Clinical Implication of Phosphodiesterase-4-Inhibition.

The pleiotropic function of 3',5'-cyclic adenosine monophosphate (cAMP)-dependent pathways in health and disease led to the development of pharmacological phosphodiesterase inhibitors (PDE-I) to attenuate cAMP degradation. While there are many isotypes of PDE, a predominant role of PDE4 is to regulate fundamental functions, including endothelial and epithelial barrier stability, modulation of inflammatory responses and cognitive and/or mood functions. This makes the use of PDE4-I an interesting tool for various therapeutic approaches. However, due to the presence of PDE4 in many tissues, there is a significant danger for serious side effects. Based on this, the aim of this review is to provide a comprehensive overview of the approaches and effects of PDE4-I for different therapeutic applications. In summary, despite many obstacles to use of PDE4-I for different therapeutic approaches, the current data warrant future research to utilize the therapeutic potential of phosphodiesterase 4 inhibition.

[Sectio Caesarea under Gitelman Syndrome]. / Sectio caesarea unter Gitelman-Syndrom.

Gitelman syndrome is a rare inherited renal tubulopathy characterized by hypokalemia, hypomagnesemia and metabolic alcalosis. It is caused by a mutation in the SLC12A3 gene leading to a dysfunction of the thiazide-sensitive sodium chloride cotransporter and the magnesium transporters in the distal convoluted tubules. Only few reports of pregnant woman with Gitelman syndrome exist. Due to many unsolved questions about the impact on pregnancy and the maternal and fetal outcome, the obstetric and anesthesiological management remains a challenge. We discuss the case of a primary cesarean delivery in a 22-year-old woman with a new diagnosed Gitelman syndrome focusing on the anesthesiological approach.

Carbon Monoxide Exerts Functional Neuroprotection After Cardiac Arrest Using Extracorporeal Resuscitation in Pigs.

OBJECTIVES: Neurologic damage following cardiac arrest remains a major burden for modern resuscitation medicine. Cardiopulmonary resuscitation with extracorporeal circulatory support holds the potential to reduce morbidity and mortality. Furthermore, the endogenous gasotransmitter carbon monoxide attracts attention in reducing cerebral injury. We hypothesize that extracorporeal resuscitation with additional carbon monoxide application reduces neurologic damage. DESIGN: Randomized, controlled animal study. SETTING: University research laboratory. SUBJECTS: Landrace-hybrid pigs. INTERVENTIONS: In a porcine model, carbon monoxide was added using a novel extracorporeal releasing system after resuscitation from cardiac arrest. MEASUREMENTS AND MAIN RESULTS: As markers of cerebral function, neuromonitoring modalities (somatosensory-evoked potentials, cerebral oximetry, and transcranial Doppler ultrasound) were used. Histopathologic damage and molecular markers (caspase-3 activity and heme oxygenase-1 expression) were analyzed. Cerebral oximetry showed fast rise in regional oxygen saturation after carbon monoxide treatment at 0.5 hours compared with extracorporeal resuscitation alone (regional cerebral oxygen saturation, 73% ± 3% vs 52% ± 8%; p < 0.05). Median nerve somatosensory-evoked potentials showed improved activity upon carbon monoxide treatment, whereas post-cardiac arrest cerebral perfusion differences were diminished. Histopathologic damage scores were reduced compared with customary resuscitation strategies (hippocampus: sham, 0.4 ± 0.2; cardiopulmonary resuscitation, 1.7 ± 0.4; extracorporeal cardiopulmonary resuscitation, 2.3 ± 0.2; extracorporeal cardiopulmonary resuscitation with carbon monoxide application [CO-E-CPR], 0.9 ± 0.3; p < 0.05). Furthermore, ionized calcium-binding adaptor molecule 1 staining revealed reduced damage patterns upon carbon monoxide treatment. Caspase-3 activity (cardiopulmonary resuscitation, 426 ± 169 pg/mL; extracorporeal cardiopulmonary resuscitation, 240 ± 61 pg/mL; CO-E-CPR, 89 ± 26 pg/mL; p < 0.05) and heme oxygenase-1 (sham, 1 ± 0.1; cardiopulmonary resuscitation, 2.5 ± 0.4; extracorporeal cardiopulmonary resuscitation, 2.4 ± 0.2; CO-E-CPR, 1.4 ± 0.2; p < 0.05) expression were reduced after carbon monoxide exposure. CONCLUSIONS: Carbon monoxide application during extracorporeal resuscitation reduces injury patterns in neuromonitoring and decreases histopathologic cerebral damage by reducing apoptosis. This may lay the basis for further clinical translation of this highly salutary substance.

