Proteomic Analysis Reveals Potential Exosomal Biomarkers in Patients With Sporadic Alzheimer Disease.

BACKGROUND: Despite substantial progress made in the past decades, the pathogenesis of sporadic Alzheimer disease (sAD) and related biological markers of the disease are still controversially discussed. Cerebrospinal fluid and functional brain imaging markers have been established to support the clinical diagnosis of sAD. Yet, due to the invasiveness of such diagnostics, less burdensome markers have been increasingly investigated in the past years. Among such markers, extracellular vesicles may yield promise in (early) diagnostics and treatment monitoring in sAD. MATERIALS AND METHODS: In this pilot study, we collected the blood plasma of 18 patients with sAD and compared the proteome of extracted extracellular vesicles with the proteome of 11 age-matched healthy controls. The resulting proteomes were characterized by Gene Ontology terms and between-group statistics. RESULTS: Ten distinct proteins were found to significantly differ between sAD patients and controls (P<0.05, False Discovery Rate, corrected). These proteins included distinct immunoglobulins, fibronectin, and apolipoproteins. CONCLUSIONS: These findings lend further support for exosomal changes in neurodegenerative disorders, and particularly in sAD. Further proteomic research could decisively advance our knowledge of sAD pathophysiology as much as it could foster the development of clinically meaningful biomarkers.

Extracellular Vesicles as Possible Plasma Markers and Mediators in Patients with Sepsis-Associated Delirium-A Pilot Study.

Patients with sepsis-associated delirium (SAD) show severe neurological impairment, often require an intensive care unit (ICU) stay and have a high risk of mortality. Hence, useful biomarkers for early detection of SAD are urgently needed. Extracellular vesicles (EVs) and their cargo are known to maintain normal physiology but also have been linked to numerous disease states. Here, we sought to identify differentially expressed proteins in plasma EVs from SAD patients as potential biomarkers for SAD. Plasma EVs from 11 SAD patients and 11 age-matched septic patients without delirium (non-SAD) were isolated by differential centrifugation, characterized by nanoparticle tracking analysis, transmission electron microscopy and Western blot analysis. Differential EV protein expression was determined by mass spectrometry and the resulting proteomes were characterized by Gene Ontology term and between-group statistics. As preliminary results because of the small group size, five distinct proteins showed significantly different expression pattern between SAD and non-SAD patients (p ≤ 0.05). In SAD patients, upregulated proteins included paraoxonase-1 (PON1), thrombospondin 1 (THBS1), and full fibrinogen gamma chain (FGG), whereas downregulated proteins comprised immunoglobulin (IgHV3) and complement subcomponent (C1QC). Thus, plasma EVs of SAD patients show significant changes in the expression of distinct proteins involved in immune system regulation and blood coagulation as well as in lipid metabolism in this pilot study. They might be a potential indicator for to the pathogenesis of SAD and thus warrant further examination as potential biomarkers, but further research is needed to expand on these findings in longitudinal study designs with larger samples and comprehensive polymodal data collection.

Automatic detection of venous air embolism using transesophageal echocardiography in patients undergoing neurological surgery in the semi-sitting position: a pilot study.

Neurological surgery in the semi-sitting position is linked with a pronounced incidence of venous air embolism (VAE) which can be fatal and therefore requires continuous monitoring. Transesophageal echocardiography (TEE) provides a high sensitivity for the intraoperative detection of VAE; however, continuous monitoring with TEE requires constant vigilance by the anaesthesiologist, which cannot be ensured during the entire surgical procedure. We implemented a fully automatic VAE detection system for TEE based on a statistical model of the TEE images. In the sequence of images, the cyclic heart activity is regarded as a quasi-periodic process, and air bubbles are detected as statistical outliers. The VAE detection system was evaluated by means of receiver operating characteristic (ROC) curves using a data set consisting of 155.14 h of intraoperatively recorded TEE video and a manual classification of periods with visible VAE. Our automatic detection system accomplished an area under the curve (AUC) of 0.945 if all frames with visible VAE were considered as detection target, and an AUC of 0.990 if frames with the least severe optical grade of VAE were excluded from the analysis. Offline-review of the recorded TEE videos showed that short embolic events (≤ 2 min) may be overseen when monitoring TEE video manually. Automatic detection of VAE is feasible and could provide significant support to anaesthesiologists in clinical practice. Our proposed algorithm might possibly even offer a higher sensitivity compared to manual detection. The specificity, however, requires improvement to be acceptable for practical application. Trial Registration: German Clinical Trials Register (DRKS00011607).

