesia., Methods: Forty-eight patients with gastric cancer undergoing gastrectomy were studied. Patients were randomized to receive sevoflurane anesthesia with fresh gas flow of 1 l/min (low-flow sevoflurane group; n = 16) or 6-10 l/min (high-flow sevoflurane group; n = 16) or isoflurane anesthesia with a fresh gas flow of 1 l/min (low-flow isoflurane group; n = 16). In all groups, the carrier gas was oxygen/nitrous oxide in the ratio adjusted to ensure a fractional concentration of oxygen in inspired gas (FiO2) of more than 0.3. Fresh Baralyme was used in the low-flow sevoflurane and low-flow isoflurane groups. Glass balls were used instead in the high-flow sevoflurane group, with the fresh gas flow rate adjusted to eliminate rebreathing. The compound A concentration was measured by gas chromatography. Gas samples taken from the inspiratory limb of the circle system at 1-h intervals were analyzed. Blood samples were obtained before and on days 1, 2, and 3 after anesthesia to measure BUN and serum creatinine. Twenty-four-hour urine samples were collected before anesthesia and for each 24-h period from 0 to 72 h after anesthesia to measure creatinine, N-acetyl-beta-D-glucosaminidase, and alanine aminopeptidase., Results: The average inspired concentration of compound A was 20 +/- 7.8 ppm (mean +/- SD), and the average duration of exposure to this concentration was 6.11 +/- 1.77 h in the low-flow sevoflurane group. Postanesthesia BUN and serum creatinine concentrations decreased, creatinine clearance increased, and urinary N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase excretion increased in all groups compared with preanesthesia values, but there were no significant differences between the low-flow sevoflurane, high-flow sevoflurane, and low-flow isoflurane groups for any renal function parameter at any time after anesthesia., Conclusions: The only difference between the low-flow and high-flow sevoflurane groups was compound A formation, and postanesthesia laboratory data showed no significant effects of compound A formation during sevoflurane anesthesia on renal function. No significant effects on renal function were observed in either the low-flow or high-flow sevoflurane groups compared with the low-flow isoflurane group.

Dendritic arbors are critical for the information processing capability of central neurons, but quantitative analysis of their membrane properties has been hampered by their geometrical complexity. Here, we have focused on an important source of Ca2+ entry in dendrites, the voltage-gated Ca2+ channels, by applying the whole-cell voltage-clamp technique to isolated dendritic segments ("dendrosomes") from rat hippocampal neurons. We found that low voltage-activated T-type Ca2+ channels provide a significantly larger fraction of the Ca2+ influx in dendrites than their counterparts in cell bodies. Surprisingly, 60%-70% of the high voltage-activated Ca2+ current in dendrosomes was N and P/Q type, and these channels were susceptible to neurotransmitter inhibition, suggesting a novel physiological role for G protein-regulated Ca2+ channel modulation in controlling dendritic excitability and Ca2+ signaling.

We experienced the anesthetic management of a patient with severe anemia as low as 1.8 g.dl-1 of hemoglobin and 6.5 per cent of hematocrit before surgery. His blood had been determined as type B, anti-Jra antibody positive and the proper blood was unavailable. We gave mainly colloid fluids and partially blood products of different blood groups to maintain the circulating volume with monitoring central venous pressure peri-operatively. The operation finished relatively uneventfully and the patient was transferred to the common ward from the intensive care unit on the fifth postoperative day. We conclude that maintaining the patient's circulating volume to avoid shock should be given priority in a case of severe anemia.

The movement of cervical spine during orotracheal intubation was compared using the McCoy, Macintosh or Miller laryngoscope blade. Twenty ASA 1-2 patients requiring tracheal intubation were studied. Following induction of anesthesia and obtaining muscle relaxation, the cross-table lateral X-ray was taken before and during laryngoscopy using three types of laryngoscopes. Degree of cervical spine movement was evaluated by measuring the distance between the spinous processes of C1 and the occiput, and the amount of displacement of C1 and C5 against C3 by tracing on each films. The results indicated that delta C1-occiput was larger and delta C1 + C5 smaller with the McCoy laryngoscope compared with the others. The use of the McCoy laryngoscope results in less cervical spine movement during laryngoscopy and therefore should be of particular benefit in the presence of cervical spine instability as well as in the normal patients.