Extracorporeal resuscitation with carbon monoxide improves renal function by targeting inflammatory pathways in cardiac arrest in pigs.

Deleterious consequences like acute kidney injury frequently occur upon successful resuscitation from cardiac arrest. Extracorporeal life support is increasingly used to overcome high cardiac arrest mortality. Carbon monoxide (CO) is an endogenous gasotransmitter, capable of reducing renal injury. In our study, we hypothesized that addition of CO to extracorporeal resuscitation hampers severity of renal injury in a porcine model of cardiac arrest. Hypoxic cardiac arrest was induced in pigs. Animals were resuscitated using a conventional [cardiopulmonary resuscitation (CPR)], an extracorporeal (E-CPR), or a CO-assisted extracorporeal (CO-E-CPR) protocol. CO was applied using a membrane-controlled releasing system. Markers of renal injury were measured, and histopathological analyses were carried out. We investigated renal pathways involving inflammation as well as apoptotic cell death. No differences in serum neutrophil gelatinase-associated lipocalin (NGAL) were detected after CO treatment compared with Sham animals (Sham 71 ± 7 and CO-E-CPR 95 ± 6 ng/mL), while NGAL was increased in CPR and E-CPR groups (CPR 135 ± 11 and E-CPR 124 ± 5 ng/mL; P < 0.05). Evidence for histopathological damage was abrogated after CO application. CO increased renal heat shock protein 70 expression and reduced inducible cyclooxygenase 2 (CPR: 60 ± 8; E-CPR 56 ± 8; CO-E-CPR 31 ± 3 µg/mL; P < 0.05). Caspase 3 activity was decreased (CPR 1,469 ± 276; E-CPR 1,670 ± 225; CO-E-CPR 755 ± 83 pg/mL; P < 0.05). Furthermore, we found a reduction in renal inflammatory signaling upon CO treatment. Our data demonstrate improved renal function by extracorporeal CO treatment in a porcine model of cardiac arrest. CO reduced proinflammatory and proapoptotic signaling, characterizing beneficial aspects of a novel treatment option to overcome high mortality.

Phosphodiesterase-4 inhibition reduces ECLS-induced vascular permeability and improves microcirculation in a rodent model of extracorporeal resuscitation.

Extracorporeal circulation can be accompanied by increased vascular permeability leading to pathological fluid balance and organ dysfunction. The second messenger cAMP is involved in capillary permeability and maintains endothelial integrity. The aim of the present study was to evaluate the effect of phosphodiesterase-4 (PDE4) inhibition with rolipram on extracorporeal circulation-induced capillary leakage, microcirculatory dysfunction, and organ injury in rodents. Rats were randomly allocated to the following groups: sham ( n = 5), venoarterial extracorporeal circulation [extracorporeal life support (ECLS), n = 7], ECLS + rolipram ( n = 7), extracorporeal resuscitation (ECPR; n = 7), and ECPR + rolipram ( n = 7). In the groups that underwent ECPR, ECLS-based cardiopulmonary resuscitation (ECPR) was performed after the induction of hypoxic cardiac arrest. Upon return of spontaneous circulation, rolipram was administered intravenously. The mesenteric microcirculation was studied using intravital microscopy, and organ specimens were harvested upon completion of the study. ECLS and ECPR induced a proinflammatory response (cytokines IL-1ß, IL-6, and TNF-α). Although PDE4 expression was upregulated in vascular tissue, PDE4 inhibition abrogated impaired microcirculation and capillary leak (albumin extravasation of the sham group: 1 ± 0.03-fold, ECLS group: 1.2 ± 0.05-fold, ECLS + rolipram group: 0.99 ± 0.04-fold, ECPR group: 1.6 ± 0.04-fold, and ECPR + rolipram group: 1.06 ± 0.02-fold from the sham group, P < 0.05). PDE4 inhibition led to stabilization of vascular cAMP levels but did not affect cytokine levels. Capillary leak was reduced, as demonstrated by the decrease of the systemic biomarkers soluble vascular-endothelial cadherin and activated complement 3. Histological analysis revealed reduced injury to the lungs and kidneys after PDE4 inhibition, with a significant decrease in systemic renal damage markers. Our findings demonstrate that extracorporeal circulation causes an inflammatory reaction associated with decreased vascular cAMP levels, increased vascular permeability, and impaired microcirculation. PDE4 inhibition proved to be capable of reducing these side effects in ECLS and ECPR, leading to reduced microcirculatory, renal, and pulmonary injury. NEW & NOTEWORTHY Various complications are common after extracorporeal circulation. Among these, endothelial injury may cause impaired microcirculation and capillary leak. Here, we report that phosphodiesterase-4 inhibition targeting endothelial cAMP is capable of reducing microvascular complications in a rodent model of extracorporeal resuscitation. Microcirculation and vascular permeability are influenced without targeting extracorporeal circulation-induced inflammation. Thus, pulmonary and renal organ protection may be conferred.

