A Swiss anaesthesiology closed claims analysis: report of events in the years 1987-2008.

BACKGROUND AND OBJECTIVE: In 1999, the Swiss Society of Anaesthesiology and Reanimation (SSAR) initiated an analysis of closed malpractice claims filed against anaesthetists in a project intended to improve patient safety. This article discusses the results of a review of closed claims between 1987 and 2008 and filed up to the end of 2009. METHODS: Records of closed claims were provided by Swiss professional medical liability insurance companies and the Office for Extrajudicial Expert Review of the Swiss Medical Association. Data were collected by an onsite reviewer, converted into a standardised format and sent to the SSAR Closed Claims Study Group.Assessment criteria employed by the committee were level of care (standard or substandard); severity of injury; appropriateness of patient information; and consent. RESULTS: The records of 171 events leading to anaesthesia-related injuries were entered into the database. These injuries occurred within the period 1987-2008. The majority of claims (54%) were related to regional anaesthesia, with general anaesthesia accounting for 28% and other anaesthesia-related procedures for 18%. The quality of care was judged by the committee to be substandard in 55% of cases, and liability was accepted in 46% of all claims. Negative outcomes were death in 12% and permanent injury in 63% of the patients. CONCLUSION: The closed claims analysis project enabled the SSAR to identify areas of high medicolegal risks to gain an insight into the causes of infrequent but potentially harmful events leading to anaesthesia-related injuries and, based on these data, to develop preventive strategies.

Alveolar macrophages regulate neutrophil recruitment in endotoxin-induced lung injury.

BACKGROUND: Alveolar macrophages play an important role during the development of acute inflammatory lung injury. In the present study, in vivo alveolar macrophage depletion was performed by intratracheal application of dichloromethylene diphosphonate-liposomes in order to study the role of these effector cells in the early endotoxin-induced lung injury. METHODS: Lipopolysaccharide was applied intratracheally and the inflammatory reaction was assessed 4 hours later. Neutrophil accumulation and expression of inflammatory mediators were determined. To further analyze in vivo observations, in vitro experiments with alveolar epithelial cells and alveolar macrophages were performed. RESULTS: A 320% increase of polymorphonuclear leukocytes in bronchoalveolar lavage fluid was observed in macrophage-depleted compared to macrophage-competent lipopolysaccharide-animals. This neutrophil recruitment was also confirmed in the interstitial space. Monocyte chemoattractant protein-1 concentration in bronchoalveolar lavage fluid was significantly increased in the absence of alveolar macrophages. This phenomenon was underlined by in vitro experiments with alveolar epithelial cells and alveolar macrophages. Neutralizing monocyte chemoattractant protein-1 in the airways diminished neutrophil accumulation. CONCLUSION: These data suggest that alveolar macrophages play an important role in early endotoxin-induced lung injury. They prevent neutrophil influx by controlling monocyte chemoattractant protein-1 production through alveolar epithelial cells. Alveolar macrophages might therefore possess robust anti-inflammatory effects.

The effect of clonidine on perioperative blood coagulation.

STUDY OBJECTIVE: To evaluate the influence of perioperative stress protection by clonidine on blood coagulation. DESIGN: Prospective, randomized, double-blinded, placebo-controlled clinical trial. SETTING: University hospital. PATIENTS: 50 patients scheduled for elective gynecoabdominal surgery. INTERVENTIONS AND MEASUREMENTS: Patients were randomly assigned to control (placebo) or clonidine group (single intravenous clonidine dose; 4 microg/kg(-1) or 3 microg/kg(-1) for age >65 years). Three measurement time points were defined: before administration of placebo/clonidine and anesthesia induction, (t1; baseline measurement); after surgery, before emergence of anesthesia (t2); and at the first postoperative day, 24 hours after anesthesia induction (t3). Blood coagulation was analyzed at all time points measuring international normalized ratio, platelets, thrombin-antithrombin complex, von Willebrand factor, soluble thrombomodulin, d-dimers, plasminogen activator inhibitor 1, and Thrombelastograph analysis. MAIN RESULTS: In the postoperative period (t2, t3), hypercoagulability was present in all patients compared with baseline measurements (t1) but without differences between the control and clonidine group. Regarding hematologic, laboratory blood coagulation, and Thrombelastograph parameters, there was no statistically and clinically relevant difference throughout the study period between the 2 groups. No hemodynamic adverse events of clonidine were observed in the perioperative period. Until day of discharge, no thrombotic or thromboembolic events were reported in both groups. CONCLUSIONS: Preoperative administration of a single dose of clonidine has no effect on perioperative blood coagulation.

