Micro-optical prototyping of a surface acoustic wave-based point-of-care coagulation assay and first application in anticoagulated patients.

OBJECTIVE: Clinicians demand for methods to monitor effects of direct anticoagulants in the emergency setting. We recently described a coagulation assay based on surface acoustic waves (SAW) technology, which quantifies anticoagulant effects by image processing. Here we describe the first step in miniaturizing this laboratory method and provide a portable prototype that contains the optical illumination and automatic on-board image processing. METHODS: A device about the size of a shoebox was realized that contains the SAW-chip, the signal generator, the LED illumination, as well as the necessary lenses, aperture, and CCD sensor. The microspheres in the blood were mixed by SAW, and the movement of the microspheres was quantified by on-board image processing. Upon contact with activation induced coagulation, this movement ceases, and coagulation times were measured and compared to the manual methods obtained by standard fluorescent microscopy. A major advantage of our method is the low amount of blood (~ 6 µL) necessary for testing. RESULTS: Results from the prototype correlated accurately with manual methods (Pearson correlation coefficient r = 0.9644). SAW-induced clotting time under anticoagulant treatment with dabigatran or rivaroxaban was well correlated with physicochemically determined plasma concentrations of these DOACs in anticoagulated patients. Compared to manual alignment of the chip under the fluorescence microscope, the prototype had a lower coefficient of variation. CONCLUSIONS: The last evolution step towards a point-of-care (POC)-device would be the development of a cartridge (containing calcium chloride and fluorescent label) such that a drop of blood can be introduced into the reaction vessel by a fluid actuator system.

Telaprevir drug monitoring during antiviral therapy of hepatitis C graft infection after liver transplantation.

BACKGROUND & AIMS: Recurrence of hepatitis C virus (HCV) infection after orthotopical liver transplantation (OLT) is common and associated with reduced graft and patient survival. The protease inhibitor telaprevir may enhance virological response rates in patients after OLT in combination with pegylated interferon-alfa and ribavirin. Pharmacokinetic studies have shown significant drug-drug interactions between telaprevir and immunosuppression (IS), but telaprevir pharmacokinetics in OLT patients with IS are unknown. Aim of the present study was to analyse telaprevir plasma concentrations in patients with HCV genotype 1 infection after OLT in comparison to patients without OLT and IS. METHODS: Five patients with HCV genotype 1 infection after OLT and 37 HCV genotype 1-infected patients patients without prior OLT were treated with telaprevir 2250 mg daily, ribavirin 1000/1200 mg daily and pegylated interferon-alfa-2a 180 µg once weekly (triple therapy). Telaprevir plasma concentrations were analysed by liquid chromatography-electrospray-ionization-tandem mass spectrometry. HCV RNA was assessed by automatized reverse-transcription polymerase chain-reaction. RESULTS: Median (range) telaprevir plasma concentrations of TW 4, 8 and 12 were 3970 (1980-4430) ng/ml and 2520 (1870-8730) ng/ml in patients after OLT and ciclosporin- or tacrolimus-based IS, respectively, as compared to 2790 (1870-3140) in non-OLT patients (P = 0.3). In one patient with tacrolimus-based IS, telaprevir dose had to be adjusted to achieve virological response. Telaprevir plasma concentrations were steady at treatment weeks 4, 8 and 12 in patients with and without IS. CONCLUSIONS: Telaprevir drug monitoring may be necessary in patients with tacrolimus-based IS in patients with HCV graft infection after OLT.

Phenotyping the function of TRPV1-expressing sensory neurons by targeted axonal silencing.