While changes in gene expression are critical for many brain functions, including long-term memory, little is known about the cellular processes that mediate stimulus-transcription coupling at central synapses. In studying the signaling pathways by which synaptic inputs control the phosphorylation state of cyclic AMP-responsive element binding protein (CREB) and determine expression of CRE-regulated genes, we found two important Ca2+/calmodulin (CaM)-regulated mechanisms in hippocampal neurons: a CaM kinase cascade involving nuclear CaMKIV and a calcineurin-dependent regulation of nuclear protein phosphatase 1 activity. Prolongation of the synaptic input on the time scale of minutes, in part by an activity-induced inactivation of calcineurin, greatly extends the period over which phospho-CREB levels are elevated, thus affecting induction of downstream genes.

Platelet-activating factor (PAF) receptor and somatostatin receptor (SSTR4) were cloned, and their primary structures were identified. They are both highly expressed in the rat hippocampus. When expressed in Chinese hamster ovary cells, these receptors activated mitogen-activated protein (MAP) kinase cascade and phospholipase A2. Arachidonic acid or its derivatives, thus produced by the activation of these receptors may play some roles in synaptic transmission and synaptic plasticity.

Phosphorylation of the transcription factor CREB is thought to be important in processes underlying long-term memory. It is unclear whether CREB phosphorylation can carry information about the sign of changes in synaptic strength, whether CREB pathways are equally activated in neurons receiving or providing synaptic input, or how synapse-to-nucleus communication is mediated. We found that Ca(2+)-dependent nuclear CREB phosphorylation was rapidly evoked by synaptic stimuli including, but not limited to, those that induced potentiation and depression of synaptic strength. In striking contrast, high frequency action potential firing alone failed to trigger CREB phosphorylation. Activation of a submembranous Ca2+ sensor, just beneath sites of Ca2+ entry, appears critical for triggering nuclear CREB phosphorylation via calmodulin and a Ca2+/calmodulin-dependent protein kinase.

The safety of low-flow sevoflurane anesthesia, which produces higher concentrations of toxic compounds, has been questioned. One hundred surgical patients received sevoflurane or isoflurane anesthesia at a total flow rate of 1 L/min. End-tidal CO2 concentrations and inspired and end-tidal anesthetic concentrations were monitored during anesthesia. Pre- and postanesthetic clinical laboratory studies were performed in both groups, and no significant differences were found between groups. In the sevoflurane group, the concentrations of degradation products in the circuit were measured by gas chromatography and the temperature of the CO2 absorbent was also measured. Two degradation products were detected: CF2 = C(CF3-O-CH2F (Compound A) and CH3OCF2CH(CF3)OCH2F (Compound B). The highest measured mean concentration of Compound A was 24.6 +/- 7.2 (13.6-41.3) ppm, and that of Compound B (detected in 12 patients) was 1.5 ppm. In both groups, total bilirubin, direct bilirubin, aspartate aminotransferase, and alanine aminotransferase were increased postoperatively. There was no difference between groups. Low concentrations of Compound A were present in low-flow sevoflurane anesthesia, but no significant differences in clinical laboratory values were observed between low-flow sevoflurane and isoflurane anesthesia.

The guinea-pig leukotriene A4 hydrolase (LTA4H)-encoding cDNA was isolated from a guinea-pig lung cDNA library by cross-hybridization using a human probe. The deduced amino acid (aa) sequence consists of 611 aa (68 756 Da) and contains all twelve internal peptide and N-terminal sequences determined from the purified enzyme from guinea-pig intestine. The aa identity of the guinea-pig enzyme with its human, mouse and rat counterparts was 92.9, 90.5 and 90.4%, respectively. The previously characterized zinc-binding motif and a putative active site were highly conserved, supporting the aminopeptidase activity described for this enzyme. RNA blot analysis demonstrated ubiquitous expression of the LTA4H mRNA.

We describe the management of a 35-year-old female with microcephaly, cerebral atrophy especially in frontal lobes, dwarfism and severe mental retardation. The patient underwent open reduction of fracture of the humerus neck suffered from traffic accident. Authors could not find any article on the anesthetic management of microcephaly but could locate some about mentally retarded patients claiming the difficulty in anesthetic induction as well as emergence and frequent incidence of convulsions. We anesthetized the patient with modified NLA with nitrous oxide-oxygen and interestingly very small doses of fentanyl (1.7 micrograms.kg-1) were required. The anesthetic and surgical courses were uneventful. The patient emerged immediately with intravenously administered naloxone and flumazenil with no excitement nor convulsion. We conclude that fentanyl is the drug of choice for mentally retarded patient with microcephaly and smaller doses per kg.weight are sufficient for orthopedic surgery.