Ischemic but not pharmacological preconditioning elicits a gene expression profile similar to unprotected myocardium.

Pharmacological (PPC) and ischemic preconditioning (IschPC) provide comparable protection against ischemia in the heart. However, the genomic phenotype may depend on the type of preconditioning. Isolated perfused rat hearts were used to evaluate transcriptional responses to PPC and IschPC in the presence (mediator/effector response) or absence (trigger response) of 40 min of test ischemia using oligonucleotide microarrays. IschPC was induced by 3 cycles of 5 min of ischemia, and PPC by 15 min of 2.1 vol% isoflurane. Unsupervised analysis methods were used to identify gene expression patterns. PPC and IschPC were accompanied by marked alterations in gene expression. PPC and IschPC shared only approximately 25% of significantly up- and downregulated genes after triggering. The two types of preconditioning induced a more uniform genomic response after ischemia/reperfusion. Numerous genes separated preconditioned from unprotected ischemic hearts. Three stable gene clusters were identified in the trigger response to preconditioning, while eight stable clusters related to cytoprotection, inflammation, remodeling, and long interspersed nucleotide elements (LINEs) were delineated after prolonged ischemia. A single stable sample cluster emerged from cluster analysis for both IschPC and unprotected myocardium, indicating a close molecular relationship between these two treatments. Principal component analysis revealed differences between PPC vs. IschPC, and trigger vs. mediator/effector responses in transcripts predominantly related to biosynthesis and apoptosis. IschPC and PPC similarly but distinctly reprogram the genetic response to ischemic injury. IschPC elicits a postischemic gene expression profile closer to unprotected myocardium than PPC, which may be therefore more advantageous as therapeutic strategy in cardioprotection.

ABCA1 modulates CSF cholesterol levels and influences the age at onset of Alzheimer's disease.

Increased formation of the beta-amyloid peptide (Abeta) is a central event in the pathogenesis of Alzheimer's disease (AD). High cellular cholesterol load promotes Abeta formation. The ATP-binding cassette transporter A1 (ABCA1) mediates cholesterol efflux from cells. We hypothesized that genetic variability in ABCA1 may influence cholesterol metabolism in the central nervous system (CNS) and, thus, interfere with the development of AD. Healthy elderly carriers of the A allele of a non-synonymous (R219K) single nucleotide polymorphism (SNP) in the ABCA1 gene (rs2234884) had on average 33% lower total cholesterol in cerebrospinal fluid (CSF) than non-carriers. In 169 patients with late onset, sporadic AD, this allele was associated with delayed age at onset of the disease by 1.7 years on average. Rs2234884 and another non-synonymous SNP (R1587K) in ABCA1 (rs2234886) failed to show significant association with the risk for AD. We conclude that genetic variability of ABCA1 influences the development of AD, possibly by interfering with CNS cholesterol homeostasis.

Increased brain beta-amyloid load, phosphorylated tau, and risk of Alzheimer disease associated with an intronic CYP46 polymorphism.

BACKGROUND: CYP46, the gene encoding cholesterol 24-hydroxylase, plays a key role in the hydroxylation of cholesterol and thereby mediates its removal from brain. OBJECTIVE: To study the association of polymorphic sites on CYP46 with Alzheimer disease (AD) traits and with the risk of the development of AD. DESIGN: Alzheimer disease traits (beta-amyloid load, beta-amyloid peptides, hyperphosphorylated tau protein) were assessed in brain tissues and in the cerebrospinal fluid of patients with AD and control subjects. Genetic associations were studied in 2 independent populations. SETTING: Specialized centers for memory disorders in Switzerland, Greece, and Italy. PARTICIPANTS: Fifty-five brain tissues from nondemented elderly patients for the histopathological studies; 38 patients with AD and 25 control subjects for the cerebrospinal fluid studies; 201 patients with AD and 248 control subjects for the genetic association studies. RESULTS: A polymorphism of CYP46 was associated with increased beta-amyloid load in brain tissues as well as with increased cerebrospinal fluid levels of beta-amyloid peptides and phosphorylated tau protein. Moreover, this CYP46 polymorphism was associated with higher risk of late-onset sporadic AD in 2 independent populations (odds ratio, 2.16; 95% confidence interval [CI], 1.41-3.32; P<.001). The additional presence of 1 or 2 apolipoprotein E epsilon4 alleles synergistically increased the risk of AD to an odds ratio of 9.6 (95% CI, 4.9-18.9; P<.001) as compared with 4.4 for apolipoprotein E epsilon4 alone (95% CI, 2.8-6.8; P<.001). CONCLUSION: CYP46 influences brain beta-amyloid load, cerebrospinal fluid levels of beta-amyloid peptides and phosphorylated tau, and the genetic risk of late-onset sporadic AD.

