A cell-based drug delivery platform for treating central nervous system inflammation

Mesenchymal stem cells (MSCs) are promising candidates for the development of cell-based drug delivery systems for autoimmune inflammatory diseases, such as multiple sclerosis (MS). Here, we investigated the effect of Ro-31-8425, an ATP-competitive kinase inhibitor, on the therapeutic properties of MSCs. Upon a simple pretreatment procedure, MSCs spontaneously took up and then gradually released significant amounts of Ro-31-8425. Ro-31-8425 (free or released by MSCs) suppressed the proliferation of CD4⁺ T cells in vitro following polyclonal and antigen-specific stimulation. Systemic administration of Ro-31-8425-loaded MSCs ameliorated the clinical course of experimental autoimmune encephalomyelitis (EAE), a murine model of MS, displaying a stronger suppressive effect on EAE than control MSCs or free Ro-31-8425. Ro-31-8425-MSC administration resulted in sustained levels of Ro-31-8425 in the serum of EAE mice, modulating immune cell trafficking and the autoimmune response during EAE. Collectively, these results identify MSC-based drug delivery as a potential therapeutic strategy for the treatment of autoimmune diseases. KEY MESSAGES: MSCs can spontaneously take up the ATP-competitive kinase inhibitor Ro-31-8425. Ro-31-8425-loaded MSCs gradually release Ro-31-8425 and exhibit sustained suppression of T cells. Ro-31-8425-loaded MSCs have more sustained serum levels of Ro-31-8425 than free Ro-31-8425. Ro-31-8425-loaded MSCs are more effective than MSCs and free Ro-31-8425 for EAE therapy.

Oral Administration of the Food-Derived Hydrophilic Antioxidant Ergothioneine Enhances Object Recognition Memory in Mice

BACKGROUND

The enhancement of learning and memory through food-derived ingredients is of great interest to healthy individuals as well as those with diseases. Ergothioneine (ERGO) is a hydrophilic antioxidant highly contained in edible golden oyster mushrooms (Pleurotus cornucopiae var. citrinopileatus), and systemically absorbed by its specific transporter, carnitine/organic cation transporter OCTN1/SLC22A4.

OBJECTIVE

This study aims to examine the possible enhancement of object recognition memory by oral administration of ERGO in normal mice.

METHODS

Novel object recognition test, spatial recognition test, LC-MS/MS, Golgi staining, neuronal culture, western blotting, immunocytochemistry, and quantitative RT-PCR were utilized.

RESULT

After oral administration of ERGO (at a dose of 1-50 mg/kg) three times per week for two weeks in ICR mice, the novel object recognition test revealed a longer exploration time for the novel object than for the familiar object. After oral administration of ERGO, the spatial recognition test also revealed a longer exploration time for the spatially moved object than the unmoved one in mice fed ERGO-free diet. The discrimination index was significantly higher in the ERGO-treated group than the control in both behavioral tests. ERGO administration led to an increase in its concentration in the plasma and hippocampus. The systemic concentration reached was relevant to those found in humans after oral ERGO administration. Golgi staining revealed that ERGO administration increased the number of matured spines in the hippocampus. Exposure of cultured hippocampal neurons to ERGO elevated the expression of the synapse formation marker, synapsin I. This elevation of synapsin I was inhibited by the tropomyosin receptor kinase inhibitor, K252a. Treatment with ERGO also increased the expression of neurotrophin-3 and -5, and phosphorylated mammalian target of rapamycin in hippocampal neurons.

CONCLUSION

Oral intake of ERGO may enhance object recognition memory at its plasma concentration achievable in humans, and this enhancement effect could occur, at least in part, through the promotion of neuronal maturation in the hippocampus.

The Effect of GS-548351 on the Pharmacokinetics of Midazolam Following Multiple Doses of ANS-6637 in Healthy Adults

ANS-6637, a pro-drug of GS-548351, is a selective, reversible inhibitor of aldehyde dehydrogenase isoform 2 under development as an anticraving agent for the treatment of substance use disorders. In vitro testing indicates that GS-548351 is an inhibitor and inducer of cytochrome P450 family 3, subfamily A (CYP3A). In this phase 1 single-center, open-label, fixed-sequence drug-drug interaction study we assessed the impact of steady-state GS-548351 on single-dose pharmacokinetics of midazolam, an index substrate for CYP3A. Twelve healthy volunteers received 600 mg of ANS-6637 by mouth daily from study days 3 to 8 and a single 5-mg oral dose of midazolam on days 1 and 8. Pharmacokinetic samples were collected over 24 hours on days 1 and 8, then analyzed using liquid chromatography-tandem mass spectrometry. The prespecified no-effect range for the 90% confidence interval (CI) of the geometric mean ratio (GMR) of midazolam coadministered with ANS-6637 (day 8) compared with midazolam alone (day 1) was 0.7-1.43. There was an increase in midazolam AUC0-∞ (GMR [90%CI]) that was within the no-effect range (1.26 [1.12-1.425]) and an increase in midazolam Cmax that was outside the range (1.22 [1.03-1.45]). The AUC0-∞ (1.08 [0.91-1.27]) and Cmax (0.95 [0.75-1.2]) of 1-hydroxymidazolam, the primary metabolite of midazolam, were also within the no-effect range. A single grade 3 adverse event (alanine aminotransferase elevation) was identified and resolved following discontinuation of the study drug. Overall, multidose ANS-6637 was well tolerated and did not alter the PK of midazolam beyond a small increase in AUC0-∞ that is unlikely to be clinically significant.

