Common mechanisms of auditory hallucinations-perfusion studies in epilepsy

Auditory hallucinations (AH) occur in various neurological and psychiatric disorders. In psychosis, increased neuronal activity in the primary auditory cortex (PAC) contributes to AH. We investigated functional neuroanatomy of epileptic hallucinations by measuring cerebral perfusion in three patients with AH during simple partial status epilepticus. Hyperperfusion in the temporal lobe covering the PAC occurred in all patients. Our perfusion data support the hypothesis of PAC being a constituting element in the genesis of AH independent of their aetiology.

Antegrade selective cerebral perfusion and moderate hypothermia in aortic arch surgery: clinical outcomes in elderly patients

To evaluate the outcome in elderly patients (≥ 75 years) undergoing elective aortic arch surgery with the aid of selective antegrade cerebral perfusion (SACP) and moderate hypothermic circulatory arrest (HCA).

Quantification of network perfusion in ASL cerebral blood flow data with seed based and ICA approaches

Independent component analysis (ICA) or seed based approaches (SBA) in functional magnetic resonance imaging blood oxygenation level dependent (BOLD) data became widely applied tools to identify functionally connected, large scale brain networks. Differences between task conditions as well as specific alterations of the networks in patients as compared to healthy controls were reported. However, BOLD lacks the possibility of quantifying absolute network metabolic activity, which is of particular interest in the case of pathological alterations. In contrast, arterial spin labeling (ASL) techniques allow quantifying absolute cerebral blood flow (CBF) in rest and in task-related conditions. In this study, we explored the ability of identifying networks in ASL data using ICA and to quantify network activity in terms of absolute CBF values. Moreover, we compared the results to SBA and performed a test-retest analysis. Twelve healthy young subjects performed a fingertapping block-design experiment. During the task pseudo-continuous ASL was measured. After CBF quantification the individual datasets were concatenated and subjected to the ICA algorithm. ICA proved capable to identify the somato-motor and the default mode network. Moreover, absolute network CBF within the separate networks during either condition could be quantified. We could demonstrate that using ICA and SBA functional connectivity analysis is feasible and robust in ASL-CBF data. CBF functional connectivity is a novel approach that opens a new strategy to evaluate differences of network activity in terms of absolute network CBF and thus allows quantifying inter-individual differences in the resting state and task-related activations and deactivations.

Ischemia/reperfusion injury of porcine limbs after extracorporeal perfusion

Revascularization of amputated extremities after prolonged ischemia is complicated by reperfusion injury. We assessed ischemia/reperfusion (I/R) injury of porcine extremities after prolonged preservation using extracorporeal circulation (ECC).

Renal perfusion evaluation with contrast-enhanced ultrasonography

Contrast-enhanced ultrasonography (CEUS) is a novel imaging technique that is safe and applicable on the bedside. Recent developments seem to enable CEUS to quantify organ perfusion. We performed an exploratory study to determine the ability of CEUS to detect changes in renal perfusion and to correlate them with effective renal plasma flow.

Post-mortem angiography after vascular perfusion with diesel oil and a lipophilic contrast agent

OBJECTIVE: The objective of our study was to establish optimal perfusion conditions for high-resolution postmortem angiography that would permit dynamic visualization of the arterial and venous systems. MATERIALS AND METHODS: Cadavers of two dogs and one cat were perfused with diesel oil through a peristaltic pump. The lipophilic contrast agent Lipiodol Ultra Fluide was then injected, and angiography was performed. The efficiency of perfusion was evaluated in the chick chorioallantoic membrane. RESULTS: Vessels could be seen up to the level of the smaller supplying and draining vessels. Hence, both the arterial and the venous sides of the vascular system could be distinguished. The chorioallantoic membrane assay revealed that diesel oil enters microvessels up to 50 microm in diameter and that it does not penetrate the capillary network. CONCLUSION: After establishing a postmortem circulation by diesel oil perfusion, angiography can be performed by injection of Lipiodol Ultra Fluide. The resolution of the images obtained up to 3 days after death is comparable to that achieved in clinical angiography.

Detection of regional blood perfusion changes in epileptic seizures with dynamic brain perfusion CT--a pilot study

BACKGROUND AND PURPOSE: Perfusion CT (P-CT) is used for acute stroke management, not, however, for evaluating epilepsy. To test the hypothesis that P-CT may identify patients with increased regional cerebral blood flow during subtle status epilepticus (SSE), we compared P-CT in SSE to different postictal conditions. METHODS: Fifteen patients (mean age 47 years, range 21-74) underwent P-CT immediately after evaluation in our emergency room. Asymmetry indices between affected and unaffected hemispheres were calculated for regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and mean transit time (MTT). Regional perfusion changes were compared to EEG findings. RESULTS: Three patients in subtle status epilepticus (group 1) had increased regional perfusion with electro-clinical correlate. Six patients showed postictal slowing on EEG corresponding to an area of regional hypoperfusion (group 2). CT and EEG were normal in six patients with a first epileptic seizure (group 3). Cluster analysis of asymmetry indices separated SSE from the other two groups in all three parameters, while rCBF helped to distinguish between chronic focal epilepsies and single events. CONCLUSION: Preliminary results indicate that P-CT may help to identify patients with SSE during emergency workup. This technique provides important information to neurologists or emergency physicians in the difficult clinical differential diagnosis of altered mental status due to subtle status epilepticus.