Genetic polymorphisms and cerebrospinal fluid levels of tissue inhibitor of metalloproteinases 1 in sporadic Alzheimer's disease.

Tissue inhibitor of metalloproteinases 1 (TIMP-1) inhibits several proteinases including a disintegrin and metalloproteinase 10 (ADAM10), a major alpha-secretase that cleaves the beta-amyloid precursor protein within its amyloidogenic Abeta domain. The gene encoding TIMP-1 (TIMP 1) maps to the short arm of the X chromosome, in a region previously suggested as conferring genetic susceptibility for Alzheimer's disease (AD). To determine whether genetic variability of TIMP 1 contributes to the pathogenesis of AD, we analysed one single nucleotide polymorphism within TIMP 1 and one single nucleotide polymorphism in the 5'-untranslated region of TIMP 1 in patients with AD and control subjects from two independent and ethnically different populations. We did not observe any association between TIMP 1 genotypes and the diagnosis of AD in men or women. We also measured TIMP-1 protein levels in the cerebrospinal fluid of patients with AD, healthy control subjects, and patients with other neurological disorders. TIMP-1 levels were similar in all groups. In addition, no significant differences were observed after stratification for TIMP 1 genotypes. Our data show that neither genetic variability nor protein levels of TIMP-1 are associated with AD.

Ropivacaine decreases inflammation in experimental endotoxin-induced lung injury.

BACKGROUND: Endotoxin causes acute lung injury, which can lead to acute respiratory distress syndrome. Because local anesthetics are known to attenuate inflammatory reactions, ropivacaine was tested for its possible antiinflammatory effect in lipopolysaccharide-induced lung injury in rat alveolar epithelial cells (AECs) and rat pulmonary artery endothelial cells (RPAECs) in vitro and in vivo. METHODS: AECs and RPAECs were stimulated for 4 h with lipopolysaccharide or lipopolysaccharide and 1 mum ropivacaine. Messenger RNA (mRNA) for intercellular adhesion molecule 1 was assessed. Isolated neutrophils were incubated with stimulated target cells to quantify adhesion and neutrophil-induced cytotoxicity in AECs and RPAECs. In vivo, lipopolysaccharide was instilled intratracheally with or without 1 mm intratracheally or intravenously administered ropivacaine. Bronchoalveolar lavage was performed 5 h later to determine neutrophil and albumin content, as well as concentrations of inflammatory mediators. RESULTS: In AECs and RPAECs, ropivacaine attenuated lipopolysaccharide-induced up-regulation of mRNA for intercellular adhesion molecule 1 by 41% and 24%, respectively (P < 0.05). In the presence of ropivacaine, increased neutrophil adhesion was down-regulated by 58% and 44% (P < 0.005), whereas cytotoxicity in AECs and RPAECs was diminished by 28% and 33%, respectively (P < 0.05). Enhanced neutrophil count in lipopolysaccharide lungs was reduced by 56% in the presence of intratracheally instilled ropivacaine (81% with intravenous ropivacaine; P < 0.005). Albumin was decreased by 46% with intratracheal ropivacaine (38% with intravenous ropivacaine; P < 0.05), and inflammatory mediators were decreased by 48-59% (69-81% with intravenous ropivacaine; P < 0.01). CONCLUSIONS: Ropivacaine intervention substantially attenuated the inflammatory response in acute lung injury and thus may carry an interesting potential for antiinflammatory treatment.

Infarct-remodeled myocardium is receptive to protection by isoflurane postconditioning: role of protein kinase B/Akt signaling.