Standardized model of porcine resuscitation using a custom-made resuscitation board results in optimal hemodynamic management.

AIM: Standardized modeling of cardiac arrest and cardiopulmonary resuscitation (CPR) is crucial to evaluate new treatment options. Experimental porcine models are ideal, closely mimicking human-like physiology. However, anteroposterior chest diameter differs significantly, being larger in pigs and thus poses a challenge to achieve adequate perfusion pressures and consequently hemodynamics during CPR, which are commonly achieved during human resuscitation. The aim was to prove that standardized resuscitation is feasible and renders adequate hemodynamics and perfusion in pigs, using a specifically designed resuscitation board for a pneumatic chest compression device. METHODS AND RESULTS: A "porcine-fit" resuscitation board was designed for our experiments to optimally use a pneumatic compression device (LUCAS® II, Physio-Control Inc.), which is widely employed in emergency medicine and ideal in an experimental setting due to its high standardization. Asphyxial cardiac arrest was induced in 10 German hybrid landrace pigs and cardiopulmonary resuscitation was performed according to ERC/AHA 2015 guidelines with mechanical chest compressions. Hemodynamics were measured in the carotid and pulmonary artery. Furthermore, arterial blood gas was drawn to assess oxygenation and tissue perfusion. The custom-designed resuscitation board in combination with the LUCAS® device demonstrated highly sufficient performance regarding hemodynamics during CPR (mean arterial blood pressure, MAP 46 ±â€¯1 mmHg and mean pulmonary artery pressure, mPAP of 36 ±â€¯1 mmHg over the course of CPR). MAP returned to baseline values at 2 h after ROSC (80 ±â€¯4 mmHg), requiring moderate doses of vasopressors. Furthermore, stroke volume and contractility were analyzed using pulse contour analysis (106 ±â€¯3 ml and 1097 ±â€¯22 mmHg/s during CPR). Blood gas analysis revealed CPR-typical changes, normalizing in the due course. Thermodilution parameters did not show persistent intravascular volume shift. CONCLUSION: Standardized cardiopulmonary resuscitation is feasible in a porcine model, achieving adequate hemodynamics and consecutive tissue perfusion of consistent quality.

Molecular size and origin do not influence the harmful side effects of hydroxyethyl starch on human proximal tubule cells (HK-2) in vitro.