Specific somatosensations may be processed by different subsets of primary afferents. C-fibers expressing heat-sensitive TRPV1 channels are proposed, for example, to be heat but not mechanical pain detectors. To phenotype in rats the sensory function of TRPV1(+) afferents, we rapidly and selectively silenced only their activity, by introducing the membrane-impermeant sodium channel blocker QX-314 into these axons via the TRPV1 channel pore. Using tandem mass spectrometry we show that upon activation with capsaicin, QX-314 selectively accumulates in the cytosol only of TRPV1-expressing cells, and not in control cells. Exposure to QX-314 and capsaicin induces in small DRG neurons a robust sodium current block within 30 s. In sciatic nerves, application of extracellular QX-314 with capsaicin persistently reduces C-fiber but not A-fiber compound action potentials and this effect does not occur in TRPV1(-/-) mice. Behavioral phenotyping after selectively silencing TRPV1(+) sciatic nerve axons by perineural injections of QX-314 and capsaicin reveals deficits in heat and mechanical pressure but not pinprick or light touch perception. The response to intraplantar capsaicin is substantially reduced, as expected. During inflammation, silencing TRPV1(+) axons abolishes heat, mechanical, and cold hyperalgesia but tactile and cold allodynia remain following peripheral nerve injury. These results indicate that TRPV1-expressing sensory neurons process particular thermal and mechanical somatosensations, and that the sensory channels activated by mechanical and cold stimuli to produce pain in naive/inflamed rats differ from those in animals after peripheral nerve injury.

Role of telaprevir plasma levels for predicting response to antiviral therapy in patients with hepatitis C virus genotype 1 infection.

OBJECTIVE: Telaprevir (TVR)-based triple therapy has substantially improved cure rates of hepatitis C virus (HCV) genotype 1 infection but side effects are frequent and often severe. Therefore, response predictors are needed for early identification of patients not responding to TVR-based triple therapy. MATERIAL AND METHODS: Forty-five patients (mean age: 54 ± 13 years; male gender: 60%; treatment-experienced: 82%; cirrhosis: 58%) with HCV genotype 1 infection were treated with a TVR-based triple-therapy regimen. TVR plasma levels were analyzed by liquid chromatography electrospray-ionization-tandem mass spectrometry at weeks 2, 4, 8, and 12 of antiviral therapy. On-treatment HCV RNA response was assessed at weeks 4, 12, and 24 by real-time polymerase chain reaction. RESULTS: An extended rapid virological response (eRVR) and sustained virological response (SVR) was achieved in 21 of 45 patients (47%) and 36 of 45 (80%) patients, respectively. Mean ± standard deviation TVR plasma levels at week 2 were 3.4 ± 0.2 log10 ng/ml and did not differ over time (when assessed at weeks 4, 8, and 12). TVR plasma levels at week 2 were significantly higher in patients who achieved an eRVR compared to those who did not achieve eRVR (3.5 ± 0.1 vs. 3.3 ± 0.2 log10 ng/ml; p = 0.003) but were neither associated with SVR nor with treatment-related anemia. CONCLUSION: TVR plasma levels are associated with on-treatment response but not with overall treatment efficacy. Given the high overall response rates to TVR-based triple therapy, our data suggest that TVR trough levels may not be a useful predictor of treatment response, and routine drug-level monitoring is not required.

Intranasal sufentanil/ketamine analgesia in children.

BACKGROUND: The management of procedural pain in children ranges from physical restraint to pharmacological interventions. Pediatric formulations that permit accurate dosing, are accepted by children and a have a rapid onset of analgesia are lacking. OBJECTIVES: To investigate a pediatric formulation of intranasal sufentanil 0.5 mcg·kg(-1) and ketamine 0.5 mg·kg(-1) for procedural pain and to characterize the pharmacokinetic (PK) profile. METHODS: Fifty children (≥10 kg) scheduled for a painful procedure were included in this prospective nonrandomized open-label clinical trial. Thirteen of these children had central venous access for drug assay sampling; enabling a compartmental PK analysis using nonlinear mixed-effects models. Pain intensity before and during the procedure was measured using age-appropriate pain scales. Heart rate, oxygen saturation and sedation were recorded. RESULTS: Children had a mean age of 8.8 (sd 4.9) years and weight 35.2 (sd 20.1) kg. Sufentanil/ketamine nasal spray was effective (procedural pain intensity scores ≤5 (0-10)) in 78% of the painful procedures. The spray was well accepted by 94% of the children. Oxygen saturation and heart rate remained stable, and sedation was minimal. The bioavailability of sufentanil and ketamine was 24.6% and 35.8%, respectively. Maximum plasma concentration (Cmax) of sufentanil was 0.042 mcg·l(-1) (coefficient of variation (CV) 12.9%) at 13.8 min (CV 12.4%) (Tmax). Cmax for ketamine was 0.102 mg·l(-1) (CV 10.8%), and Tmax was 8.5 min (CV 17.3%). CONCLUSION: Sufentanil/ketamine nasal spray provided rapid onset of analgesia for a variety of painful procedures with few adverse effects and has promising features for use in pediatric procedural pain management.