BACKGROUND: Postinfarct remodeled myocardium exhibits numerous structural and biochemical alterations. So far, it is unknown whether postconditioning elicited by volatile anesthetics can also provide protection in the remodeled myocardium. METHODS: Myocardial infarct was induced in male Wistar rats by ligation of the left anterior descending coronary artery. Six weeks later, hearts were buffer-perfused and exposed to 40 min of ischemia followed by 90 min of reperfusion. Anesthetic postconditioning was induced by 15 min of 2.1 vol% isoflurane. In some experiments, LY294002 (15 microM), a phosphatidylinositol 3-kinase inhibitor, was coadministered with isoflurane. Masson's trichrome staining, immunohistochemistry, Western blot analysis, and reverse-transcription polymerase chain reaction served to confirm remodeling. In buffer-perfused hearts, functional recovery was recorded, and acute infarct size was measured using 1% triphenyltetrazolium chloride staining and lactate dehydrogenase release during reperfusion. Western blot analysis was used to determine phosphorylation of reperfusion injury salvage kinases including protein kinase B/Akt and its downstream targets after 15 min of reperfusion. RESULTS: Infarct hearts exhibited typical macroscopic and molecular changes of remodeling. Isoflurane postconditioning improved functional recovery and decreased acute infarct size, as determined by triphenyltetrazolium (35 +/- 5% in unprotected hearts vs. 8 +/- 3% in anesthetic postconditioning; P < 0.05) and lactate dehydrogenase release. This protection was abolished by LY294002, which inhibited phosphorylation of protein kinase B/Akt and its downstream targets glycogen synthase kinase 3beta, endothelial nitric oxide synthase, and p70S6 kinase. CONCLUSIONS: Infarct-remodeled myocardium is receptive to protection by isoflurane postconditioning via protein kinase B/Akt signaling. This is the first time to demonstrate that anesthetic postconditioning retains its marked protection in diseased myocardium.

Inflammatory response of tracheobronchial epithelial cells to endotoxin.

Respiratory epithelial cells play a crucial role in the inflammatory response in endotoxin-induced lung injury, an experimental model for acute lung injury. To determine the role of epithelial cells in the upper respiratory compartment in the inflammatory response to endotoxin, we exposed tracheobronchial epithelial cells (TBEC) to lipopolysaccharide (LPS). Expression of inflammatory mediators was analyzed, and the biological implications were assessed using chemotaxis and adherence assays. Epithelial cell necrosis and apoptosis were determined to identify LPS-induced cell damage. Treatment of TBEC with LPS induced enhanced protein expression of cytokines and chemokines (increases of 235-654%, P < 0.05), with increased chemotactic activity regarding neutrophil recruitment. Expression of the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was enhanced by 52-101% (P < 0.0001). This upregulation led to increased adhesion of neutrophils, with >95% adherence to TBEC after LPS stimulation, which could be blocked by either ICAM-1 (69%) or VCAM-1 antibodies (55%) (P < 0.05). Enhanced neutrophil-induced necrosis of TBEC was observed when TBEC were exposed to LPS. Reduced neutrophil adherence by ICAM-1 or VCAM-1 antibodies resulted in significantly lower TBEC death (52 and 34%, respectively, P < 0.05). Therefore, tight adherence of neutrophils to TBEC appears to promote epithelial cell killing. In addition to indirect effector cell-induced TBEC death, direct LPS-induced cell damage was seen with increased apoptosis rate in LPS-stimulated TBEC (36% increase of caspase-3, P < 0.01). These data provide evidence that LPS induces TBEC killing in a necrosis- and apoptosis-dependent manner.

Isoflurane postconditioning prevents opening of the mitochondrial permeability transition pore through inhibition of glycogen synthase kinase 3beta.