Cholinesterases and Anticholinergic Medications in Postoperative Pediatric Delirium.

OBJECTIVES: To describe the relationships between anticholinergic drug exposure, cholinesterase enzyme activity, inflammation, and the development of postoperative delirium in children. DESIGN: Single-center prospective cohort study. SETTING: Twenty-two bed PICU in a tertiary-care academic medical center in Germany. PATIENTS: A consecutive cohort of children admitted after major elective surgery. INTERVENTIONS: Children were screened for delirium bid over 5 consecutive postoperative days. Acetylcholinesterase and butyrylcholinesterase plasma activity levels were measured prior to surgery and once daily during the 5 day study period. Number of anticholinergic drugs and Anticholinergic Drug Scale score were calculated for each patient. MEASUREMENTS AND MAIN RESULTS: Ninety-three children (age range, 0-17 yr) were included. The number of anticholinergic drugs as well as the Anticholinergic Drug Scale score were significantly correlated with development of postoperative delirium, independently of disease severity. Baseline cholinesterase enzyme levels did not differ between patients who did and did not develop postoperative delirium. Butyrylcholinesterase levels, but not acetylcholinesterase levels, dropped by 33% postoperatively, independent of the presence of postoperative delirium. Postoperative butyrylcholinesterase levels were inversely related to number of anticholinergic drugs, Anticholinergic Drug Scale score, and C-reactive protein levels. CONCLUSIONS: Anticholinergic drug exposure was related to development of postoperative delirium in this cohort, with demonstration of a dose-response relationship. As there are alternative options available for many of these medications, it may be reasonable to avoid anticholinergic exposure in the PICU whenever possible.

Depth of anesthesia by Narcotrend® and postoperative characteristics in children undergoing cardiac surgery under extracorporeal circulation: a retrospective comparison of two anesthetic regimens.

BACKGROUND: Depth of anesthesia may be insufficient in pediatric cardiac anesthesia if a total intravenous anesthetic regimen with opioids and midazolam is used during cardiopulmonary bypass. The advantages of sevoflurane-based balanced anesthesia may be (1) a more graduated regulation of the depth of anesthesia during cardiopulmonary bypass and (2) a reduction in postoperative ventilation time for children in comparison with total intravenous anesthesia. AIM: To evaluate a possibly positive effect of sevoflurane-based balanced anesthesia in children undergoing cardiac surgery we analyzed whether this anesthetic regimen had a significant effect related to (1) depth of anesthesia, (2) the need for opioids during cardiopulmonary bypass as well as on postoperative characteristics such as (3) time of postoperative ventilation, and (4) duration of stay in the intensive care unit in comparison with total intravenous anesthesia. METHODS: In a retrospective analysis, data from heart-lung machine protocols from 2013 to 2016 were compared according to anesthetic regimen (sevoflurane-balanced anesthesia, n = 70 vs. total intravenous anesthesia, n = 65). Children (age: 8 weeks to 14 years) undergoing cardiac surgery with cardiopulmonary bypass were included. As a primary outcome measure, we compared Narcotrend® system-extracted data to detect insufficient phases of anesthetic depth during extracorporeal circulation under moderate hypothermia. Postoperatively, we measured the postoperative ventilation time and the number of days in the intensive care unit. Furthermore, we analyzed patients' specific characteristics such as opioid consumption during cardiopulmonary bypass. Regression analysis relating primary objectives was done using the following variables: anesthetic regimen, age, severity of illness/surgery, and cumulative dosage of opiates during cardiopulmonary bypass. RESULTS: No significant differences were observed in descriptive patient characteristics (age, body weight, height, and body temperature) between the two groups. Further, no significant differences were found in depth of anesthesia by analyzing phases of superficial B1-C2-electroencephalography Narcotrend® data. No marked difference between the groups was observed for the duration of postoperative intensive care unit stay. However, the postoperative ventilation time (median (95% CI, hours)) was significantly lower in the sevoflurane-based balanced anesthesia group (6.0 (2.0-15.0)) than in the total intravenous anesthesia group (13.5 (7.0-25)). A higher dosage of opioids and midazolam was required in the total intravenous anesthesia group to maintain adequate anesthesia during cardiopulmonary bypass. Regression analysis showed an additional, significant impact of the following factors: severity of illness and severity grade of cardiac surgery (according to Aristotle) on the primary endpoint. CONCLUSION: In children undergoing cardiac surgery in our department, the use of sevoflurane-balanced anesthesia during cardiopulmonary bypass showed no superiority of inhalational agents over total intravenous anesthesia with opioids and benzodiazepines preventing phases of superficial anesthesia, but a marked advantage for the postoperative ventilation time compared with total intravenous anesthesia.