Platelet-activating factor and somatostatin receptors, two G protein-coupled receptors expressed in the rat hippocampus, were analyzed for the downstream signaling pathways in Chinese hamster ovary cells stably expressing each receptor. Ligand stimulation to each CHO cell line induced (1) inhibition of forskolin-induced accumulation of cAMP, (2) arachidonate release, and (3) activation of mitogen-activated protein kinase and MAP kinase kinase. In contrast, inositol phosphate breakdown was seen only in the PAF-stimulated CHO cells. The induction of these signals accompanied no detectable Ras activation. Suppression of the signals by pertussis toxin was almost complete for the somatostatin receptor but partial for the PAF receptor, suggesting that the somatostatin receptor couples only with PTX-sensitive G protein, while the PAF receptor couples with both PTX-sensitive and -insensitive G proteins. A model of G protein-mediated signaling pathways was proposed in which the signals from Gi and those from Gq converge at MAP kinase kinase and lead to arachidonate release. The present system using CHO cells is useful for analyzing signaling pathways from G proteins to MAP kinase kinase and will thereby provide clues for understanding the mechanisms underlying the physiological and pathological events mediated by PAF, somatostatin, and other G protein-coupled receptors in the central nervous system and other tissues.

Plasma inorganic fluoride (F-) concentrations in long-duration, low-flow sevoflurane anesthesia were studied to assess effects on renal and hepatic function. The intracircuit concentration of degradation product generated by reaction between sevoflurane and CO2 absorbant was also determined. Ten patients undergoing prolonged surgery of 10 h or longer received sevoflurane anesthesia at 1 L/min. Plasma F- concentration was measured and clinical laboratory tests were performed. Intracircuit gas was analyzed to measure the concentration of degradation products. Plasma F- concentration increased during anesthesia, and decreased 3 h after termination. Individual maximum plasma F- concentrations were 38.8-88.6 mumol/L (56.6 +/- 4.7 mumol/L, mean +/- SE). Minimum alveolar anesthetic concentration (MAC) hours (1 MAC = 2.05%) exposure correlated with individual maximum plasma F- concentration (r2 = 0.68, P < 0.01). CF2 = C(CF3)-O-CH2F (compound A) was the only degradation product detected in the circuit. Its individual maximum concentrations were 13.6-35.1 ppm (24.3 +/- 2.4 ppm). Postanesthesia clinical laboratory tests showed no renal impairment and only mild hepatic dysfunction that was not associated with anesthesia. Hyperfluorinemia and minute quantities of compound A were detected following long-duration, low-flow sevoflurane anesthesia.

Background: Sevoflurane reacts with soda lime, generating degradation products. The concentrations of sevoflurane degradation products in a low-flow circuit have been reported for anesthesia times of less than 5 h. In this study, sevoflurane degradation products generated during low-flow anesthesia exceeding 10 h were examined., Methods: Sixteen patients received sevoflurane anesthesia with a fresh gas flow rate of 11/min. In eight patients, soda lime was used as the CO2 absorbent; in the other eight patients, Baralyme was used. During anesthesia, the concentrations of degradation products in the circuit, the temperature of the CO2 absorbent, inspired and end-tidal sevoflurane concentrations, and the volume of CO2 eliminated by the patient were measured. Gas was sampled from the inspiratory limb of the circuit and analyzed by gas chromatography., Results: Two degradation products, CF2 = C(CF3)-O-CH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B), were detected. In the soda lime group, the individual maximum concentration of compound A was 23.6 +/- 2.9 (12.0-37.4) ppm. In the Baralyme group, the concentration was 32.0 +/- 2.3 (23.5-41.3) ppm. The individual maximum concentration of compound A in the Baralyme group was significant higher than A in the Baralyme group was significant higher than that in the soda lime group. Compound B was detected in two patients, reaching a maximum concentration of 0.2 ppm. The end-tidal sevoflurane concentration, temperature of the CO2 absorbent, and volume of CO2 eliminated by the patient were the same in both groups., Conclusions: The degradation products detected were at low concentrations in long-duration, low-flow anesthesia with sevoflurane. Baralyme produced higher concentrations of degradation products than soda lime.