BACKGROUND: Postischemic administration of volatile anesthetics activates reperfusion injury salvage kinases and decreases myocardial damage. However, the mechanisms underlying anesthetic postconditioning are unclear. METHODS: Isolated perfused rat hearts were exposed to 40 min of ischemia followed by 1 h of reperfusion. Anesthetic postconditioning was induced by 15 min of 2.1 vol% isoflurane (1.5 minimum alveolar concentration) administered at the onset of reperfusion. In some experiments, atractyloside (10 microm), a mitochondrial permeability transition pore (mPTP) opener, and LY294002 (15 microm), a phosphatidylinositol 3-kinase inhibitor, were coadministered with isoflurane. Western blot analysis was used to determine phosphorylation of protein kinase B/Akt and its downstream target glycogen synthase kinase 3beta after 15 min of reperfusion. Myocardial tissue content of nicotinamide adenine dinucleotide served as a marker for mPTP opening. Accumulation of MitoTracker Red 580 (Molecular Probes, Invitrogen, Basel, Switzerland) was used to visualize mitochondrial function. RESULTS: Anesthetic postconditioning significantly improved functional recovery and decreased infarct size (36 +/- 1% in unprotected hearts vs. 3 +/- 2% in anesthetic postconditioning; P < 0.05). Isoflurane-mediated protection was abolished by atractyloside and LY294002. LY294002 inhibited isoflurane-induced phosphorylation of protein kinase B/Akt and glycogen synthase kinase 3beta and opened mPTP as determined by nicotinamide adenine dinucleotide measurements. Atractyloside, a direct opener of the mPTP, did not inhibit phosphorylation of protein kinase B/Akt and glycogen synthase kinase 3beta by isoflurane but reversed isoflurane-mediated cytoprotection. Microscopy showed accumulation of the mitochondrial tracker in isoflurane-protected functional mitochondria but no staining in mitochondria of unprotected hearts. CONCLUSIONS: Anesthetic postconditioning by isoflurane effectively protects against reperfusion damage by preventing opening of the mPTP through inhibition of glycogen synthase kinase 3beta.

Patterns of changes in arterial PO2 during one-lung ventilation: a comparison between patients with severe pulmonary emphysema and patients with preserved lung function.

OBJECTIVES: One-lung ventilation (OLV) during thoracoscopic surgery is associated with a significant decline in arterial PO(2) in patients with severe pulmonary emphysema and patients with preserved lung function. The authors hypothesized that patterns of arterial PO(2) changes are different in these 2 patient groups. DESIGN: Prospective nonrandomized study. SETTING: University hospital. PARTICIPANTS: Twenty-five patients undergoing thoracoscopic interventions: 16 with severe pulmonary emphysema and 9 patients without emphysema. INTERVENTIONS: Continuous arterial blood gas measurement (PaO(2), PaCO(2), pHa) during OLV of the left lung in left lateral position using the Paratrend 7 blood gas monitoring system (PT7; Pfizer Hospital Products Group, High Wycombe, UK). MAIN RESULTS: The decrease of PaO(2) was delayed in patients with severe emphysema. Steady state (defined as DeltaPaO(2) <7.5 mmHg/min) was reached after 18 +/- 4 minutes compared with 11 +/- 3 minutes (mean +/- standard deviation) in patients with normal lung function (p = 0.0002). PaO(2) values at steady state were comparable (p = 0.49); the pattern of changes in PaO(2) for the first 15 minutes of left-sided OLV was significantly different between the groups (p = 0.0004). The difference of predicted versus measured PaO(2) at steady state was -48 +/- 160 mmHg for patients with emphysema and -51 +/- 60 mmHg for patients with normal lung function (p = 0.019). CONCLUSION: During OLV, oxygenation is better preserved for a longer period of time in patients with severe pulmonary emphysema as compared with patients with normal lung function. In contrast to patients without emphysema, prediction of oxygenation during OLV for the individual patient with emphysema is unreliable because of large interindividual differences.

Pulmonary aspiration: new therapeutic approaches in the experimental model.

BACKGROUND: Acute lung injury caused by gastric aspiration is a frequent occurrence in unconscious patients. Acute respiratory distress syndrome in association with gastric aspiration carries a mortality of up to 30% and accounts for up to 20% of deaths associated with anesthesia. Although the clinical condition is well known, knowledge about the exact inflammatory mechanisms is still incomplete. This study was performed to define the role of alveolar macrophages in this inflammatory response. In addition, potentially modifying effects of intratracheally applied nuclear factor kappaB inhibitor pyrrolidine dithiocarbamate were investigated. METHODS: Rat alveolar macrophages were depleted by intratracheal administration of clodronate liposomes, and lung injury was evaluated 6 h after instillation of 0.1N hydrochloric acid. In a second set of experiments, pyrrolidine dithiocarbamate was intratracheally instilled 3 h after hydrochloric acid application, and injury parameters were determined. RESULTS: Depletion of alveolar macrophages resulted in decreased production of inflammatory mediators in acid aspiration (23-80% reduction of messenger RNA or protein of inflammatory mediators; P < 0.05) and consequently also in diminished neutrophil recruitment (36% fewer neutrophils; P < 0.01). Treatment with pyrrolidine dithiocarbamate was highly effective in decreasing neutrophil recruitment (66%; P < 0.01) and vascular permeability (80%; P < 0.001). CONCLUSIONS: These data suggest that alveolar macrophages play an essential role in the inflammatory response of acid-induced lung injury. For the first time, attenuation of acid-induced lung injury with an inhibitor, applied after the onset of injury, is shown.