Relevance of peripheral cholinesterase activity on postoperative delirium in adult surgical patients (CESARO): A prospective observational cohort study.

BACKGROUND: The cholinergic system is considered to play a key role in the development of postoperative delirium (POD), which is a common complication after surgery. OBJECTIVES: To determine whether peri-operative acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities are associated with the development of POD in in-hospital surgical patients, and raise hypotheses on cholinergic regulatory mechanisms in POD. DESIGN: A prospective multicentre observational study by the Peripheral Cholinesterase-activity on Neurocognitive Dysfunctions in Surgical Patients (CESARO) study group. SETTING: Nine German hospitals. PATIENTS: Patients of at least 18 years of age scheduled for inpatient elective surgery for a variety of surgical procedures. A total of 650 patients (mean age 61.5 years, 52.8% male) were included. METHODS: Clinical variables, and peripheral AChE and BuChE activities, were assessed throughout the peri-operative period using bedside point-of-care measurements (one pre-operative and two postoperative measurements). POD screening was conducted postoperatively for at least 24 h and up to the third postoperative day using a validated screening tool (nursing delirium screening scale). RESULTS: In all, 179 patients (27.5%) developed POD within the early postoperative phase. There was a lower BuChE activity in patients with delirium compared with patients without delirium pre-operatively (Cohen's r = 0.07, P = 0.091), on postoperative day 1 (Cohen's r = 0.12, P = 0.003) and on postoperative day 2 (Cohen's r = 0.12, P = 0.002). In contrast, there was a significantly higher AChE activity in patients with delirium compared with patients without delirium pre-operatively (Cohen's r = 0.10, P = 0.012), on postoperative day 1 (Cohen's r = 0.11, P = 0.004) and on postoperative day 2 (Cohen's r = 0.13, P = 0.002). After adjusting for covariates in multiple logistic regression, a significant association between both BuChE and AChE activities and POD was not found. However, in the multivariable analysis using the Generalized Estimating Equation, cholinesterase activities showed that a decrease of BuChE activity by 100 U L increased the risk of a delirium by approximately 2.1% (95% CI 1.6 to 2.8%) and for each 1 U g of haemoglobin increase in AChE activity, there was a 1.4% (95% CI 0.6 to 2.2%) increased risk of POD. CONCLUSION: Peri-operative peripheral cholinesterase activities may be related to the development of POD, but the clinical implications remain unclear. Further studies, in homogeneous patient groups with a strict protocol for measurement time points, are needed to investigate the relationship between cholinesterase activities and POD. TRIAL REGISTRATION: www.clinicaltrials.gov. Identifier NCT01964274.

In-depth characterization of the neuroinflammatory reaction induced by peripheral surgery in an animal model.

Delirium is a common complication seen after surgery and anesthesia, in particular in older patients. Although the etiology of postoperative delirium is only incompletely understood, various lines of evidence suggest that proinflammatory signaling from the peripheral site of inflammation to central nervous system results in a decrease of cerebral acetylcholine (ACh) levels thereby inducing neuroinflammation. To corroborate this theory, we applied an animal model for characterization of the neuroinflammatory response after partial hepatectomy (HPx). In this model, the surgery-induced decrease in cerebral ACh levels can be prevented by intraoperative application of physostigmine. Thus, ACh-associated changes in the expression and secretion of inflammation-related compounds can be assessed by comparing the results obtained after surgery, in physostigmine-treated and untreated controls. This way we were able to show that the decrease of cerebral ACh triggers increased secretion of IL-1ß, IL-6, TNFα, MIP-2 (CCL3), RANTES, MCP1, IFNgamma, and IP-10. A gene array covering the expression of 370 inflammation-related genes indicated 13 candidates that are induced upon cerebral ACh decrease after HPx. Quantification of the changes in the expression of these candidates by the comparative CT method revealed a significant increase (> 1.5-fold) in the expression of IL-1ß, IL-6, TNFα, MIP2, RANTES, MCP1, TLR2, TLR4, HMGB1, TNFSF6, TNFSF12, IL1R1 and ILR6. Thus, our results suggest that peripheral surgery induces a reduction of cerebral ACh levels which trigger a complex neuroinflammatory response. From a clinical point of view, manipulating cerebral ACh levels by procholinergic drugs such as physostigmine could become an option to therapeutically target this kind of neuroinflammation.