Inhibition of GTP cyclohydrolase attenuates tumor growth by reducing angiogenesis and M2-like polarization of tumor associated macrophages.

GTP cyclohydrolase (GCH1) is the key-enzyme to produce the essential enzyme cofactor, tetrahydrobiopterin. The byproduct, neopterin is increased in advanced human cancer and used as cancer-biomarker, suggesting that pathologically increased GCH1 activity may promote tumor growth. We found that inhibition or silencing of GCH1 reduced tumor cell proliferation and survival and the tube formation of human umbilical vein endothelial cells, which upon hypoxia increased GCH1 and endothelial NOS expression, the latter prevented by inhibition of GCH1. In nude mice xenografted with HT29-Luc colon cancer cells GCH1 inhibition reduced tumor growth and angiogenesis, determined by in vivo luciferase and near-infrared imaging of newly formed blood vessels. The treatment with the GCH1 inhibitor shifted the phenotype of tumor associated macrophages from the proangiogenic M2 towards M1, accompanied with a shift of plasma chemokine profiles towards tumor-attacking chemokines including CXCL10 and RANTES. GCH1 expression was increased in mouse AOM/DSS-induced colon tumors and in high grade human colon and skin cancer and oppositely, the growth of GCH1-deficient HT29-Luc tumor cells in mice was strongly reduced. The data suggest that GCH1 inhibition reduces tumor growth by (i) direct killing of tumor cells, (ii) by inhibiting angiogenesis, and (iii) by enhancing the antitumoral immune response.

Pharmacokinetics of intraluminally administered serum papaverine for spasm prophylaxis of the internal mammary artery.

BACKGROUND: Papaverine (Paveron N™ Linden Arzneimittel Vertrieb GmbH, Germany) is a widely used agent for preventing spasm in mammary artery preparations. The question addressed in this study is whether the intraluminal administration of papaverine can result in detectable absorption of the drug into the systemic arterial circulation. METHODS: In 15 patients (age 65 ± 6 years; body mass index 28.9 ± 3.7), an internal mammary artery (IMA) was prepared during coronary artery bypass grafting (CABG). A maximum of 3 mL of a 1 mg/1 mL diluted papaverine solution was injected intravascularly (intraluminally) for spasm prophylaxis. The IMA was closed proximally and distally with bulldog clamps. Blood samples were taken immediately after administration (T1), after 20 minutes (T2), and at the end of the operation (T3). Samples were measured in a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system consisting of a binary pump from Agilent (Waldbronn, Germany) coupled to a high-throughput screening (HTS) PAL injection system (CTC, Zwingen, Switzerland) and a tandem mass spectrometer (API 4000, AB Sciex, Darmstadt, Germany). Papaverine was analyzed in positive mode using an electrospray ion source. Quantitation was performed using Analyst 1.5 software (AB Sciex, Darmstadt, Germany). RESULTS: The newly developed LC-MS/MS method was successfully established for the detection of papaverine in plasma samples. The highest plasma papaverine levels were determined at time point T1 (mean 54.7 ± 39 ng/mL, range 16.6-179 ng/mL). The concentration was already halved 20 minutes after administration (T2) (mean 23.3 ± 2 ng/mL, range 4.6-118 ng/mL). Because of the short half-life and the hemodilution in the extracorporeal circulation, at the end of the operation papaverine (T3) had already fallen to just above the limit of detection (mean 4.1 ± 3.9 ng/mL, range 1.3-16.9 ng/mL). At time point T1, a significant negative correlation was determined between plasma levels and systemic diastolic, but not systolic, blood pressure. CONCLUSION: Papaverine was successfully determined systemically in plasma by LC-MS/MS after intraluminal administration in the IMA. Systemic circulatory effects are dependent on the detected quantity. Group size and the absence of a control group are considerable limitations.

Beta adrenoceptor blockade ameliorates impaired glucose tolerance and alterations of the cerebral ceramide metabolism in an experimental model of ischemic stroke.