Preclinical toxicology profile of squalene epoxidase inhibitors

Small cell lung cancer (SCLC) is a particularly aggressive subset of lung cancer, and identification of new therapeutic options is of significant interest. We recently reported that SCLC cell lines display a specific vulnerability to inhibition of squalene epoxidase (SQLE), an enzyme in the cholesterol biosynthetic pathway that catalyzes the conversion of squalene to 2,3-oxidosqualene. Since it has been reported that SQLE inhibition can result in dermatitis in dogs, we conducted a series of experiments to determine if SQLE inhibitors would be tolerated at exposures predicted to drive maximal efficacy in SCLC tumors. Detailed profiling of the SQLE inhibitor NB-598 showed that dogs did not tolerate predicted efficacious exposures, with dose-limiting toxicity due to gastrointestinal clinical observations, although skin toxicities were also observed. To extend these studies, two SQLE inhibitors, NB-598 and Cmpd-4″, and their structurally inactive analogs, NB-598.ia and Cmpd-4″.ia, were profiled in monkeys. While both active SQLE inhibitors resulted in dose-limiting gastrointestinal toxicity, the structurally similar inactive analogs did not. Collectively, our data demonstrate that significant toxicities arise at exposures well below the predicted levels needed for anti-tumor activity. The on-target nature of the toxicities identified is likely to limit the potential therapeutic utility of SQLE inhibition for the treatment of SCLC.

Pre-Clinical Pharmacokinetics, Tissue Distribution and Physicochemical Studies of CLBQ14, a Novel Methionine Aminopeptidase Inhibitor for the Treatment of Infectious Diseases

INTRODUCTION

CLBQ14, a derivative of 8-hydroxyquinoline, exerts its chemotherapeutic effect by inhibiting methionine aminopeptidase (MetAP), the enzyme responsible for the post-translational modification of several proteins and polypeptides. MetAP is a novel target for infectious diseases. CLBQ14 is selective and highly potent against replicating and latent Mycobacterium tuberculosis making it an appealing lead for further development.

METHODS

The physicochemical properties (solubility, pH stability and lipophilicity), in vitro plasma stability and metabolism, pre-clinical pharmacokinetics, plasma protein binding and tissue distribution of CLBQ14 in adult male Sprague-Dawley rats were characterized.

RESULTS

At room temperature, CLBQ14 is practically insoluble in water (<0.07 mg/mL) but freely soluble in dimethyl acetamide (>80 mg/mL); it has a log P value of 3.03 ± 0.04. CLBQ14 exhibits an inverse Z-shaped pH decomposition profile; it is stable at acidic pH but is degraded at a faster rate at basic pH. It is highly bound to plasma proteins (>91%), does not partition to red blood cells (B/P ratio: 0.83 ± 0.03), and is stable in mouse, rat, monkey and human plasma. CLBQ14 exhibited a bi-exponential pharmacokinetics after intravenous administration in rats, bioavailability of 39.4 and 90.0%, respectively from oral and subcutaneous route. We observed a good correlation between predicted and observed rat clearance, 1.90 ± 0.17 L/kg/h and 1.67 ± 0.08 L/kg/h, respectively. Human hepatic clearance predicted from microsomal stability data and from the single species scaling were 0.80 L/hr/kg and 0.69 L/h/kg, respectively. CLBQ14 is extensively distributed in rats; following a 5 mg/kg intravenous administration, lowest and highest concentrations of 15.6 ± 4.20 ng/g of heart and 405.9 ± 77.11 ng/g of kidneys, respectively, were observed. In vitro CYP reaction phenotyping demonstrates that CLBQ14 is metabolized primarily by CYP 1A2.

CONCLUSION

CLBQ14 possess appealing qualities of a drug candidate. The studies reported herein are imperative to the development of CLBQ14 as a new chemical entity for infectious diseases.

Liquid chromatography-tandem mass spectrometric method for the quantification of eliglustat in rat plasma and the application in a pre-clinical study

Eliglustat is an oral substrate reduction therapy drug and has been approved as a first-line treatment for adults with Gaucher disease type 1 (GD 1). In the present study, we aimed to develop and establish an accurate and simple ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the measurement of eliglustat concentration in rat plasma. The goal of chromatographic separation of eliglustat and the internal standard (bosutinib) was finished on an Acquity BEH C18 (2.1 mm × 50 mm, 1.7 μm) column. Acetonitrile and 0.1% formic acid in water were employed as the mobile phase in a mode of gradient elution with the 0.40 mL/min flow rate. The detection was carried out on a XEVO TQ-S triple quadrupole tandem mass spectrometer coupled with electrospray ionization (ESI) interface in the positive-ion mode. Multiple reaction monitoring (MRM) was used to monitor the precursor-to-product ion transitions of m/z 405.4 → 84.1 for eliglustat and m/z 530.2 → 141.2 for bosutinib (IS), respectively. It was found that the linearity of the method in the range of 1-500 ng/mL was good for eliglustat. The values of intra- and inter-day accuracy and precision were all within the acceptance limits, and no matrix effect was found in this method. The current developed method was further performed to support in vivo pharmacokinetic study of eliglustat after oral treatment with 10 mg/kg eliglustat to rats.