Decreasing gut wall glucose as an early marker of impaired intestinal perfusion

OBJECTIVE: The aim of this study was to assess the microcirculatory and metabolic consequences of reduced mesenteric blood flow. DESIGN: Prospective, controlled animal study. SETTING: The surgical research unit of a university hospital. SUBJECTS: A total of 13 anesthetized and mechanically ventilated pigs. INTERVENTIONS: Pigs were subjected to stepwise mesenteric blood flow reduction (15% in each step, n = 8) or served as controls (n = 5). Superior mesenteric arterial blood flow was measured with ultrasonic transit time flowmetry, and mucosal and muscularis microcirculatory perfusion in the small bowel were each measured with three laser Doppler flow probes. Small-bowel intramucosal Pco2 was measured by tonometry, and glucose, lactate (L), and pyruvate (P) were measured by microdialysis. MEASUREMENTS AND MAIN RESULTS: In control animals, superior mesenteric arterial blood flow, mucosal microcirculatory blood flow, intramucosal Pco2, and the lactate/pyruvate ratio remained unchanged. In both groups, mucosal blood flow was better preserved than muscularis blood flow. During stepwise mesenteric blood flow reduction, heterogeneous microcirculatory blood flow remained a prominent feature (coefficient of variation, approximately 45%). A 30% flow reduction from baseline was associated with a decrease in microdialysis glucose concentration from 2.37 (2.10-2.70) mmol/L to 0.57 (0.22-1.60) mmol/L (p < .05). After 75% flow reduction, the microdialysis lactate/pyruvate ratio increased from 8.6 (8.0-14.1) to 27.6 (15.5-37.4, p < .05), and arterial-intramucosal Pco2 gradients increased from 1.3 (0.4-3.5) kPa to 10.8 (8.0-16.0) kPa (p < .05). CONCLUSIONS: Blood flow redistribution and heterogeneous microcirculatory perfusion can explain apparently maintained regional oxidative metabolism during mesenteric hypoperfusion, despite local signs of anaerobic metabolism. Early decreasing glucose concentrations suggest that substrate supply may become crucial before oxygen consumption decreases.

Arterio-venous gradients of free energy change for assessment of systemic and splanchnic perfusion in cardiac surgery patients

OBJECTIVE: Adequacy of organ perfusion depends on sufficient oxygen supply in relation to the metabolic needs. The aim of this study was to evaluate the relationship between gradients of free energy change, and the more commonly used parameter for the evaluation of the adequacy of organ perfusion, such as oxygen-extraction in patients undergoing valve replacement surgery using normothermic cardiopulmonary bypass (CPB). METHODS: In 43 cardiac patients, arterial, mixed venous, and hepato-venous blood samples were taken synchronously after induction of anaesthesia (preCPB), during CPB, and 2 and 7 h after admission to the intensive care unit (ICU+2, ICU+7). Blood gas analysis, cardiac output, and hepato-splanchnic blood flow were measured. Free energy change gradients between mixed venous and arterial (-deltadeltaG(v - a)) and hepato-venous and arterial (-deltadeltaG(hv - a)) compartments were calculated. MEASUREMENTS AND RESULTS: Cardiac index (CI) increased from 1.9 (0.7) to 2.8 (1.3) L/min/m (median, inter-quartile range) (p = 0.001), and hepato-splanchnic blood flow index (HBFI) from 0.6 (0.22) to 0.8 (0.53) L/min/m (p = 0.001). Despite increasing flow, systemic oxygen extraction increased after CPB from 24 (10)% to 35 (10)% at ICU+2 (p = 0.002), and splanchnic oxygen extraction increased during CPB from 37 (19)% to 52 (14)% (p = 0.001), and remained high thereafter. After CPB, high splanchnic and systemic gradients of free energy change gradients were associated with high splanchnic and systemic oxygen extraction, respectively (p = 0.001, 0.033, respectively). CONCLUSION: Gradients of free energy change may be helpful in characterising adequacy of perfusion in cardiac surgery patients independently from measurements or calculations of data from oxygen transport.