Ablation of the Right Cardiac Vagus Nerve Reduces Acetylcholine Content without Changing the Inflammatory Response during Endotoxemia.

Acetylcholine is the main transmitter of the parasympathetic vagus nerve. According to the cholinergic anti-inflammatory pathway (CAP) concept, acetylcholine has been shown to be important for signal transmission within the immune system and also for a variety of other functions throughout the organism. The spleen is thought to play an important role in regulating the CAP. In contrast, the existence of a "non-neuronal cardiac cholinergic system" that influences cardiac innervation during inflammation has been hypothesized, with recent publications introducing the heart instead of the spleen as a possible interface between the immune and nervous systems. To prove this hypothesis, we investigated whether selectively disrupting vagal stimulation of the right ventricle plays an important role in rat CAP regulation during endotoxemia. We performed a selective resection of the right cardiac branch of the Nervus vagus (VGX) with a corresponding sham resection in vehicle-injected and endotoxemic rats. Rats were injected with lipopolysaccharide (LPS, 1 mg/kg body weight, intravenously) and observed for 4 h. Intraoperative blood gas analysis was performed, and hemodynamic parameters were assessed using a left ventricular pressure-volume catheter. Rat hearts and blood were collected, and the expression and concentration of proinflammatory cytokines using quantitative reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay were measured, respectively. Four hours after injection, LPS induced a marked deterioration in rat blood gas parameters such as pH value, potassium, base excess, glucose, and lactate. The mean arterial blood pressure and the end-diastolic volume had decreased significantly. Further, significant increases in blood cholinesterases and in proinflammatory (IL-1ß, IL-6, TNF-α) cytokine concentration and gene expression were obtained. Right cardiac vagus nerve resection (VGX) led to a marked decrease in heart acetylcholine concentration and an increase in cardiac acetylcholinesterase activity. Without LPS, VGX changed rat hemodynamic parameters, including heart frequency, cardiac output, and end-diastolic volume. In contrast, VGX during endotoxemia did not significantly change the concentration and expression of proinflammatory cytokines in the heart. In conclusion we demonstrate that right cardiac vagal innervation regulates cardiac acetylcholine content but neither improves nor worsens systemic inflammation.

Role of ultrasound measuring position and ventilation pressure in determining correct tube size in children.

BACKGROUND: Ultrasound measurements of the airway are useful for determining correctly sized, uncuffed endotracheal tubes in children. AIMS: The primary objective of this study was to evaluate the influence of ventilation pressure on the sonographically measured tracheal diameter at different levels. METHODS: A total of 100 patients (under 7 years) were enrolled in this study. Six sonographic measurements of minimal transverse diameters at 3 locations (vocal chords, cricoid cartilage, and proximal trachea) and at 2 different ventilation pressures (0 and 15 mbar) were performed before the intubation procedure. The intubating anesthesiologists were blinded to the results of the ultrasound measurements. The rate of agreement of the outer diameter of the correctly sized endotracheal tube (reference) with the 6 sonographic diameters was determined. In addition, the correct tube sizes were compared with the results of traditional prediction methods (Penlington's and Cole's formula in children ≥1 year and a decision table in children <1 year). RESULTS: Best rate of agreement resulted from cricoid cartilage (70% and 83% at 0 and 15 mbar). CONCLUSION: The airway level selected for ultrasound and airway pressure during measurement determines the rate of agreement between the measurement result and correct ETT size.

Limitations of the Anticholinergic Activity Assay and Assay-Based Anticholinergic Drug Scales.