BACKGROUND: Recently, clinical trials revealed renal impairment induced by hydroxyethyl starch (HES) in septic patients. In prior studies, we managed to demonstrate that HES accumulated in renal proximal tubule cells (PTCs). The related pathomechanism has not yet been discovered. To validate our hypothesis that the HES molecule itself is harmful, regardless of its molecule size or origin, we conducted a comprehensive study to elucidate the influences of different HES preparations on PTC viability in vitro. METHODS: Cell viability of human PTC was measured with a cytotoxicity assay, quantifying the reduction of tetrazolium salt to colored formazan. Experiments were performed by assessing the influence of different carrier solutions of HES (balanced, nonbalanced, culture medium), different average molecular weights (70, 130, 200 kDa), different origins (potato or corn derived), and various durations of incubation (2-21 hours). Furthermore, HES 130/0.4 was fractionated by ultrafiltration, and the impact on cell viability of average single-size fractions with <3, 3 to 10, 10 to 30, 30 to 50, 50 to 100, and >100 kDa was investigated. We also tested the possible synergistic effects of inflammation induced by tumor necrosis factor-α. RESULTS: All tested HES solutions, regardless of origin or carrier matrix, decreased cell viability in an equivalent, dose-dependent manner. Coincubation with tumor necrosis factor-α did not reduce HES-induced reduction of cell viability. Minor differences were detected comparing 70, 130, and 200 kDa preparations. Analysis of fractionated HES revealed that each fraction decreased cell viability. Even small HES molecules (10-30 kDa) were significantly deleterious. CONCLUSIONS: For the first time, we were able to show that only the total mass of HES molecules applied is responsible for the harmful impact on renal PTC in vitro. Neither molecular size nor their origin showed any relevance.

Phosphodiesterase-4 inhibition as a therapeutic approach to treat capillary leakage in systemic inflammation.

In sepsis and systemic inflammation, increased microvascular permeability and consecutive breakdown of microcirculatory flow significantly contribute to organ failure and death. Evidence points to a critical role of cAMP levels in endothelial cells to maintain capillary endothelial barrier properties in acute inflammation. However, approaches to verify this observation in systemic models are rare. Therefore we tested here whether systemic application of the phosphodiesterase-4-inhibitors (PD-4-Is) rolipram or roflumilast to increase endothelial cAMP was effective to attenuate capillary leakage and breakdown of microcirculatory flow in severe lipopolysaccharide (LPS)-induced systemic inflammation in rats. Measurements of cAMP in mesenteric microvessels demonstrated significant LPS-induced loss of cAMP levels which was blocked by application of rolipram. Increased endothelial cAMP by application of either PD-4-I rolipram or roflumilast led to stabilization of endothelial barrier properties as revealed by measurements of extravasated FITC-albumin in postcapillary mesenteric venules. Accordingly, microcirculatory flow in mesenteric venules was significantly increased following PD-4-I treatment and blood gas analyses indicated improved metabolism. Furthermore application of PD-4-I after manifestation of LPS-induced systemic inflammation and capillary leakage therapeutically stabilized endothelial barrier properties as revealed by significantly reduced volume resuscitation for haemodynamic stabilization. Accordingly microcirculation was significantly improved following treatment with PD-4-Is. Our results demonstrate that inflammation-derived loss of endothelial cAMP contributes to capillary leakage which was blocked by systemic PD-4-I treatment. Therefore these data suggest a highly clinically relevant and applicable approach to stabilize capillary leakage in sepsis and systemic inflammation.

Effects of crystalloids and colloids on liver and intestine microcirculation and function in cecal ligation and puncture induced septic rodents.

BACKGROUND: Septic acute liver and intestinal failure is associated with a high mortality. We therefore investigated the influence of volume resuscitation with different crystalloid or colloid solutions on liver and intestine injury and microcirculation in septic rodents. METHODS: Sepsis was induced by cecal ligation and puncture (CLP) in 77 male rats. Animals were treated with different crystalloids (NaCl 0.9% (NaCl), Ringer's acetate (RA)) or colloids (Gelafundin 4% (Gel), 6% HES 130/0.4 (HES)). After 24 h animals were re-anesthetized and intestinal (n = 6/group) and liver microcirculation (n = 6/group) were obtained using intravital microscopy, as well as macrohemodynamic parameters were measured. Blood assays and organs were harvested to determine organ function and injury. RESULTS: HES improved liver microcirculation, cardiac index and DO(2)-I, but significantly increased IL-1ß, IL-6 and TNF-α levels and resulted in a mortality rate of 33%. Gel infused animals revealed significant reduction of liver and intestine microcirculation with severe side effects on coagulation (significantly increased PTT and INR, decreased haemoglobin and platelet count). Furthermore Gel showed severe hypoglycemia, acidosis and significantly increased ALT and IL-6 with a lethality of 29%. RA exhibited no derangements in liver microcirculation when compared to sham and HES. RA showed no intestinal microcirculation disturbance compared to sham, but significantly improved the number of intestinal capillaries with flow compared to HES. All RA treated animals survided and showed no severe side effects on coagulation, liver, macrohemodynamic or metabolic state. CONCLUSIONS: Gelatine 4% revealed devastated hepatic and intestinal microcirculation and severe side effects in CLP induced septic rats, whereas the balanced crystalloid solution showed stabilization of macro- and microhemodynamics with improved survival. HES improved liver microcirculation, but exhibited significantly increased pro-inflammatory cytokine levels. Crystalloid infusion revealed best results in mortality and microcirculation, when compared with colloid infusion.