Cholesterol 25-hydroxylase on chromosome 10q is a susceptibility gene for sporadic Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia. It is characterized by beta-amyloid (A beta) plaques, neurofibrillary tangles and the degeneration of specifically vulnerable brain neurons. We observed high expression of the cholesterol 25-hydroxylase (CH25H) gene in specifically vulnerable brain regions of AD patients. CH25H maps to a region within 10q23 that has been previously linked to sporadic AD. Sequencing of the 5' region of CH25H revealed three common haplotypes, CH25Hchi2, CH25Hchi3 and CH25Hchi4; CSF levels of the cholesterol precursor lathosterol were higher in carriers of the CH25Hchi4 haplotype. In 1,282 patients with AD and 1,312 healthy control subjects from five independent populations, a common variation in the vicinity of CH25H was significantly associated with the risk for sporadic AD (p = 0.006). Quantitative neuropathology of brains from elderly non-demented subjects showed brain A beta deposits in carriers of CH25Hchi4 and CH25Hchi3 haplotypes, whereas no A beta deposits were present in CH25Hchi2 carriers. Together, these results are compatible with a role of CH25Hchi4 as a putative susceptibility factor for sporadic AD; they may explain part of the linkage of chromosome 10 markers with sporadic AD, and they suggest the possibility that CH25H polymorphisms are associated with different rates of brain A beta deposition.

Volatile anesthetics mimic cardiac preconditioning by priming the activation of mitochondrial K(ATP) channels via multiple signaling pathways.

BACKGROUND: Volatile anesthetics induce pharmacological preconditioning in cardiac tissue. The purpose of this study was to test whether volatile anesthetics mediate this effect by activation of the mitochondrial adenosine triphosphate-sensitive potassium (mitoK(ATP)) or sarcolemmal K(ATP) (sarcK(ATP)) channel in rat ventricular myocytes and to evaluate the signaling pathways involved. METHODS: A cellular model of ischemia with subsequent hypoosmolar trypan blue staining served to determine the effects of 5-hydroxydecanoate, a selective mitoK(ATP) channel blocker, HMR-1098, a selective sarcK(ATP) channel blocker, diazoxide, a preconditioning mimicking agent, and various modulators of putative signaling pathways on cardioprotection elicited by sevoflurane and isoflurane. Microscopy was used to visualize and measure autofluorescence of flavoproteins, a direct index of mitoK(ATP) channel activity. RESULTS: Volatile anesthetics significantly enhanced diazoxide-mediated activation of mitoK(ATP) channels as assessed by autofluorescence of myocytes. Conversely, volatile anesthetics alone did not alter mitoK(ATP) channel activity, implying a priming effect of volatile anesthetics on mitoK(ATP) channels. Administration of the protein kinase C inhibitor chelerythrine completely blocked this effect. Also, pretreatment with volatile anesthetics potentiated diazoxide-mediated protection against ischemia, as indicated by a reduction in trypan blue-positive myocytes. Importantly, cardioprotection afforded by volatile anesthetics was unaffected by the sarcK(ATP) channel blocker HMR-1098 but sensitive to modulations of nitric oxide and adenosine-G(i) signaling pathways. CONCLUSIONS: Using autofluorescence in live cell imaging microscopy and a simulated model of ischemia, the authors present evidence that volatile anesthetics mediate their protection in cardiomyocytes by selectively priming mitoK(ATP) channels through multiple triggering protein kinase C-coupled signaling pathways. These observations provide important new insight into the mechanisms of anesthetic-induced preconditioning.

Differential effects of anesthetics on mitochondrial K(ATP) channel activity and cardiomyocyte protection.