The endogenous cardiotonic steroid Marinobufagenin and decline in estimated glomerular filtration rate at follow-up in patients with arterial hypertension

BACKGROUND

Marinobufagenin (MBG) is an endogenous cardiotonic steroid (CTS) that inhibits the Na+/K+-ATPase. Human MBG is significantly increased in end-stage renal disease and immunization against MBG attenuates cardiovascular fibrosis in a rat model of uremic cardiomyopathy. Mineralocorticoid antagonists (MRA) block MBG binding sites and decrease proteinuria in chronic kidney disease (CKD) patients. We therefore aimed to investigate the association of MBG and albuminuria, as a marker of renal damage, as well as MBG and decline of glomerular filtration rate (GFR).

METHODS

The Graz endocrine causes of hypertension (GECOH) study is a single center study of adults routinely referred for screening of endocrine hypertension. Plasma MBG was measured by an enzyme-linked immunoassay, and in a post-hoc analysis, follow-up creatinine levels were obtained. Patients with proteinuria >3.5g/day at baseline were excluded from further evaluation.

RESULTS

We measured MBG concentrations in 40 hypertensive subjects and excluded one patient due to pre-existing proteinuria. Plasma MBG was significantly correlated with albuminuria (Spearman ρ = .357; p = .028) and proteinuria (ρ = .336; p = .039). In linear regression analysis, the association remained significant after adjustment for age, sex, and BMI (β = .306; p = .036), and for mean systolic blood pressure (β = .352; p = .034). In follow-up analyses (N = 30), MBG was significantly associated with decline in GFR after adjustment for time-to-follow-up (β = -.374; p = .042).

CONCLUSION

The findings suggest that MBG plasma concentrations were associated with albuminuria as well as decline in kidney function. Whether MBG predicts hard renal endpoints warrants further investigations.

Immediate and 30 days mortality in digoxin poisoning cases attended in the Hospital Emergency Services of Catalonia, Spain

OBJECTIVES

Digoxin poisoning is a frequent reason for seeking emergency care. This study aimed to assess mortality related to digoxin poisoning.

MATERIAL AND METHODS

Descriptive observational study of digoxin poisonings attended in the emergency departments of 4 hospitals in Catalonia from 2013 through 2015. We gathered data relevant to the poisonings and recorded immediate and 30-day mortality. Factors possibly related to mortality were explored.

RESULTS

A total of 171 digoxin poisonings were attended. Seven (4.1%) were acute and 164 (95.9%) were chronic. The immediate and 30-day mortality rates were 6.4% and 13.4%, respectively. Bivariate analysis did not identify factors related to immediate mortality. However, the variables more often associated with 30-day mortality in this analysis were acute poisoning (after which 13% died vs 2.7% of those with chronic poisoning, P=.05), suicide attempts (8.7% of whom died vs 0.7%, P=.048), more compromised renal function (21.7% vs 9.5%, P=.037), fewer neurologic symptoms (4.3% vs 17.8% with more symptoms, P=.005), higher mean digoxin concentrations (4.7 mg/dL in those who died vs 3.7 mg/dL, P=.027), and a lower Barthel index (mean [SD] 49.1 [33.4] in those who died vs 70.3 [28.5]; P=.006). Logistic regression analysis identified serum digoxin concentration to be independently associated with immediate mortality. A lower Barthel index was associated with 30-day mortality.

CONCLUSION

Immediate mortality is related to a high digoxin concentration in serum, and 30-day mortality to a low Barthel index.

Evaluation of Drug-Drug Interaction Potential between Baloxavir Marboxil and Oseltamivir in Healthy Subjects

BACKGROUND AND OBJECTIVE

Baloxavir marboxil is a prodrug that is metabolized to baloxavir acid, which suppresses viral replication by inhibiting cap-dependent endonuclease with a single oral administration. As the mode of action of baloxavir marboxil is different from that of neuraminidase inhibitors, such as oseltamivir, combination treatment with these drugs can be a treatment option, particularly for severe influenza infection. The aim of this study was to assess the drug-drug interaction between baloxavir marboxil and oseltamivir.

METHODS

Eighteen healthy adult subjects received three treatments in a crossover fashion: single administration of baloxavir marboxil 40 mg alone, repeated twice-daily administration of oseltamivir at 75 mg for 5 days, or single administration of baloxavir marboxil at 40 mg in combination with repeated twice-daily administration of oseltamivir at 75 mg for 5 days.

RESULTS

The ratios (90% confidence intervals) of maximum plasma concentration and area under the plasma concentration-time curve of baloxavir acid after co-administration compared to baloxavir marboxil alone were 1.03 (0.92-1.15) and 1.01 (0.96-1.06), respectively. The ratios (90% confidence intervals) of maximum plasma concentration and area under the plasma concentration-time curve of oseltamivir carboxylate, the active form of oseltamivir, after co-administration compared to oseltamivir alone were 0.96 (0.93-1.00) and 0.99 (0.96-1.01), respectively, at steady state on day 5. Treatment-emergent adverse events reported were mild and not considered to be related to the study drug.

CONCLUSION

The lack of a clinically meaningful drug-drug interaction between baloxavir marboxil and oseltamivir has been established.