A comparative study of water perfusion catheters and microtip transducer catheters for urethral pressure measurements

The aim of this study was to compare the maximum urethral closure pressure (MUCP) measures with two different techniques: water perfused catheter and microtip transducer catheters with respect to reproducibility and comparability for urethral pressure measurements. Eighteen women with stress urinary incontinence had repeat static urethral pressure profilometry on a different day using a dual microtip transducer and water perfused catheter (Brown and Wickham). The investigators were blinded to the results of the other. The microtip measurements were taken in the 45 degrees upright sitting position with the patient at rest at a bladder capacity of 250 ml using an 8 Fr Gaeltec(R) double microtip transducer withdrawn at 1 mm/s, and the transducer was orientated in the three o'clock position. Three different measures were taken for each patient. Three water perfusion measurements were performed with the patient at rest in the 45 degrees upright position at a bladder capacity of 250 ml using an 8 Fr BARD dual lumen catheter withdrawn at 1 mm/s. The mean water perfusion MUCP measure was 26.1 cm H(2)0, significantly lower than the mean microtip measure of 35.7 cm H(2)0. The correlation coefficient comparing each water perfusion measurement with the other water perfusion measures in the same patient was excellent, at 0.95 (p = 0.01). Correlation coefficient comparing each microtip measure with the other microtip measure in the same patient was also good, ranging from 0.70 to 0.80. This study confirms that both water perfusion catheters and microtip transducers have excellent or very good reproducibility with an acceptable intraindividual variation for both methods.

Dual in vitro perfusion of an isolated cotyledon as a model to study the implication of changes in the third trimester placenta on preeclampsia

In the current study perfusions of an isolated cotyledon of term placenta using standard medium were compared to medium containing xanthine plus xanthine oxidase (X+XO), which generates reactive oxygen species (ROS). A time-dependant increase in the levels of different cytokines (TNF-alpha, IL-1ss, IL-6, IL-8 and IL-10) was observed between 1 and 7h with more than 90% of the total recovered from the maternal compartment with no significant difference between the 2 groups. For 8-iso-PGF2alpha 90% of the total was found in the fetal compartment and a significantly higher total release was seen in the X+XO group. Microparticles (MPs) isolated from the maternal circuit were identified by flow cytometry as trophoblastic sheddings, whereas MPs from the fetal circuit were predominantly derived from endothelial cells. More than 90% of the total of MPs was found in the maternal circuit. The absolute amount of the total as well as the maternal fraction were significantly higher in the X+XO group. Immunohistochemistry (IHC) of the perfused tissue revealed staining for IL-1beta of villous stroma cells, which became clearly more pronounced in experiments with X+XO. Western blot of tissue homogenate revealed 2 isoforms of IL-1beta at 17 and 31kD. In X+XO experiments there was a tendency for increased expression of antioxidant enzymes in the tissue. Western blot of MPs from the maternal circuit showed increased expression of antioxidant enzymes in the X+XO group and for IL-1beta only the 17kD band was detected. In vitro reperfusion of human placental tissue results in mild tissue injury suggestive of oxidative stress. In view of the increased generation of ROS in perfused tissue with further increase under the influence of X+XO, the overall manifestation of oxidative stress remained rather mild. Preservation of antioxidant capacity of human placental tissue could be a sign of integrity of structure and function being maintained in vitro by dual perfusion of an isolated cotyledon. The observed changes resemble findings seen in placentae from preeclampsia.

Differential release of plasminogen activator inhibitors (PAIs) during dual perfusion of human placenta: implications in preeclampsia

Plasminogen activator inhibitors (PAIs) play critical roles in regulating cellular invasion and fibrinolysis. An increase in the ratio of PAI-1/PAI-2 in placenta and maternal serum is suggested to result in excessive intervillous fibrin deposition and placental infarction in pregnancies complicated by preeclampsia (PE) and intrauterine growth restriction (IUGR). In the current study we used dual (maternal and fetal) perfusion of human term placentas to examine the release of PAIs to the intervillous space. ELISA revealed a significant time-dependent increase in total PAI-1 levels in maternal perfusate (MP) between 1 and 7h of perfusion. Conversely, PAI-2 levels decreased resulting in a 3-fold increase in the PAI-1/PAI-2 ratio in MP. Levels of PAI-1, but not PAI-2, in placental tissue extracts increased during perfusion. In perfusions carried out with xanthine and xanthine oxidase (X + XO), compounds used to generate reactive oxygen species (ROS), no time-dependent increase in total PAI-1 levels was observed. In addition, X + XO treatment promoted a 3-fold reduction in active PAI-1 levels in MP, indicating that ROS decrease PAI-1 release to MP. The finding of a time-dependent change in patterns of PAI expression and response to ROS indicates the utility of dual perfusion as a model to dissect mechanism(s) promoting aberrant fibrinolysis in pregnancies complicated by PE and IUGR.