The effects of colloid solutions on renal proximal tubular cells in vitro.

Renal failure is a common complication of critically ill patients. Colloids such as hydroxyethyl starch (HES), gelatin, or albumin are regularly used for intravascular volume resuscitation, but there are increasing reports about the nephrotoxic side effects of synthetic colloids in septic patients. Therefore, we investigated the influence of colloids (HES130/0.4 (Voluven®), gelatin (Gelafundin®), human albumin, and the crystalloid Sterofundin® ISO on cell viability of human proximal tubular (HK-2) cells. HK-2 cells were incubated with colloids (0.1%-4%) and with equivalent volumes of the crystalloid solution Sterofundin ISO. After 21 hours, cell viability of HK-2 cells was measured by EZ4U assay (dye XTT). Application of HES130/0.4 decreased cell viability significantly in a concentration-dependent manner (86.80% ± 10.79% by 0.5% HES down to 24.02% ± 4.27% by 4% HES). Human albumin (>1.25%) as well as gelatin (>1%) also showed deleterious effects on HK-2 cells. Interestingly, in lower concentrations, human albumin and the crystalloid solution Sterofundin ISO were cytoprotective in comparison with the NaCl control. In conclusion, synthetic and natural colloids showed a harmful impact on HK-2 cells in higher concentrations without any prior proinflammatory stimulus. HES130/0.4 exhibited the most distinctive harmful impact, whereas the application of crystalloid Sterofundin ISO revealed cytoprotective effects.

Phenylephrine versus cafedrine/theodrenaline (Akrinor) for the treatment of spinal anaesthesia-induced maternal hypotension during caesarean section: a retrospective single-centre cohort study.

OBJECTIVE: The main objective of this study was to assess the impact of phenylephrine and cafedrine/theodrenaline on the mother and newborn after spinal anaesthesia for caesarean section. SETTING: University teaching hospital. DESIGN: A single-centre retrospective data cohort study. PATIENTS: All obstetric patients who were scheduled for caesarean section in a 2-year period. INTERVENTIONS: Administration of either intravenous phenylephrine prophylactically or cafedrine/theodrenaline (Akrinor) reactively to maintain blood pressure after spinal anaesthesia. MAIN OUTCOME MEASURE: Maternal hypotension, heart rate during caesarean section and after admission to IMC, fetal arterial cord pH and base excess levels, maternal volume resuscitation and the use of rescue medication. RESULTS: 852 data sets could be included: n=440 Akrinor, n=412 in the phenylephrine cohort. During caesarean section blood pressure was slightly higher in the phenylephrine group compared with the Akrinor group, while hypotension <100 mm Hg systolic blood pressure (SBP) occurred significantly more often during arrival at the IMC after surgery when phenylephrine was used. Heart rate was lower and rescue medication was significantly more frequently given in the phenylephrine cohort. Irrespective of the medication used, women with baseline levels of <120 mm Hg SBP had a high risk to develop hypotension <100 mm Hg after spinal anaesthesia for caesarean section. While there was no statistical difference in mean umbilical arterial pH levels, the incidence of acidosis, defined as pH <7.2, was significantly higher with phenylephrine. CONCLUSION: Phenylephrine was not superior to Akrinor to treat spinal anaesthesia-induced maternal hypotension during caesarean section. TRIAL REGISTRATION NUMBER: DRKS00025795.