OBJECTIVE: The anticholinergic activity (AA) assay is a common method to determine a patient's anticholinergic load. Several limitations, however, are expected when applying the AA assay to patients or using drug scales to estimate anticholinergic burden based on AA levels. This study aims to demonstrate common pitfalls in an experimental setting and outline their clinical consequences. METHODS: The AA was analyzed for five drugs with reported interaction with muscarinic receptors. Concentration-response curves were constructed for furosemide (weak anticholinergic), diphenhydramine (moderate anticholinergic), the strong anticholinergic amitriptyline and its metabolite nortriptyline, and the cholinergic pilocarpine. The Combination Index (CI) was used to assess the interaction of three drug combinations with amitriptyline. RESULTS: All compounds displaced the radioactive tracer from its receptor binding site in a concentration-dependent manner, and full displacement was reached for all compounds except furosemide (Emax 16%). The CI indicated that amitriptyline and thioridazine have antagonistic effects (CI = 1.46) at low and synergistic effects (CI = 0.88) at higher concentrations (p < 0.0001), whereas synergistic effects (CI = 0.47-0.48) were observed for amitriptyline in any concentration combined with pilocarpine (p < 0.001). CONCLUSION: When the patient's anticholinergic load is estimated using AA levels, the actual exposure, combination of anticholinergic drugs, their active metabolites, and also drugs with an opposite pharmacologic action will contribute to AA levels, whereas weak anticholinergic drugs in therapeutic concentrations are rather negligible.

In vitro streptozotocin model for modeling Alzheimer-like changes: effect on amyloid precursor protein secretases and glycogen synthase kinase-3.

There is accumulating evidence for a pathogenetic link between sporadic Alzheimer's disease (AD) and diabetes mellitus (DM). At subdiabetogenic doses, the cerebral administration of the diabetogenic substance streptozotocin (STZ) induces an insulin-resistant brain state (IRBS). The aim of the present pilot study was to investigate the effect of STZ on Alzheimer-like characteristics such as amyloid precursor protein (APP) cleavage secretases, betaA4 fragment, and glycogen synthase kinase (GSK) in vitro. Different STZ concentrations (0-5 mM) and incubation intervals (0-48 h) were tested to find appropriate cell culture conditions for further biochemical analyses in human neuroblastoma cells (SK-N-MC). Lactate dehydrogenase (LDH) was measured spectrophotometrically. Intracellular ATP was determined using bioluminescent luciferase assay. Secretase activity (alpha, beta, and gamma) was measured by employing commercial fluorometric secretase activity assay kits, betaA4 fragment by immunoprecipitation. Glycogen synthase kinase-3alpha/beta (total and phospho-GSK) content was assayed by ELISA technique. In vitro STZ administration (1 mM) induced a significant reduction in intracellular ATP concentration without pronounced cell death after 24 and 48 h as measured by LDH. Under these experimental conditions, a significant increase in beta-secretase and a significant drop in alpha-secretase were obtained, whereas gamma-secretase was not changed significantly. Simultaneously, the betaA4 concentration was increased by about threefold. Furthermore, STZ significantly increased total GSK and markedly decreased phospho-GSK. A direct link between STZ, intracellular ATP deficit, and Alzheimer-related enzymes was shown in this in vitro pilot study. Thus, these results support the hypothesis that sporadic AD is being recognized as an IRBS, which can be modulated by in vitro STZ model. Continuing investigations relating pathogenetic mechanisms and AD-like hallmarks are necessary to modulate different cascades of the IRBS using in vitro models.

Surgery-induced changes in rat IL-1ß and acetylcholine metabolism: role of physostigmine.

Pharmacological enhancement of cholinergic activity following administration of physostigmine is known to induce protective effects generally. However, it is unclear whether the effect of physostigmine on inflammation and acetylcholine (ACh) metabolism is related to different types of surgical intervention or anaesthesia alone. To investigate this, rats were subjected to partial liver resection (PLR) or sham surgery, with a control group receiving anaesthesia alone. Half of each treatment group received a single intra-operative dose of physostigmine (0.04 mg/kg); the others received placebo. Acetylcholinesterase (AChE) activity and plasma and brain concentrations of interleukin (IL)-1ß and ACh were determined. Both PLR and sham operation induced a time-dependent increase in plasma concentrations of IL-1ß compared with rats receiving anaesthesia alone (3.9- and 4.8-fold increases, respectively). In the brain, IL-1ß concentrations had increased approximately twofold after surgery compared with the control group. Blood AChE was transiently decreased after surgery. Brain AChE activity increased 1.3-fold (P = 0.014) only after PLR; consequently, cerebral ACh concentrations were significantly reduced. Physostigmine administration significantly reduced IL-1ß and AChE levels. Cerebral ACh concentrations were markedly increased from 544 ± 122 ng/mg protein following placebo administration to 654 ± 93 ng/mg protein after physostigmine administrations (P < 0.001). We conclude that a single dose of physostigmine intra-operatively has a sustained anti-inflammatory effect (up to 120 min after injection) that is especially pronounced under the conditions of PLR surgery. In addition to its protective peripheral action, physostigmine exerts a neuroprotective action by increasing levels of the neurotransmitter ACh.