BACKGROUND: Mitochondrial adenosine triphosphate-sensitive potassium (mitoK(ATP)) channels play a pivotal role in mediating cardiac preconditioning. The effects of intravenous anesthetics on this protective channel have not been investigated so far, but would be of importance with respect to experimental as well as clinical medicine. METHODS: Live cell microscopy was used to visualize and measure autofluorescence of flavoproteins, a direct reporter of mitoK(ATP) channel activity, in response to the direct and highly selective mitoK(ATP) channel opener diazoxide, or to diazoxide following exposure to various anesthetics commonly used in experimental and clinical medicine. A cellular model of ischemia with subsequent hypoosmolar trypan blue staining served to substantiate the effects of the anesthetics on mitoK(ATP) channels with respect to myocyte viability. RESULTS: Diazoxide-induced mitoK(ATP) channel opening was significantly inhibited by the anesthetics R-ketamine, and the barbiturates thiopental and pentobarbital. Conversely, urethane, 2,2,2-trichloroethanol (main metabolite of alpha-chloralose and chloral hydrate), and the opioid fentanyl potentiated the channel-opening effect of diazoxide, which was abrogated by coadministration of chelerythrine, a specific protein kinase C inhibitor. S-ketamine, propofol, xylazine, midazolam, and etomidate did not affect mitoK(ATP) channel activity. The significance of these modulatory effects of the anesthetics on mitoK(ATP) channel activity was substantiated in a cellular model of simulated ischemia, where diazoxide-induced cell protection was mitigated by R-ketamine and the barbiturates, while urethane, 2,2,2-trichloroethanol, and fentanyl potentiated myocyte protection. CONCLUSIONS: These results suggest distinctive actions of individual anesthetics on mitoK(ATP) channels and provide evidence that the choice of background anesthesia may play a role in cardiac protection in both experimental and clinical medicine.

Differential activation of mitogen-activated protein kinases in ischemic and anesthetic preconditioning.

BACKGROUND: Accumulating evidence pinpoints to the pivotal role of mitogen-activated protein kinases (MAPKs) in the signal transduction underlying cardiac preconditioning. METHODS: PD98059, an inhibitor of extracellular signal-regulated protein kinase (MEK-ERK1/2), and SB203580, an inhibitor of p38 MAPK, were used to evaluate the role of MAPKs with respect to postischemic functional recovery in isolated perfused rat hearts subjected to ischemic preconditioning (IPC) and anesthetic preconditioning (APC). Western blot analyses were used to determine the degree of ERK1/2 and p38 MAPK activation after the application of the preconditioning stimulus and after ischemia-reperfusion. Immunohistochemical staining served to visualize subcellular localization of activated MAPKs. RESULTS: PD98059 and SB203580 abolished postischemic functional recovery in IPC but not in APC. IPC but not APC markedly activated ERK1/2 and p38 MAPK, which were abrogated by coadministration of the specific blockers. Conversely, IPC and APC enhanced ERK1/2 activity after ischemia-reperfusion as compared to nonpreconditioned hearts, and IPC in addition enhanced p38 MAPK activity. Coadministration of PD98059 and SB203580 during IPC but not during APC inhibited postischemically enhanced MAPK activities. Moreover, chelerythrine and 5-hydroxydecanoate, effective blockers of IPC and APC, annihilated IPC- and APC-induced enhanced postischemic responses of MAPKs. Finally, administration of PD98059 during ischemia-reperfusion diminished the protective effects of IPC and APC. Immunohistochemistry revealed increased ERK1/2 activity primarily in intercalated discs and nuclei and increased p38 MAPK activity in the sarcolemma and nuclei of IPC-treated hearts. CONCLUSIONS: Although MAPKs may orchestrate cardioprotection as triggers and mediators in IPC, they are devoid of triggering, but they may have mediator effects in APC.

Translocation of protein kinase C isoforms to subcellular targets in ischemic and anesthetic preconditioning.