A reliable and stable method for the determination of foretinib in human plasma by LC-MS/MS: Application to metabolic stability investigation and excretion rate

Foretinib (GSK1363089) is a multiple receptor tyrosine kinases inhibitor. In this study, a reliable, fast liquid chromatography-tandem mass spectrometric method was described for assaying foretinib in plasma, urine, and rat liver microsome samples. Simple extraction procedure by protein preciptation with acetonitrile was implemented for foretinib and brigatinib (internal standard) analysis. Chromatographic resolution of analytes was achieved on C₁₈ column with the help of isocratic mobile phase. The binary mobile phase consisted of 60% ammonium formate (10 mM, pH 4.2) and 40% acetonitrile at a flow rate of 0.25 mL/min. Run time was 3 min, and both foretinib and brigatinib were eluted within 0.74 and 1.95 min; they were detected in positive ion mode utilizing multiple reactions monitoring mode. Linearity of the proposed method ranged from 5 to 500 ng/mL (r²≥ 0.9993) in the human plasma. Lower limit of quantification and detection were 6.0 and 1.8 ng/mL, respectively. Intraday and interday precision and accuracy were 0.16 to 1.67 % and -2.39 to -0.52 %. In vitro half-life and intrinsic clearance were 24.93 min and 6.56 mL/min/kg, respectively. Literature review showed that no previous studies have been proposed for the analytical quantification of foretinib in human plasma or its metabolic stability. The established method was also applied to estimate the rate of foretinib excretion in rat urine. The developed method can be used for foretinib pharmacokinetic applications.

Association of endothelial dysfunction with cardiovascular risk factors and new-onset diabetes mellitus in patients with hypertension

Asymmetric dimethylarginine (ADMA), which is the main endogenous inhibitor of nitric oxide synthase, plays a critical role in the process of endothelial dysfunction. The authors evaluated the association between high plasma ADMA levels in patients with hypertension and the presence of cardiovascular risk factors and the development of type 2 diabetes mellitus (DM) and cardiovascular outcomes, including death. The authors evaluated 191 patients with hypertension who were stratified into two groups according to the median value of basal ADMA: those with high levels of plasma ADMA (>0.55 μmol/L) and low levels of plasma ADMA (≤0.55 μmol/L) who were prospectively evaluated over 5.8 years. High ADMA levels were seen in patients with higher weight, body mass index, waist circumference, triglycerides, uric acid, and high-sensitivity C-reactive protein, and lower levels of high-density lipoprotein cholesterol and in patients with type 2 DM. There was an association between high plasma ADMA levels and the occurrence of cardiovascular death. In a subgroup of patients with hypertension free from metabolic syndrome and DM at baseline, there was an association between high ADMA levels and the development of type 2 DM. This study confirms the association of high plasma ADMA levels and the presence of cardiovascular risk factors in patients with hypertension and suggests a positive predictive value of high plasma ADMA levels for cardiovascular death in patients with hypertension and also for the development of type 2 DM in a subgroup of patients with hypertension free from metabolic abnormalities.

Development and validation of an LC-MS/MS method for the determination of a novel thienoquinolin urea transporter inhibitor PU-48 in rat plasma and its application to a pharmacokinetic study

A specific, sensitive and stable high-performance liquid chromatographic-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitative determination of methyl 3-amino-6-methoxythieno [2,3-b]quinoline-2-carboxylate (PU-48), a novel diuretic thienoquinolin urea transporter inhibitor in rat plasma. In this method, the chromatographic separation of PU-48 was achieved with a reversed-phase C18 column (100 × 2.1 mm, 3 μm) at 35°C. The mobile phase consisted of acetonitrile and water with 0.05% formic acid added with a gradient elution at flow rate of 0.3 mL/min. Samples were detected with the triple-quadrupole tandem mass spectrometer with multiple reaction monitoring mode via electrospray ionization source in positive mode. The retention time were 6.2 min for PU-48 and 7.2 min for megestrol acetate (internal standard, IS). The monitored ion transitions were mass-to-charge ratio (m/z) 289.1 → 229.2 for PU-48 and m/z 385.3 → 267.1 for the internal standard. The calibration curve for PU-48 was linear over the concentration range of 0.1-1000 ng/mL (r2 > 0.99), and the lower limit of quantitation was 0.1 ng/mL. The precision, accuracy and stability of the method were validated adequately. The developed and validated method was successfully applied to the pharmacokinetic study of PU-48 in rats.

Glutathione sulfotransferase inhibition activity of a self-fermented beverage, Kanji

CONTEXT

Kanji, a liquid preparation of roots of Daucus carota L. ssp. sativus (Hoffm.) Arcang. var. vavilovii Mazk. (Apiaceae), may inhibit glutathione sulfotransferase (GST) activity due to ferulic acid content.

OBJECTIVES

GST inhibition activity and characterization of Kanji and methanol extract of D. carota roots, and oral absorption pattern of ferulic acid from Kanji in rats.

MATERIALS AND METHODS

GST inhibition activity of Kanji and methanol extract of D. carota roots in concentration range 0.001-100.00 mg/mL was determined using Sprague Dawley rat liver cytosolic fraction. Methanol extract upon column chromatography gave ferulic acid, which was used to characterize Kanji and determine its oral absorption pattern in Wistar rats.

RESULTS

The GST inhibition activity of Kanji (100.00 μg/mL), methanol extract of D. carota roots (100.00 μg/mL) and tannic acid (10.00 μg/mL, positive control) was found to be 0.162 ± 0.016, 0.106 ± 0.013 and 0.073 ± 0.004 μM/min/mg, respectively. Different Kanji samples and methanol extract contained ferulic acid (0.222-0.316 mg/g) and 0.77 mg/g, respectively. Ferulic acid did not appear in plasma after oral administration of Kanji.