Standardized Colon Ascendens Stent Peritonitis in Rats - a Simple, Feasible Animal Model to Induce Septic Acute Kidney Injury.

AKI in septic patients is associated with increased mortality and poor outcome despite major efforts to refine the understanding of its pathophysiology. Here, an in vivo model is presented that combines a standardized septic focus to induce AKI and an intensive care (ICU) setup to provide an advanced hemodynamic monitoring and therapy comparable in human sepsis. Sepsis is induced by standardized colon ascendens stent peritonitis (sCASP). AKI is investigated functionally by measurement of blood and urine samples as well as histologically by evaluation of histopathological scores. Furthermore, the advanced hemodynamic monitoring and the possibility of repetitive blood gas sampling enable a differentiated analysis of severity of induced sepsis. The sCASP method is a standardized, reliable and reproducible method to induce septic AKI. The intensive care setup, continuous hemodynamic and gas exchange monitoring, low mortality rate as well as the opportunity of detailed analyses of kidney function and impairments are advantages of this setup. Therefore, the described method may serve as a new standard for experimental investigations of septic AKI.

Comparison of hydroxyethylstarch (HES 130/0.4) and 5% human albumin for volume substitution in pediatric neurosurgery: A retrospective, single center study.

OBJECTIVE: Colloid solutions are commonly used to maintain perioperative fluid homeostasis. In regard to perioperative infant-centered care, data about the impact of colloids are rare. New data suggest a possible positive effect of hydroxyethyl starch (HES) concerning blood brain barrier. Therefore we conduct a retrospective single center study of children scheduled for neurosurgery, age < five with a blood loss > 10% of body blood volume, receiving either 6% HES 130/0.4 or 5% human albumin (HA). RESULTS: Out of 913 patients, 86 were included (HES = 30; HA = 56). Compared to HES [16.4 ± 9.2 ml/kg body weight (mean ± SD)] HA group received more colloid volume (25.7 ± 11.3), which had more blood loss [HA 54.8 ± 45.0; HES 30.5 ± 30.0 (%) estimated blood volume] and higher fluid balances. Fibrinogen was decreased and activated partial thromboplastin time was elevated in HA group. Urinary output, creatinine and urea levels did not differ between the two groups. Serum calcium, total protein levels were lower in HES group. HA treated infants tended to have shorter ICU and hospital stays. We conclude that none of the investigated colloid solutions were without leverage to infants. Consequently randomized controlled trials about perioperative goal-directed fluid replacement of children undergoing (neuro)-surgery with major blood loss are needed.

Hydroxyethylstarch revisited for acute brain injury treatment.

Infusion of the colloid hydroxyethylstarch has been used for volume substitution to maintain hemodynamics and microcirculation after e.g., severe blood loss. In the last decade it was revealed that hydroxyethylstarch can aggravate acute kidney injury, especially in septic patients. Because of the serious risk for critically ill patients, the administration of hydroxyethylstarch was restricted for clinical use. Animal studies and recently published in vitro experiments showed that hydroxyethylstarch might exert protective effects on the blood-brain barrier. Since the prevention of blood-brain barrier disruption was shown to go along with the reduction of brain damage after several kinds of insults, we revisit the topic hydroxyethylstarch and discuss a possible niche for the application of hydroxyethylstarch in acute brain injury treatment.

Carbon monoxide has antioxidative properties in the liver involving p38 MAP kinase pathway in a murine model of systemic inflammation.