Development and Pilot Testing of an Algorithm-Based Approach to Anticholinergic Deprescribing in Older Patients.

BACKGROUND: Adverse anticholinergic drug reactions are common, yet evidence on how to reduce exposure to anticholinergic activity and reliably measure successful deprescribing is still scant. This study proposes an algorithm-based approach to evaluate and reduce anticholinergic load, and reports the results of its pilot testing. METHODS: Based on published evidence and expert opinion, a list of 85 anticholinergic drugs and 21 algorithms for reducing anticholinergic load, e.g., by recommending alternative drugs with lower risk, were developed. An accompanying test battery was assembled by focusing on instruments that sensitively reflect anticholinergic load and may be sensitive to depict changes (Neuropsychological Assessment Battery to measure memory and attention, validated assessments for constipation, urinary symptoms, and xerostomia, as well as blood biomarkers). The approach was pilot-tested in a geriatric rehabilitation unit, with clinician feedback as the primary outcome and characterization of anticholinergic symptoms as the secondary outcome. The intervention was delivered by a pharmacist and a clinical pharmacologist who used the algorithms to generate personalized recommendation letters. RESULTS: We included a total of 20 patients, 13 with anticholinergic drugs and 7 without. Recommendations were made for 22 drugs in nine patients from the intervention group, of which seven letters (78%) were considered helpful and 8/22 (36%) anticholinergic drugs were discontinued, reducing anticholinergic load in seven patients. In contrast to patients without drug change, memory assessment in patients with reduced anticholinergic load improved significantly after 2 weeks (6 ± 3 vs. -1 ± 6 points). CONCLUSIONS: The approach was well received by the participating physicians and might support standardized anticholinergic deprescribing.

The accuracy and responsiveness of continuous noninvasive arterial pressure during rapid ventricular pacing for transcatheter aortic valve replacement.

BACKGROUND: The accuracy of measurement of the continuous noninvasive arterial blood pressure (CNAP) technique is unknown during sudden cardiocirculatory arrest. METHODS: In 33 patients undergoing elective transfemoral aortic valve implantation procedures under analgesic sedation, invasive arterial blood pressure (IAP) was compared with a CNAP device during episodes of severe hypotension (functional cardiocirculatory arrests by rapid pacing) and the remaining time without severe hypotension. Systolic, diastolic, and mean pairs of blood pressure measurements were extracted for both groups and were analyzed by Bland-Altman plots. The responsiveness of the CNAP technique was assessed in the various phases of severe hypotension concerning time and amplitude of changes. RESULTS: Overall CNAP accuracy (bias), calculated by subtracting IAP from CNAP, was -6.3 ± 18.9, 7.4 ± 10.5, and 4.0 ± 11.3 mm Hg (mean ± SD, systolic, diastolic, and mean). Bias increased during episodes of severe hypotension to 11.8 ± 14.5, 13.8 ± 12.4, and 12.9 ± 12.4 mm Hg. The percentage of agreements (95% confidence interval) between the blood pressure pairs with a difference ≤15 mm Hg was 58.5% (57.9-58.6), 75.8% (75.5-76.0), 82.2% (81.9-82.4; systolic, diastolic, mean) for all data and 56.4% (54.2-58.9; P = 0.71), 53.2%* (51.1-56.0), and 57.4%* (56.3-59.1; *P < 0.001) during rapid pacing. The responsiveness of mean CNAP and mean IAP did not differ significantly during the various phases of rapid pacing. CONCLUSIONS: The stand-alone CNAP monitor (model 500at, software V3.5) accurately and rapidly measures the changes of blood pressure that occur during sudden development of cardiocirculatory arrest and recovery to baseline blood pressures. CNAP monitors the duration of the arrest.

Levosimendan's effect on platelet function in a rat sepsis model.