Engström Elsa Anesthesia System (Engström Elsa) was modified to make sevoflurane administration possible, and low-flow sevoflurane anesthesia using this modified anesthesia machine was administered to 10 surgical patients. Among the breakdown products of sevoflurane, CF2 = C (CF3) OCH2F (compound A) was 14.0 +/- 7.8 ppm after the first hour of anesthesia, and remained at this level until 7 hours. CH3OCF2CH(CF3)OCH2F (compound B) was detected in 3 of 10 patients, and these concentrations were below 0.5 ppm. No patient had clinical or laboratory evidence of organ toxicity. Low-flow sevoflurane anesthesia using modified Engström Elsa can be performed safely and easily. Although low levels of two breakdown products were detected, clinical laboratory tests showed no abnormality in hepatic or renal function.

The biological functions of platelet-activating factor (PAF) have been extensively studied in the rat. However, the precise structure and distribution of rat PAF receptor has not been reported. To address this question, we isolated a rat PAF-receptor cDNA from a size-fractionated rat spleen cDNA library. The deduced amino acid sequence of the rat PAF receptor showed 80% and 79% identity with guinea pig and human PAF receptors, respectively. Pharmacological properties (ED50, inhibition by WEB2086) of rat PAF receptors expressed in Xenopus oocytes were similar to those for PAF receptors expressed from guinea pig or human cDNAs. Northern blot analysis showed a widespread distribution of PAF-receptor mRNA in almost all organs including spleen, small intestine, kidney, lung, liver and brain. Considerable difference in the PAF-receptor distribution detected among species suggests the existence of a species-specific and tissue-specific regulatory mechanism for PAF-receptor-mRNA expression. Isolation of rat PAF-receptor cDNA should facilitate further analysis of PAF-receptor function and pharmacology in diverse pathophysiological processes.

Background: Sevoflurane reacts with CO2 absorbents, resulting in the generation of breakdown products. The concentrations of sevoflurane breakdown products in a low-flow system within 5 h have been reported, but concentrations in low-flow anesthesia exceeding 5 h or in closed-circuit anesthesia have not. In this study, the breakdown products of sevoflurane in closed-circuit anesthesia exceeding 5 h were examined., Methods: Closed-circuit sevoflurane anesthesia was administered to ten patients. Laboratory tests of hepatic and renal function were performed before and after anesthesia. Gas samples were obtained from the inspiratory limb of the anesthesia circuit, and breakdown products were analyzed by gas chromatography. The temperature of the soda lime was measured during anesthesia., Results: Among the breakdown products of sevoflurane, two products, CF2 = C(CF3)-O-CH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B), were detected. Compound A was detected in all measurements, and its concentration reached 19.5 +/- 5.4 ppm 1 h after anesthesia and decreased after 5 h. The highest concentration observed for compound A was 30.0 ppm. Compound B was detected in seven of the ten patients; its concentration was 0.17 +/- 0.37 ppm after 0.5 h of anesthesia and remained at similar concentrations thereafter. The highest mean temperature of the soda lime was 46.0 +/- 1.7 degrees C. Postanesthetic clinical laboratory tests showed no abnormalities in hepatic or renal function associated with anesthesia., Conclusions: Two breakdown products were detected in the patients anesthetized with sevoflurane using a closed-circuit technique. No abnormalities were observed during anesthesia, and no evidence of hepatic or renal dysfunction was noted in postoperative laboratory tests.

The human platelet-activating factor (PAF) receptor gene exists as a single copy on chromosome 1. We identified two 5'-noncoding exons, each of which has distinct transcriptional initiation sites. These exons are alternatively spliced to a common splice acceptor site on a third exon that contains the total open reading frame to yield two different species of functional mRNA (Transcript 1 and 2). Transcript 1 has consensus sequences for transcription factor NF-kappa B and Sp-1, and the Initiator (Inr) sequence homologous to the murine terminal deoxynucleotidyltransferase gene. Transcript 2 also contains consensus sequences for transcription factor AP-1, AP-2, and Sp-1. Transcripts 1 and 2 were both detected in heart, lung, spleen, and kidney, whereas only Transcript 1 was found in peripheral leukocytes, a differentiated human eosinophilic cell line (EoL-1 cells), and brain. Existence of distinct promoters was thus suggested to play a role in the regulatory control of PAF receptor gene expression in different human tissues and cells.