DISCUSSION

Kanji having solid contents 80.0 μg/mL, equivalent to 0.0025 μg/mL ferulic acid, does not inhibit the activity of GST. The oral administration of Kanji, in human equivalent dose (528 mg/kg, 16.67 μg ferulic acid), to rats indicated poor absorption of ferulic acid.

CONCLUSION

Kanji having solid contents 14-36 mg/mL does not inhibit GST activity, hence may not interfere with drugs that are the substrates of GST, if taken concomitantly.

ADMA: its role in vascular disease

Endothelium-derived nitric oxide (NO) is the most potent endogenous vasodilator and, by virtue of its anti-inflammatory and anti-thrombotic effects, it is an endogenous anti-atherogenic agent. Accordingly, impairment of NO synthesis or bioactivity may increase the risk of vascular disease. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of the NO synthase pathway. Plasma levels of ADMA are increased in patients with vascular disease, or with risk factors for vascu lar disease. Preclinical and clinical studies indicate that ADMA may mediate the adverse effects of traditional risk factors on endothelial vasodilator function. By impairing endothelial function, ADMA may contribute to pulmonary or systemic hypertension, as well as to vascular disease. Several drugs known to treat cardiovas cular disease also reduce plasma ADMA levels, such as angiotensin receptor antag onists, converting enzyme inhibitors, and insulin sensitizing agents. Plasma ADMA may be a common mediator of endothelial dysfunction induced by vascular risk factors. Insights into the mechanisms by which plasma ADMA is regulated may lead to new therapeutic knowledge.

Selective Brain-Targeted Antagonism of p38 MAPKα Reduces Hippocampal IL-1β Levels and Improves Morris Water Maze Performance in Aged Rats

Background: P38 mitogen activated protein kinase (MAPK) α modulates microglia-mediated inflammatory responses and a number of neuronal physiological processes.

Objective: To evaluate pre-clinically the pharmacological effects in the brain of p38 MAPKα inhibition with a brain-penetrant specific chemical antagonist.

Methods: VX-745, a blood-brain barrier penetrant, highly selective p38 MAPKα inhibitor, and clinical stage investigational drug, was utilized. Initially, a pilot study in 26-month-old Tg2576 mice was conducted. Subsequently, a definitive dose-response study was conducted in aged (20–22 months) rats with identified cognitive deficits; n = 15 per group: vehicle, 0.5, 1.5, and 4.5 mg/kg VX-745 by oral gavage twice daily for 3 weeks. Assessments in aged rats included IL-1β, PSD-95, TNFα protein levels in hippocampus; and Morris water maze (MWM) test for cognitive performance.

Results: Drug effect could not be assessed in Tg2576 mice, as little inflammation was evident. In cognitively-impaired aged rats, VX-745 led to significantly improved performance in the MWM and significant reduction in hippocampal IL-1β protein levels, though the effects were dissociated as the MWM effect was evident at a lower dose level than that required to lower IL-1β. Drug concentration-effect relationships and predicted human doses were determined.

Conclusions: Selective inhibition of p38 MAPKα with VX-745 in aged rats reduces hippocampal IL-1β levels and improves performance in the MWM. As the two effects occur at different dose levels, the behavioral effect appears to be via a mechanism that is independent of reducing cytokine production. The predicted human doses should minimize risks of systemic toxicity.

Acrosin inhibitor detection along the boar epididymis

Epididymal sperm maturation represents a key step in the reproduction process. Spermatozoa are exposed to epididymal fluid components representing the natural environment essential for their post-testicular maturation. Changes in sperm membrane proteins are influenced by proteolytic, glycosylation and deglycosylation enzymes present in the epididymal fluid. Accordingly, the occurrence of inhibitors of these enzymes in the epididymis is very important for the regulation of sperm membrane protein processing. In the present study, we monitored acrosin inhibitor distribution in boar epididymal fluid and in spermatozoa from different segments of the organ. Using specific polyclonal antibody we registered increasing signal of the acrosin inhibitor (AI) from caput to cauda epididymis. Mass spectroscopy examination of the immunoprecipitated acrosin inhibitor (12 kDa) unequivocally identified sperm-associated acrosin inhibitor (SAAI) in the epididymal tissue. Lectin staining showed N-glycosylation in AI from boar epididymis. Protein detection of AI was supported by the results of semi-quantitative RT-PCR showing the presence of mRNA specifically coding for SAAI and similarly increasing throughout the epididymal duct, from its proximal to distal part. Additionally, the immunofluorescence technique showed the AI localization in the secretory tissue of caput, corpus and cauda epididymis, and in the acrosome region and midpiece of the sperm.

Phase I trial of weekly MK-0752 in children with refractory central nervous system malignancies: a pediatric brain tumor consortium study

PURPOSE

Amplification and high levels of NOTCH ligand expression have been identified in several types of pediatric brain tumors. A phase I trial of weekly MK-0752, an oral inhibitor of gamma-secretase, was conducted in children with recurrent central nervous system (CNS) malignancies to estimate the maximum tolerated dose, dose-limiting toxicities (DLT), pharmacokinetics (PK), and pharmacodynamics of weekly MK-0752.

METHODS

MK-0752 was administered once weekly at 1000 and 1400 mg/m(2) using a rolling-6 design. PK analysis was performed during the first course. NOTCH and HES expression was assessed by immunohistochemistry and Western blot.