Although studies have evaluated the efficacy of levosimendan in heart failure during sepsis, it still is a subject of controversy whether levosimendan produces an effect on platelets. In this study, the short- and long-term effects of levosimendan on platelet aggregation were investigated in untreated animals and in a rat model of sepsis. Therefore, adult rats (n = 40) were randomly divided into four groups with n = 10 per group: (I) sham, (II) levosimendan (bolus 53 µg/kg + 285 µg/kg/hour, intravenously (i.v.) injected), (III) LPS (lipopolysaccharide, 8 mg/kg body weight intraperitoneally injected), and (IV) LPS + levosimendan. Levosimendan was given 24 hours after LPS injections. The number of platelets was determined. Platelet aggregation was measured using venous blood from rats 10 minutes and 5 days after levosimendan application with Dynabyte Multiplate system. Aggregation responses were evaluated with adenosine diphosphate (10 µM) and collagen (5 µg/ml). In addition to clinical dosage, the in vitro effect of high-dosage levosimendan on platelet function was investigated. The results clearly showed that LPS significantly reduced the platelet aggregation 1 day after injection compared to controls; 6 days after LPS, a marked increase (p < 0.01) was noted. This result is associated with numbers of platelets. Levosimendan (bolus 53 µg/kg + 285 µg/kg/hour i.v.) had no significant effect on the platelets of rats in contrast to the high-dosage in vitro findings. Thus, the in vivo use of levosimendan does not affect blood coagulation significantly in this rat model. This also applies under the conditions of decreased and increased numbers of platelets during mild sepsis.

Role of ultrasound compared to age-related formulas for uncuffed endotracheal intubation in a pediatric population.

BACKGROUND: It is often difficult to determine the correct size of endotracheal tubes (ETT) needed for intubating pediatric patients. Therefore, we evaluated the role of ultrasound in pediatric patients to compare the correct size of an uncuffed (ETT) with the minimal transverse diameter of the subglottic airway (MTDSA) measured by ultrasound and with tube size predicted by different age-related formulas. METHODS: A total of 50 pediatric patients ≤ 5 years were enrolled. As a standard, we defined the adequate ETT size with no audible leakage below a ventilation pressure of 15 mbar and with an audible leakage above 25 mbar. The maximum allowed difference between the prediction method result and the ETT that fit was defined as 0.3 mm. Ultrasound was performed before the intubation procedure; the intubating anesthesiologists were blinded to the results of the ultrasound measurement. Agreement between the two age-based formulas most commonly used at our department and MTDSA with the correct ETT size (standard) was analyzed using a Bland-Altman plot. Correlation and regression analyses were performed and the numbers of correct intubation trials recorded. RESULTS: The frequency of bias ≤ 0.3 mm between each method and the correct ETT in the first attempt was <50% and the mean number of reintubations 1.6 ± 1.3. In contrast to age-related formulas, however, the ultrasonographically determined MTDSA was not significantly different from the correct ETT. MTDSA was highly associated with the outer diameter of the ETT (r = 0.869, R(2) = 0.754). CONCLUSIONS: Measuring MTDSA by ultrasound facilitates selection of the appropriate ETT in pediatric patients and may reduce the number of reintubations.

Ginkgo extract EGb 761(®) shields from slowly accumulating neurodegenerative-like changes in a newly developed cell culture model induced by the combined action of low doses of antimycin A1 and 2-deoxy-D-glucose.

Different cell culture models were already used to analyze the molecular base of the neuroprotective activities of the Ginkgo biloba extract EGb 761(®) after a single or short-term application. In these previous studies cells were severely injured with agents that promptly induce fatal cellular damage, like vast oxidative stress or mitochondrial dysfunction, and the protective effects of EGb 761(®) on such acute damage were evaluated. Our present study aimed to test EGb 761(®) action in cell cultures, where cellular functions are only moderately impaired by a longer lasting, but relatively modest oxidative stress, reduction of mitochondrial function and reduced intracellular energy levels, thereby causing only slow occurence of cellular damage over a time period of 2 weeks. To this end we used neuroblastoma cells (SK-N-MC) that were treated with low doses of a combination of antimycin A1 and 2-deoxy-D: -glucose. Addition of EGb 761(®) to the culture medium efficiently shielded the cells from progressing injury by reduced ATP-levels, oxidized redox state, lipid peroxidation damage and oxidative damage of mitochondrial DNA. As a result the cells were protected from apoptotic death that was observed in cultures without EGb 761(®) after 2 weeks of damage occurence. This cell culture system characterizing moderate cellular stress will be applied in future studies to further investigate the mode of action of single EGb 761(®) compounds.