BACKGROUND: Sphingolipids are versatile signaling molecules derived from membrane lipids of eukaryotic cells. Ceramides regulate cellular processes such as proliferation, differentiation and apoptosis and are involved in cellular stress responses. Experimental evidence suggests a pivotal role of sphingolipids in the pathogenesis of cardiovascular diseases, including ischemic stroke. A neuroprotective effect has been shown for beta-adrenergic antagonists in rodent stroke models and supported by observational clinical data. However, the exact underlying pathophysiological mechanisms are still under investigation. We aimed to examine the influence of propranolol on the ceramide metabolism in the stroke-affected brain. METHODS: Mice were subjected to 60 or 180 min transient middle cerebral artery occlusion (tMCAO) and infarct size, functional neurological deficits, glucose tolerance, and brain ceramide levels were assessed after 12, 24, and 72 h to evaluate whether the latter two processes occur in a similar time frame. Next, we assessed the effects of propranolol (10 mg/kg bw) at 0, 4 and 8 h after tMCAO and FTY720 (fingolimod; 1 mg/kg) on infarct size, functional outcome, immune cell counts and brain ceramide levels at 24 h after 60 min tMCAO. RESULTS: We found a temporal coincidence between stroke-associated impaired glucose tolerance and brain ceramide accumulation. Whereas propranolol reduced ischemic lesion size, improved functional outcome and reduced brain ceramide accumulation without an effect on circulating immune cells, FTY720 showed the known neuroprotective effect and strong reduction of circulating immune cells without affecting brain ceramide accumulation. CONCLUSIONS: Propranolol ameliorates both stroke-associated impairment of glucose tolerance and brain ceramide accumulation which are temporally linked, strengthening the evidence for a role of the sympathetic nervous system in regulating post-stroke glucose metabolism and its metabolic consequences in the brain.

Microfluidic coagulation assay for monitoring anticoagulant therapy in acute stroke patients.

Reliable detection of anticoagulation status in patients treated with non-vitamin K antagonist oral anticoagulants (NOACs) is challenging but of importance especially in the emergency setting. This study evaluated the potential of a whole-blood clotting time assay based on Surface Acoustic Waves (SAW-CT) in stroke-patients. The SAW-technology was used for quick and homogenous recalcification of whole blood inducing a surface-activated clotting reaction quantified and visualised by real-time fluorescence microscopy with automatic imaging processing. In 20 stroke or transient ischaemic attack (TIA)-patients taking NOACs kinetics of SAW-CT were assessed and correlated to other coagulation parameters (PT, aPTT) and NOAC-plasma concentration measured by tandem mass spectrometry (LC-MS/MS). In 225 emergency patients with suspicion of acute stroke or TIA, SAW-CT values were assessed. Mean (± SD) SAW-CT in non-anticoagulated stroke patients (n=180) was 124 s (± 21). In patients on dabigatran or rivaroxaban, SAW-CT values were significantly higher 2 and 8 hours (h) after intake rising up to 267 seconds (s) (dabigatran, 2 h after intake) and 250 s (rivaroxaban, 8 h after intake). In patients on apixaban, SAW-CT values were only moderately increased 2 h after intake (SAW-CT 153 s). In emergency patients, SAW-CT values were significantly higher in NOAC and vitamin K antagonist (VKA)-treated as compared to non-anticoagulated patients. In conclusion, the SAW-CT assay is capable to monitor anticoagulant level and effect in patients receiving dabigatran, rivaroxaban and the VKA phenprocoumon. It has a limited sensitivity for apixaban-detection. If specific SAW-CT results were used as cut-offs, SAW-CT yields high diagnostic accuracy to exclude relevant rivaroxaban and dabigatran concentrations in stroke-patients.

Eosinophils Contribute to Intestinal Inflammation via Chemoattractant Receptor-homologous Molecule Expressed on Th2 Cells, CRTH2, in Experimental Crohn's Disease.