BACKGROUND: Translocation of protein kinase C (PKC) to subcellular targets is a pivotal signaling step in ischemic preconditioning (IPC). However, to date, it is unknown whether PKC isoforms translocate in anesthetic preconditioning (APC). METHODS: The PKC blockers chelerythrine and rottlerin and the adenosine triphosphate-dependent potassium (K(ATP)) channel blockers HMR-1098 and 5-hydroxydecanoate were used to assess the role of PKC and K(ATP) channels in isolated perfused rat hearts subjected to IPC or APC (1.5 minimum alveolar concentration isoflurane) followed by 40 min of ischemia and 30 min of reperfusion. Immunohistochemical techniques were used to visualize PKC translocation after preconditioning. In addition, the phosphorylation status of PKC isoforms was assessed. RESULTS: Chelerythrine, rottlerin, and 5-hydroxydecanoate blocked IPC and APC with respect to functional recovery, albeit IPC at higher concentrations. HMR-1098 did not affect IPC or APC. PKCdelta and PKCepsilon translocated to nuclei in both IPC and APC, which was inhibited by chelerythrine and rottlerin. PKCdelta translocated to mitochondria but not to the sarcolemma, and PKCepsilon translocated to the sarcolemma and intercalated disks but not to mitochondria. Interestingly, PKCepsilon was accumulated at the intercalated disks in control and preconditioned hearts. Phosphorylation of PKCdelta on serine643 was increased in IPC and APC and blocked by chelerythrine and rottlerin, whereas phosphorylation of PKCdelta on threonine505 was increased only in IPC and not blocked by chelerythrine or rottlerin. PKCepsilon on serine729 did not change its phosphorylation status. CONCLUSIONS: This study indicates that translocation of PKCdelta plays a pivotal role in IPC and APC and suggests that phosphorylation of PKCdelta on serine643 may be of particular relevance in transferring the APC stimulus to mitochondrial K(ATP) channels.

Acid-induced lung injury: role of nuclear factor-kappaB.

BACKGROUND: Aspiration of acidic gastric contents leads to acute lung injury and is still one of the most common clinical events associated with acute lung injury. This study was performed to assess acid-induced lung inflammation in vitro and in vivo with respect to the time pattern of activated transcription factor nuclear factor-kappaB (NF-kappaB) and proinflammatory molecules. METHODS: L2 cells (alveolar epithelial cells) were exposed for various periods to a medium with a pH of 6. In the in vivo model, 1 ml/kg of 0.1 n acidic solution was instilled into the lungs of rats. NF-kappaB binding activity and expression pattern of inflammatory mediators were determined. Blocking studies were performed with the NF-kappaB inhibitor pyrrolidine dithiocarbamate. RESULTS: In vitro NF-kappaB binding activity showed a biphasic expression pattern with a first peak at 1 h and a second one at 6-8 h. In acid-injured rat lungs, NF-kappaB binding activity was confirmed in a biphasic manner with a first increase at 0.5-2 h (608 +/- 93% and 500 +/- 15%, respectively, P < 0.05) and a second peak at 8 h (697 +/- 35% increase, P < 0.005). Whole lung mRNA for macrophage inflammatory protein-1beta and macrophage inflammatory protein-2 showed a similar expression pattern, which could explain the biphasic neutrophil recruitment. Intratracheal pyrrolidine dithiocarbamate attenuated lung injury as evidenced by a reduction of neutrophil accumulation and expression of inflammatory mediators. CONCLUSIONS: These data suggest that NF-kappaB binding activity plays a key role in molecular and cellular events in acid-induced lung injury.

Accuracy and performance of a modified continuous intravascular blood gas monitoring device during thoracoscopic surgery.

OBJECTIVE: The only commercially available continuous intravascular blood gas monitoring system for adults, the Paratrend (Diametrics Medical Inc, High Wycombe, UK), was modified by the manufacturer to the Paratrend 7+ (PT7+) in 1999. The aim of this study was to evaluate the modified probe over a wide range of blood gas and pH values during thoracoscopic surgery in a similar setup as done with the previous model. DESIGN: Prospective methods comparison study. SETTING: University hospital. PARTICIPANTS: Twenty-three patients. INTERVENTIONS: Elective thoracoscopic surgery. MEASUREMENTS AND MAIN RESULTS: One hundred thirteen PT7+ readings and their corresponding arterial blood gas and pH measurements (ABGA) were evaluated. The ranges for ABGA values were 50 to 474 mmHg for PO(2), 29 to 58 mmHg for PCO(2), and 7.28 to 7.49 for pH. Bland and Altman analysis revealed a bias +/- 2 standard deviation of -20 +/- 86 mmHg for PO(2), 3 +/- 9 mmHg for PCO(2), and -0.01 +/- 0.06 for pH. No specific complications attributable to the probe were observed. CONCLUSION: In patients undergoing thoracoscopic surgery with rapidly changing blood gas parameters, the PT7+ device is a valuable trend indicator and hence may be helpful for clinical decision making. However, the underestimation of PO(2) values by 20 mmHg on average and the wide limits of agreement documented in this study must be regarded as limiting factors.