RESULTS

Ten eligible patients were enrolled (median age 8.8 years; range 3.1-19.2) with diagnoses of brain stem glioma (n = 3), ependymoma (n = 2), anaplastic astrocytoma (n = 1), choroid plexus carcinoma (n = 2), medulloblastoma (n = 1), and primitive neuroectodermal tumor (n = 1). Nine were evaluable for toxicity. One DLT of fatigue occurred in the six evaluable patients enrolled at 1000 mg/m(2)/dose. No DLTs were experienced by three patients treated at 1400 mg/m(2)/dose. Non-dose-limiting grade 3 toxicities included lymphopenia, neutropenia, and anemia. Median number of treatment courses was 2 (range 1-10). Two patients continued on therapy for at least 6 months. The median (range) C(max) of MK-0752 was 88.2 μg/mL (40.6 to 109 μg/mL) and 60.3 μg/mL (59.2 to 91.9 μg/mL) in patients receiving 1000 and 1400 mg/m(2)/week, respectively. NOTCH expression was decreased in six of seven patients for whom tissue was available at 24 h post-MK-0752.

CONCLUSION

MK-0752 is well tolerated and exhibits target inhibition at 1000 and 1400 mg/m(2)/week in children with recurrent CNS malignancies.

Synthesis and biological evaluation of carbon-11 and fluorine-18 labeled tracers for in vivo visualization of PDE10A

INTRODUCTION

In vivo visualization of PDE10A using PET provides a tool to evaluate the role of PDE10A in various neuropsychiatric diseases and can also be useful in the clinical evaluation of PDE10A inhibitor drug candidates. We evaluated several carbon-11 and fluorine-18 labeled PDE10A inhibitors as potential PDE10A PET radioligands.

MATERIALS & METHODS

[(11)C]MP10, [(11)C]JNJ42071965 and four other tracers were developed. Their biodistribution was evaluated in rats. Rat plasma and brain radiometabolites were quantified. Baseline microPET imaging was performed in normal rats and PDE10A knockout (KO) and wild-type (WT) mice. Blocking and displacement studies were conducted. The selectivity of the tracer binding was further studied in an ex vivo autoradiography experiment in PDE10A KO and WT mice.

RESULTS

Biodistribution showed brain uptake for all tracers in the striatum and wash-out from the cerebellum. [(11)C]1 ((11)C-MP10) had the highest specific uptake index (striatum (S) vs. cerebellum (C) ratios (S/C)-1) at 60 min (7.4). [(11)C]5 ([(11)C]JNJ42071965) had a high index at the early time points (1.0 and 3.7 at 2 and 30 min p.i., respectively). The affinity of [(11)C]4, [(18)F]3 and [(18)F]6 was too low to visualize PDE10A using microPET. [(11)C] 2 showed a specific binding, while kinetics of [(11)C]1 were too slow. [(11)C]5 reached equilibrium after 10 min (uptake index=1.2). Blocking and displacement experiments in rats and baseline imaging in PDE10A KO mice showed specific and reversible binding of [(11)C]5 to PDE10A.

CONCLUSIONS

We successfully radiolabeled and evaluated six radiotracers for their potential to visualize PDE10A in vivo. While [(11)C]1 had the highest striatal specific uptake index, its slow kinetics likely compromise clinical use of this tracer. [(11)C]5 has a relatively high striatum-to-background ratio and fast kinetic profile, which makes it a valuable carbon-11 alternative.

Low-dose rapamycin (sirolimus) effects in autosomal dominant polycystic kidney disease: an open-label randomized controlled pilot study

BACKGROUND AND OBJECTIVES

The two largest studies of mammalian target of rapamycin inhibitor treatment of autosomal dominant polycystic kidney disease (ADPKD) demonstrated no clear benefit on the primary endpoint of total kidney volume (TKV) or on eGFR. The present study evaluated two levels of rapamycin on the 12-month change in (125)I-iothalamate GFR (iGFR) as the primary endpoint and TKV secondarily.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a 12-month open-label pilot study, 30 adult patients with ADPKD were randomly assigned to low-dose (LD) rapamycin (rapamycin trough blood level, 2-5 ng/ml) (LD group, n=10), standard-dose (STD) rapamycin trough level (>5-8 ng/ml) (STD group, n=10), or standard care (SC group, n=10). They were evaluated with iGFR and noncontrast computed tomography.

RESULTS

Change in iGFR at 12 months was significantly higher in the LD group (7.7±12.5 ml/min per 1.73 m(2); n=9) than in the SC group (-11.2 ± 9.1 ml/min per 1.73 m(2); n=9) (LD versus SC: P<0.01). Change in iGFR at 12 months in the STD group (1.6 ± 12.1 ml/min per 1.73 m(2); n=8) was not significantly greater than that in the SC group (P=0.07), but it was in the combined treatment groups (LD+STD versus SC: P<0.01). Neither eGFR calculated by the CKD-Epidemiology Collaboration equation nor TKV (secondary endpoint) changed significantly from baseline to 12 months in any of the groups. On the basis of results of the mixed model, during the study, patients in the LD group had significantly lower trough blood levels of rapamycin (mean range ± SD, 2.40 ± 0.64 to 2.90 ± 1.20 ng/ml) compared with those in the STD group (3.93 ± 2.27 to 5.77 ± 1.06 ng/ml) (P<0.01).

CONCLUSION

Patients with ADPKD receiving LD rapamycin demonstrated a significant increase in iGFR compared with those receiving standard care, without a significant effect on TKV after 12 months.