OBJECTIVE: Reactive oxygen species (ROS) are important in the hepatocellular injury process during a systemic inflammation. We examined the role of carbon monoxide (CO) on the hepatic generation of ROS with in-vivo and in-vitro models of systemic inflammation. METHODS: Using a murine model of bilateral hindlimb ischemia-reperfusion (I/R) we examined the effect of CO treatment on hepatic ROS formation, oxidative status, and cell injury. Cultured HUVEC were used to investigate intracellular pathways. RESULTS: CO treatment reduced hepatic lipid peroxidation, re-established total hepatic glutathione and glutathione disulfide (GSH/GSSG) levels and reduced hepatocellular injury. Inhibition of heme oxygenase (HO) during treatment with CO during hindlimb I/R failed to alter the antioxidant qualities provided by CO. The production of ROS after tumor necrosis factor-α (TNF-α) stimulation in HUVEC was diminished after exposure to CO. Treatment with CO during HO inhibition reduced both ROS formation and cell injury. Inhibiting the p38 MAPK (mitogen-activated protein kinase) pathway with pyridinyl imidazol (SB203580) revealed that the antioxidant potential of CO involved the activation of p38 MAPK. CONCLUSIONS: CO has direct antioxidant potential independently of any HO activity during systemic inflammation. The antioxidant effects afforded by CO involve the activation of the p38 MAPK pathway.

Hydroxyethylstarch (130/0.4) tightens the blood-brain barrier in vitro.

In order to prevent cerebral vasospasm after a subarachnoid hemorrhage (SAH), the so-called triple H-therapy (hypertension, hypervolemia, hemodilution) could be applied. In these cases, colloidal solutions containing Hydroxyethylstarch (HES) are used to induce hypervolemia. The administration of HES is very much under debate for the mentioned use, because in general the application of HES for the treatment of critical ill patients has been reduced tremendously in the last years due to its nephrotoxic effects. In this context, there are limited data investigating the influence of HES on the blood-brain barrier. These data might help to assess if a transient administration of HES is possibly justifiable to prevent cerebral ischemia during vasospasm despite the risk of an acute kidney injury. To address this question, a mouse blood-brain barrier in vitro model based on cell line cerebEND was exposed to different HES concentrations and compared to NaCl-containing control solutions. In order to assess the effects of HES on blood-brain barrier properties, cell viability, transendothelial electrical resistance, permeability of carboxyfluorescein, mRNA and protein expression and localization of tight junction proteins were determined. In summary, 1.5-4% HES attenuated cell viability in a mild, concentration dependent manner compared to the NaCl control solution (0% HES). At the mRNA level 1% and 4% HES significantly increased the expression of tight junction associated proteins (ZO-1 and occludin) and the glucose transporter Glut-1 (Slc2a1). In correspondence to this, 4% HES inhibited breakdown of the paracellular barrier in comparison to the control NaCl group (0% HES) shown by transendothelial electrical resistance values and the permeability of the paracellular marker carboxyfluorescein. These effects at the functional level were confirmed by immunofluorescence microscopic images of junctional proteins. The obtained in vitro data showed a potential for HES to counteract blood-brain barrier damage. Future studies are needed to reveal the applicability of HES as a blood-brain barrier stabilizing agent.

Carbon monoxide improves haemodynamics during extracorporeal resuscitation in pigs.

AIMS: Heart disease of different aetiology remains the leading cause of cardiac arrest (CA). Despite efforts to improve the quality of cardiopulmonary resuscitation (CPR), subsequent myocardial and systemic damage after CA still present a major long-term burden. Low-dose carbon monoxide (CO) is known to exert protective effects in cardiovascular pathophysiology but clinical applications are challenged by unfavourable delivery modes. We tested the hypothesis that extracorporeal resuscitation (E-CPR) in combination with controlled fast onset CO delivery results in improved cardiac physiology and haemodynamics. Damage-associated molecular pattern (DAMP) signalling may be part of the molecular mechanism. METHODS AND RESULTS: In an established porcine model, E-CPR was performed. While E-CPR leads to similar results as compared to a conventional CPR strategy, CO delivery in combination with E-CPR demonstrated significant cardioprotection. Cardiac performance analysis using echocardiography and thermodilution techniques showed a CO-dependent improved cardiac function compared to severe myocardial dysfunction in CPR and E-CPR (left ventricular ejection fraction: Sham 49 ± 5; CPR 26 ± 2; E-CPR 25 ± 2; CO-E-CPR 31 ± 4; P < 0.05). While sublingual microcirculation was significantly compromised in CPR and E-CPR, CO delivery demonstrated a significant improvement in microvascular function (microvascular flow index: Sham 2.9 ± 0.1; CPR 2.2 ± 0.1; E-CPR 1.8 ± 0.1; CO-E-CPR 2.7 ± 0.1; P < 0.01). Histological and serological myocardial damage markers were significantly reduced (hsTroponin-T Sham 0.01 ± 0.001; CPR 1.9 ± 0.2; E-CPR 3.5 ± 1.2; CO-E-CPR 0.5 ± 0.2 ng/mL; P < 0.05). DAMP signalling was decreased ipse facto leading to influence of cardioprotective heat shock and cyclooxygenase response. CONCLUSIONS: CO treatment restores myocardial function and improves systemic macro- and microhaemodynamics in E-CPR through a reduction in DAMPs.