BACKGROUND AND AIMS: Prostaglandin [PG] D2 activates two receptors, DP and CRTH2. Antagonism of CRTH2 has been shown to promote anti-allergic and anti-inflammatory effects. We investigated whether CRTH2 may play a role in Crohn's disease [CD], focusing on eosinophils which are widely present in the inflamed mucosa of CD patients and express both receptors. METHODS: Using the 2,4,6-trinitrobenzenesulfonic acid [TNBS]-induced colitis model, involvement of CRTH2 in colitis was investigated by pharmacological antagonism, immunohistochemistry, Western blotting, immunoassay, and leukocyte recruitment. Chemotactic assays were performed with isolated human eosinophils. Biopsies and serum samples of CD patients were examined for presence of CRTH2 and ligands, respectively. RESULTS: High amounts of CRTH2-positive cells, including eosinophils, are present in the colonic mucosa of mice with TNBS colitis and in human CD. The CRTH2 antagonist OC-459, but not the DP antagonist MK0524, reduced inflammation scores and decreased TNF-α, IL-1ß, and IL-6 as compared with control mice. OC-459 inhibited recruitment of eosinophils into the colon and also inhibited CRTH2-induced chemotaxis of human eosinophils in vitro. Eosinophil-depleted ΔdblGATA knockout mice were less sensitive to TNBS-induced colitis, whereas IL-5 transgenic mice with lifelong eosinophilia were more severely affected than wild types. In addition, we show that serum levels of PGD2 and Δ(12)-PGJ2 were increased in CD patients as compared with control individuals. CONCLUSIONS: CRTH2 plays a pro-inflammatory role in TNBS-induced colitis. Eosinophils contribute to the severity of the inflammation, which is improved by a selective CRTH2 antagonist. CRTH2 may, therefore, represent an important target in the pharmacotherapy of CD.

Identification and characterisation of a prototype for a new class of competitive PPARγ antagonists.

Understanding of the physiological role of peroxisome proliferator-activated receptor gamma (PPARγ) offers new opportunities for the treatment of cancers, immune disorders and inflammatory diseases. In contrast to PPARγ agonists, few PPARγ antagonists have been studied, though they do exert immunomodulatory effects. Currently, no therapeutically useful PPARγ antagonist is commercially available. The aim of this study was to identify and kinetically characterise a new competitive PPARγ antagonist for therapeutic use. A PPARγ-dependent transactivation assay was used to kinetically characterise (E)-2-(5-((4-methoxy-2-(trifluoromethyl)quinolin-6-yl)methoxy)-2-((4-(trifluoromethyl)benzyl)oxy)-benzylidene)-hexanoic acid (MTTB) in kidney, T and monocytic cell lines. Cytotoxic effects were analysed and intracellular accumulation of MTTB was assessed by tandem mass spectrometry (LC-MS/MS). Potential interactions of MTTB with the PPARγ protein were suggested by molecular docking analysis. In contrast to non-competitive, irreversible inhibition caused by 2-chloro-5-nitrobenzanilide (GW9662), MTTB exhibited competitive antagonism against rosiglitazone in HEK293T and Jurkat T cells, with IC50 values in HEK293T cells of 4.3µM and 1.6µM, using the PPARγ ligand binding domain (PPARγ-LBD) and the full PPARγ protein, respectively. In all cell lines used, however, MTTB showed much higher intracellular accumulation than GW9662. MTTB alone exhibited weak partial agonistic effects and low cytotoxicity. Molecular docking of MTTB with the PPARγ-LBD supported direct interaction with the nuclear receptor. MTTB is a promising prototype for a new class of competitive PPARγ antagonists. It has weak partial agonistic and clear competitive antagonistic characteristics associated with rapid cellular uptake. Compared to commercially available PPARγ modulators, this offers the possibility of dose regulation of PPARγ and immune responses.

Lipoxin A4: problems with its determination using reversed phase chromatography-tandem mass spectrometry and confirmation with chiral chromatography.

Lipoxins belong to the family of so-called pro-resolving endogenous lipid mediators which are derived from arachidonic acid and play a key role in the counter-regulation of inflammation. Arachidonic acid is also precursor of multiple pro-inflammatory lipid mediators, such as prostaglandins and leukotrienes, which are simultaneously present in biological compartments. The close structural relationship between several of these lipid mediators and the absence of blank matrix samples enormously complicates the unequivocal identification of these compounds. The determination of lipoxin A4 has been accomplished by chromatographic separation using a C18 reversed phase column and tandem mass spectrometry detection. Samples were liquid-liquid extracted with ethyl acetate before injection. Identification of the analyte was done based on three criteria: retention time, ratio of the m/z transitions and MS/MS spectrum. To avoid false positive results due to endogenous interferences, the extracted samples were re-injected into a chiral Lux Amylose-2 chromatographic column. The authors recommend the use of chiral chromatography in the determination of pro-resolving lipid mediators, together with transition area ratio and fragmentation spectra to improve selectivity for identification and quantitation purposes.