Determination of bioactive components in Chinese herbal formulae and pharmacokinetics of rhein in rats by UPLC-MS/MS

Rhein (4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid, cassic acid) is a pharmacological active component found in Rheum palmatum L. the major herb of San-Huang-Xie-Xin-Tang (SHXXT), a medicinal herbal product used as a remedy for constipation. Here we have determined multiple bioactive components in SHXXT and investigated the comparative pharmacokinetics of rhein in rats. A sensitive and specific method combining liquid chromatography with electrospray ionization tandem mass spectrometry has been developed and validated to simultaneously quantify six active compounds in the pharmaceutical herbal product SHXXT to further study their pharmacokinetics in rats. Multiple reaction monitoring (MRM) was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. There were no significant matrix effects in the quantitative analysis and the mean recovery for rhein in rat plasma was 91.6%±3.4%. The pharmacokinetic data of rhein demonstrate that the herbal formulae or the single herbal extract provide significantly higher absorption rate than the pure compound. This phenomenon suggests that the other herbal ingredients of SHXXT and rhubarb extract significantly enhance the absorption of rhein in rats. In conclusion, the herbal formulae (SHXXT) are more efficient than the single herb (rhubarb) or the pure compound (rhein) in rhein absorption.

Asymmetric dimethylarginine and critical illness

PURPOSE OF REVIEW

Asymmetric dimethylarginine (ADMA) is an analog of arginine and functions as an endogenous inhibitor of the nitric oxide synthase, which forms nitric oxide. Nitric oxide is crucial for perfusion of vital organs and is an important signaling agent in the development of critical illness. The role of ADMA in the pathophysiological mechanisms underlying critical illness is widely studied in the last decades, and recently it has become clear that ADMA should not be overlooked by clinicians working at the ICU. The aim of this review is to describe new insights into the role of ADMA in critical illness and its clinical relevance.

RECENT FINDINGS

High levels of ADMA are found in critically ill patients, because of higher levels of protein methylation, increased rate of protein turnover, decreased activity of dimethylamine dimethylaminohydrolase, and impaired renal and hepatic clearance capacity. These high levels are an independent risk factor for cardiac dysfunction, organ failure, and ICU mortality. The arginine : ADMA ratio in particular is of clinical importance and the restoration of this ratio is expedient to restore several functions that are disturbed during critical illness.

SUMMARY

Elevated ADMA levels occur in critically ill patients, which is detrimental for morbidity and mortality. The arginine : ADMA ratio should be restored to maintain nitric oxide production and therewith improve the clinical outcome of the patient.

Inhibition of dehydroepiandosterone sulfate action in androgen-sensitive tissues by EM-1913, an inhibitor of steroid sulfatase

Steroid sulfatase (STS) plays an important role in the formation of estrogens and androgens by allowing the conversion of inactive circulating sulfated steroids into active hormones. These steroids support the development and growth of a number of hormone-dependent cancers, including prostate cancer. Here, we tested a non-estrogenic and non-androgenic inhibitor of steroid STS, namely EM-1913, with special attention to its potential use in the treatment of prostate cancer. After determining the required dosage of dehydroepiandrosterone sulfate (DHEAS) needed to stimulate the ventral prostate and seminal vesicles in castrated rats, we measured that EM-1913 partially (26%) and almost entirely blocked (81%) the stimulating effect of DHEAS on ventral prostates and seminal vesicles, respectively. In addition, the homogenization of these two tissues allowed us to confirm that they were completely deprived of STS activity following a treatment with EM-1913. This effect is also reflected in blood, since the plasma level of DHEAS was increased in animals treated with EM-1913, whereas the levels of dehydroepiandrosterone (DHEA) and dihydrotestosterone (DHT), two DHEAS metabolites, meanwhile decreased. From these results, we concluded that STS inhibitor EM-1913 is a good candidate for additional preclinical studies.

Potential of lichen secondary metabolites against Plasmodium liver stage parasites with FAS-II as the potential target

Chemicals targeting the liver stage (LS) of the malaria parasite are useful for causal prophylaxis of malaria. In this study, four lichen metabolites, evernic acid (1), vulpic acid (2), psoromic acid (3), and (+)-usnic acid (4), were evaluated against LS parasites of Plasmodium berghei. Inhibition of P. falciparum blood stage (BS) parasites was also assessed to determine stage specificity. Compound 4 displayed the highest LS activity and stage specificity (LS IC50 value 2.3 μM, BS IC50 value 47.3 μM). The compounds 1-3 inhibited one or more enzymes (PfFabI, PfFabG, and PfFabZ) from the plasmodial fatty acid biosynthesis (FAS-II) pathway, a potential drug target for LS activity. To determine species specificity and to clarify the mechanism of reported antibacterial effects, 1-4 were also evaluated against FabI homologues and whole cells of various pathogens (S. aureus, E. coli, M. tuberculosis). Molecular modeling studies suggest that lichen acids act indirectly via binding to allosteric sites on the protein surface of the FAS-II enzymes. Potential toxicity of compounds was assessed in human hepatocyte and cancer cells (in vitro) as well as in a zebrafish model (in vivo). This study indicates the therapeutic and prophylactic potential of lichen metabolites as antibacterial and antiplasmodial agents.