Leukotriene (LT) A4 hydrolase catalyzes enzymatic hydration of LTA4 to biologically active substance, LTB4. Biochemical and immuno-histochemical studies have shown that this enzyme is ubiquitously distributed in various cells and tissues. A sequence domain of LTA4 hydrolase was found to be homologous to those of several zinc metalloproteases. Both native and recombinant enzymes were shown to possess equimolar zinc ion and aminopeptidase activity. To examine the molecular mechanism of this enzyme reaction, site-directed mutagenesis experiments were carried out. Single amino acid substitutions at Glu-297 revealed a distinction of two enzyme activities, and suggest that the glutamic acid residue at 297 is essential for aminopeptidase, while the side chain of Glu or Gln is required for LTA4 hydrolase activity. The loss of two enzyme activities in a mutant E319K confirmed the proposal that the presence of a zinc ion in the enzyme is required for both enzyme activities.

The production of platelet-activating factor (PAF), an alkyl ether phospholipid, was previously shown to occur in the brain upon various stimuli, and binding sites for PAF have been reported. We have recently demonstrated the existence of functional mRNA for PAF receptor in the brain by using a Xenopus oocyte expression system (Bito et al. (1992) Neuron 9, 285-294). In this review, we have analyzed the binding characteristics of PAF receptor in the rat brain and show that PAF receptor is ubiquitously distributed in the rat central nervous system, with an emphasis to the hypothalamus, cerebral cortex, and olfactory bulb. PAF was also found to mobilize intracellular Ca2+ in rat hippocampus.

cDNA clones encoding three types of Gi alpha, the alpha subunit of GTP-binding protein (Gi1 alpha, Gi2 alpha, and Gi3 alpha), were isolated from a cDNA library of the guinea-pig lung. Nucleotide sequence analysis revealed a high degree of homology with other mammalian Gi alpha cDNAs. By RNA blot analysis, the expression pattern of Gi1 alpha was more tissue-specific than those of other types of Gi alphas in the guinea-pig tissues examined. While Gi2 alpha and Gi3 alpha mRNAs were ubiquitously expressed in all tissues examined, Gi1 alpha mRNA was mainly expressed in the brain, lung and kidney. These results suggest that each Gi alpha protein may have a different role.

We previously obtained evidence for intrinsic aminopeptidase activity for leukotriene (LT)A4 hydrolase, an enzyme characterized to specifically catalyse the hydrolysis of LTA4 to LTB4, a chemotactic compound. From a sequence homology search between LTA4 hydrolase and several aminopeptidases, it became clear that they share a putative active site for known aminopeptidases and a zinc binding domain. Thus, Glu-297 of LTA4 hydrolase is a candidate for the active site of its aminopeptidase activity, while His-296, His-300 and Glu-319 appear to constitute a zinc binding site. To determine whether or not this putative active site is also essential to LTA4 hydrolase activity, site-directed mutagenesis experiments were carried out. Glu-297 was mutated into 4 different amino acids. The mutant E297Q (Glu changed to Gln) conserved LTA4 hydrolase activity but showed little aminopeptidase activity. Other mutants at Glu-297 (E297A, E297D and E297K) showed markedly reduced amounts of both activities. It is thus proposed that either a glutamic or glutamine moiety at 297 is required for full LTA4 hydrolase activity, while the free carboxylic acid of glutamic acid is essential for aminopeptidase.

A comparison of amino acid sequences revealed that leukotriene A4 (LTA4) hydrolase is homologous to various types of aminopeptidases. Consistently with the finding, the purified LTA4 hydrolases from both human and guinea pig sources contained equimolar zinc ion, as determined by atomic absorption spectrometry. The enzyme had a significant amount of aminopeptidase activity toward synthetic peptide substrates. Both LTA4 hydrolase and aminopeptidase activities were inhibited by o-phenanthroline, p-chloromercuribenzoic acid, and Leu-thiol with similar IC50 values. Co-purification as well as co-immunoprecipitation of both enzyme activities with an affinity-purified antibody against LTA4 hydrolase strongly suggest that the two enzyme activities reside in a single protein.

Leukotriene A4 hydrolase was purified to apparent homogeneity from the guinea pig lung. The molecular weight was determined to be 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme exhibited two active forms with different pI values (5.7 and 5.4) depending on the presence or absence of SH-reducing reagents during purification procedures. No significant differences were observed between both forms of the enzyme as regards the catalytic properties. The N-terminal 20 amino acid sequence (PEVVDTXSLASPATVXRTKH) showed a 90% identity to the human enzyme with a constitutive substitution of Ile-3 and Ser-14 (human) by Val-3 and Thr-14 (guinea pig), respectively.