Chronic exogenous corticosterone administration generates an insulin-resistant brain state in rats.

We investigated whether long-term administration of exogenous corticosterone (CST) or vehicle as daily treatment induces changes in rat behavior and in gene expression of the rat brain insulin signaling pathway and the formation of tau protein. Two groups of male adult rats received daily subcutaneous injections of 26.8 mg/kg CST (CST stress group) or vehicle-sesame oil (injection stress group) for 60 days while the third group was taken as untreated controls (n = 8 each). Body weight and plasma CST were measured and psychometric investigations were conducted using a rat holeboard test system before and after the treatment. Gene expression analyzes were performed by RT-PCR in cerebral cortical tissue for insulin genes 1 and 2, insulin receptor (IR), insulin degrading enzyme (IDE), and tau protein. Daily injections of CST for 60 days induced a significant, 2-fold increase in rat plasma CST concentrations in comparison to untreated controls. Significantly reduced behavioral abilities in CST-treated rats were associated with reduced gene expression of insulin 1 ( - 20%), IDE ( - 23%), and IR ( - 26%), indicating an insulin-resistant brain state, followed by increased tau protein (+28%) gene expression. In summary, chronic CST administration affects gene expression in the brain IR signaling cascade and increases tau gene expression, which is associated with reductions in cognition capacity in rats.

Insulin-resistant brain state (IRBS) changes membrane composition of fatty acids in temporal and entorhinal brain cortices of rats: relevance to sporadic Alzheimer's disease?

An insulin-resistant brain state (IRBS) was induced by intracerebroventricular application of the diabetogenic substance streptozotocin (STZ) to investigate changes in cerebral fatty acids. Six weeks after the first STZ injection, increases were found in the concentrations of palmitic and stearic acid in temporal cortex; and of palmitic acid in entorhinal cortex indicative of membrane phospholipid breakdown, and damage of the membrane structure. The relevance of these changes is discussed in relation to sporadic Alzheimer's disease.

A subchronic application period of glucocorticoids leads to rat cognitive dysfunction whereas physostigmine induces a mild neuroprotection.

The cholinergic neurotransmitter system and prolonged glucocorticoid-induced stress can affect cognitive functions in opposite ways. While pharmacological enhancement of cholinergic neurotransmission is known to induce neuroprotective effects, chronic glucocorticoids impair cognitive functions. Up to now, there is no consensus as to whether a subchronic stress period of several days would affect cognitive function. The goal of this study was to investigate whether or not repeated applications of physostigmine over 3 days lead to protective effects on rat spatial cognitive abilities in contrast to the deteriorating effect on rat cognitive function after corticosterone treatment. Furthermore, we wanted to investigate in what extent this cognition-modulating effect is associated with rat cerebral acetylcholinergic system. Male adult rats (n = 40) were randomly divided into four groups with n = 10 per group: (I) placebo-, (II) corticosterone- (15 mg/day), (III) physostigmine- (0.014 mg/day), and (IV) physostigmine + corticosterone-treated rats. Body mass and plasma corticosterone concentrations were measured. Psychometric investigations were conducted using a Morris water maze before and after a subchronic treatment. In cerebral tissue, ACh and acetylcholinesterase (AChE) content and ACh receptor density were determined. Tissue corticosterone concentration was measured in cerebral cortex, hippocampus, and adrenal glands. In corticosterone-treated rats, reduced spatial cognitive abilities were associated with a significant increase in plasma (+25%) and cerebral corticosterone levels (+350%) parallelled by a significant reduction in adrenal gland concentrations (-84%) as compared to placebo. Repeated physostigmine injections improved rats' spatial memory and increased cerebral ACh and AChE content (p < 0.05). When physostigmine was administered at the same time as corticosterone (group IV), it was not able to reverse the corticosterone effect. A significant correlation was detected between cerebral AChE and corticosterone concentrations as well as between AChE and psychometric parameters. We conclude that subchronic exogenous corticosterone administration induces memory dysfunction whereas physostigmine exerts cognitive-enhancing effects if given for 3 days. An apparently existing interaction between glucocorticoid excess and ACh metabolism is discussed.