Serum autotaxin is a parameter for the severity of liver cirrhosis and overall survival in patients with liver cirrhosis--a prospective cohort study.

BACKGROUND: Autotaxin (ATX) and its product lysophosphatidic acid (LPA) are considered to be involved in the development of liver fibrosis and elevated levels of serum ATX have been found in patients with hepatitis C virus associated liver fibrosis. However, the clinical role of systemic ATX in the stages of liver cirrhosis was unknown. Here we investigated the relation of ATX serum levels and severity of cirrhosis as well as prognosis of cirrhotic patients. METHODS: Patients with liver cirrhosis were prospectively enrolled and followed until death, liver transplantation or last contact. Blood samples drawn at the day of inclusion in the study were assessed for ATX content by an enzyme-linked immunosorbent assay. ATX levels were correlated with the stage as well as complications of cirrhosis. The prognostic value of ATX was investigated by uni- and multivariate Cox regression analyses. LPA concentration was determined by liquid chromatography-tandem mass spectrometry. RESULTS: 270 patients were enrolled. Subjects with liver cirrhosis showed elevated serum levels of ATX as compared to healthy subjects (0.814±0.42 mg/l vs. 0.258±0.40 mg/l, P<0.001). Serum ATX levels correlated with the Child-Pugh stage and the MELD (model of end stage liver disease) score and LPA levels (r = 0.493, P = 0.027). Patients with hepatic encephalopathy (P = 0.006), esophageal varices (P = 0.002) and portal hypertensive gastropathy (P = 0.008) had higher ATX levels than patients without these complications. Low ATX levels were a parameter independently associated with longer overall survival (hazard ratio 0.575, 95% confidence interval 0.365-0.905, P = 0.017). CONCLUSION: Serum ATX is an indicator for the severity of liver disease and the prognosis of cirrhotic patients.

Cis-4-methylsphingosine is a sphingosine-1-phosphate receptor modulator.

Sphingosine-1-phosphate (S1P) acts as high affinity agonist at specific G-protein-coupled receptors, S1P(1-5), that play important roles e.g. in the cardiovascular and immune systems. A S1P receptor modulating drug, FTY720 (fingolimod), has been effective in phase III clinical trials for multiple sclerosis. FTY720 is a sphingosine analogue and prodrug of FTY720-phosphate, which activates all S1P receptors except S1P(2) and disrupts lymphocyte trafficking by internalizing the S1P(1) receptor. Cis-4-methylsphingosine (cis-4M-Sph) is another synthetic sphingosine analogue that is readily taken up by cells and phosphorylated to cis-4-methylsphingosine-1-phosphate (cis-4M-S1P). Therefore, we analysed whether cis-4M-Sph interacted with S1P receptors through its metabolite cis-4M-S1P in a manner similar to FTY720. Indeed, cis-4M-Sph caused an internalization of S1P receptors, but differed from FTY720 as it acted on S1P(2) and S1P(3) and only weakly on S1P(1), while FTY720 internalized S1P(1) and S1P(3) but not S1P(2). Consequently, pre-incubation with cis-4M-Sph specifically desensitized S1P-induced [Ca(2+)](i) increases, which are mediated by S1P(2) and S1P(3), in a time- and concentration-dependent manner. This effect was not shared by sphingosine or FTY720, indicating that metabolic stability and targeting of S1P(2) receptors were important. The desensitization of S1P-induced [Ca(2+)](i) increases was dependent on the expression of SphKs, predominantly of SphK2, and thus mediated by cis-4M-S1P. In agreement, cis-4M-S1P was detected in the supernatants of cells exposed to cis-4M-Sph. It is concluded that cis-4M-Sph, through its metabolite cis-4M-S1P, acts as a S1P receptor modulator and causes S1P receptor internalization and desensitization. The data furthermore help to define requirements for sphingosine kinase substrates as S1P receptor modulating prodrugs.