Microdialysis and ultrasound elastography for monitoring of localized muscular reaction after pharmacological stimulation in rats.

OBJECTIVE: Halothane and caffeine are known to cause skeletal muscular contractions in vitro and have been proven to induce circumscribed metabolic reactions when injected into rat skeletal muscle. In this study 26 rats were investigated by either continuous application of calcium 160 mM or bolus injection of caffeine 160 mM or halothane 10% vol via a microdialysis probe in the tibialis anterior muscle. Tissue elasticity at the injection site was monitored by ultrasound strain elastography. Aim of this study was to detect (I) changes in local lactate concentrations and (II) whether these can be attributed to a muscular contraction detected by ultrasound elastography. RESULTS: Localized metabolic reactions were verified by increasing intramuscular lactate concentrations following continuous application of calcium (0.6 [0.3;0.6] to 3.6 [3.0;4.3] mmol/l after 60 min) and bolus application of caffeine (0.2 [0.2;0.3] to 1.6 [0.9;1.9] mmol/l after 30 min) and halothane (0.3 [0.1;0.3] to 4.7 [4.3;6.3] mmol/l after 30 min). However, ultrasound elastography did not detect any differences in tissue elasticity compared to control animals. The authors identified potential limitations of the study conditions, which might be crucial to avoid for future investigations.

Sphingosine-1-Phosphate Receptor-1 Agonist Sew2871 Causes Severe Cardiac Side Effects and Does Not Improve Microvascular Barrier Breakdown in Sepsis.

BACKGROUND: Endothelial barrier dysfunction is a hallmark in the pathogenesis of sepsis. Sphingosine-1-phosphate (S1P) has been proposed to be critically involved in the maintenance of endothelial barrier function predominately by activating S1P receptor-1 (S1P1). Previous studies have shown that the specific S1P1 agonist SEW2871 improves endothelial barrier function under inflammatory conditions. However, the effectiveness of SEW2871 and potential side effects remained largely unexplored in a clinically relevant model of sepsis. Therefore, this study aimed to evaluate the effects of SEW2871 in the Colon ascendens stent peritonitis (CASP) model. METHODS: Polymicrobial sepsis was induced in Sprague-Dawley rats using CASP model that enabled the monitoring of macro-hemodynamic parameters. Twelve hours after surgery, animals received either SEW2871 or sodium chloride. Mesenteric endothelial barrier function was evaluated 24 h after sepsis induction by intravital microscopy. Organ pathology was assessed in lungs. S1P levels, blood gas analyses, and blood values were measured at different time points. In parallel the effect of SEW2871 was evaluated in human dermal microvascular endothelial cells. RESULT: In vitro SEW2871 partially stabilized TNF-α-induced endothelial barrier breakdown. However, in vivo SEW2871 caused severe cardiac side effects in septic animals leading to an increased lethality. Sepsis-induced endothelial barrier dysfunction was not attenuated by SEW2871 as revealed by increased FITC-albumin extra-vasation, requirement of intravasal fluid replacement, and pulmonary edema. Interestingly, Sham-operated animals did not present any side effects after SEW2871 treatment. CONCLUSION: Our study demonstrates that the application of SEW2871 causes severe cardiac side effects and cannot attenuate the inflammation-induced endothelial barrier breakdown in a clinically relevant sepsis model, suggesting that the time point of administration and the pro-inflammatory milieu play a pivotal role in the therapeutic benefit of SEW2871.