Hyaluronidases and their inhibitors in the serum of colorectal carcinoma patients

Colorectal cancer is the third most commonly diagnosed type of cancer. Hyaluronan is involved in this malignancy. Moreover, hyaluronidases - its degrading enzymes - display controversial roles regarding their involvement in tumor development. HYAL-1 is the major tumor derived hyaluronidase. The aim of the study was the determination and evaluation of hyaluronidase levels in serum of colorectal cancer patients, before and after surgery, with a view to assessing its potential role as a tumor marker for recurrence. By zymography and Western blotting, it was confirmed that HYAL-1 was the only hyaluronidase present in samples. Quantification of its activity indicated a statistically significant decrease in samples seven days postoperatively, compared with the respective ones before surgery. HYAL-1 levels before surgery were significantly reduced in comparison with healthy samples and samples one year postoperatively. Hyaluronidase inhibitor activity was demonstrated under mild alkaline conditions via reverse zymography. A statistically significant increase was observed in samples seven days postoperatively, when compared with samples before surgery. HYAL-1 levels in sera of colorectal cancer patients were lower than those of healthy population, possibly because of the local accumulation of the enzyme in tumor microenvironment. A gradual elevation up to one year postoperatively to reach healthy levels might indicate a role of HYAL-1 levels in cancer.

Absolute Bioavailability of Imatinib (Glivec®) Orally versus Intravenous Infusion

The purpose of this study was to investigate the absolute bioavailability of a single oral dose of imatinib (Glivec), 400 mg (capsules vs. oral solution), compared with imatinib, 100 mg (intravenous [i.v.] infusion), in healthy subjects. Twelve subjects received a single treatment in each treatment period: a 400-mg oral dose of imatinib in capsule form or as a solution or a 100-mg i.v. infusion of imatinib. Plasma imatinib concentrations were measured following each treatment; pharmacokinetic parameters and absolute bioavailability were determined. Absolute bioavailability values (compared with i.v. infusion) for the imatinib capsule and oral solution were 98.3% and 97.2%, respectively. Both the rate and extent of imatinib absorption, as measured by C(max), partial AUC, and total AUC, were similar for the oral solution and the imatinib capsule intended for the market. The 400-mg oral dose of imatinib, as a capsule or a solution, was completely absorbed and was almost completely bioavailable (> 97%).

A method for direct assessment of tissue-nonspecific alkaline phosphatase (TNAP) inhibitors in blood samples

Tissue nonspecific alkaline phosphatase (TNAP) is one of four human alkaline phosphatases (AP), a family of exocytic enzymes that catalyze hydrolysis of phospho-monoesters in bone, liver, kidney, and various other tissues. Overexpression of TNAP gives rise to excessive bone and soft tissue mineralization, including blood vessel calcification. Our prior screening campaigns have found several leads against this attractive therapeutic target using in vitro assay with a recombinant enzyme; these compounds were further optimized using medicinal chemistry approaches. To prioritize compounds for their use in animal models, we have designed and developed a biomarker assay for in situ detection of TNAP activity within human and mouse blood samples at physiological pH. This assay is suitable for screening compounds in 1,536-well plates using blood plasma from different mammalian species. The user may choose from two different substrates based on the need for greater assay simplicity or sensitivity.

Asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, interacts with gastric oxidative metabolism and enhances stress-induced gastric lesions

Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthase known to exert vasoconstriction of vascular bed. The elevation of ADMA has been considered as the cardiovascular risk factor associated with hyperlipidemia, hypercholesterolemia and metabolic syndrome. ADMA is produced by the action of dimethylarginine dimethylaminohydrolase (DDAH), which hydrolyzes ADMA to L-citrulline and dimethylamine. Previous studies have shown that endogenous NO plays an important role in the mechanism of gastric mucosal defense, but the role of ADMA in the pathogenesis of serious clinical entity, such as the acute gastric mucosal injury induced by stress has been little studied. In present study, we determined the effect of intragastric (i.g.) pretreatment with ADMA applied in graded doses ranging from 0.1 up to 20 mg/kg on gastric mucosal lesions induced by 3.5 h of water immersion and restraint stress (WRS). The number of gastric lesions was determined by planimetry and the gastric blood flow (GBF) was assessed by laser Doppler technique. The malondialdehyde and 4-hydroxynonenal (MDA+4-HNE) concentration, as an index of oxygen radical-lipid peroxidation was assessed in the gastric mucosa in rats exposed to WRS with or without ADMA administration. Proinflammatory cytokines IL-1β, TNF-α, superoxide dismutase (SOD) and glutathione peroxidase (GPx) mRNAs in the gastric mucosa and plasma levels of ADMA, IL-1β and TNF-α were analyzed by RT-PCR and ELISA, respectively. The exposure of rats to WRS for 3.5 h produced acute gastric lesions accompanied by a significant rise in the plasma ADMA levels and a significant fall in the GBF, an increase in MDA+4-HNE concentrations and the significant increase in the expression and release of IL-1β and TNF-α. The pretreatment with ADMA, applied i.g. 30 min before WRS dose-dependently, aggravated WRS damage and this effect was accompanied by a further significant fall in the GBF. The ADMA induced exacerbation of WRS lesions and the accompanying rise in the plasma ADMA levels and the fall in GBF were significantly attenuated by concurrent treatment with glyceryl trinitrate (GTN) (10 mg/kg i.g.) in the presence of ADMA. Administration of ADMA resulted in a significant decrease in the expression of SOD and GPx mRNAs and the up-regulation of mRNA for IL-1β and TNF-α followed by an increase in these plasma cytokine levels as compared to respective values observed in vehicle-pretreated animals. We conclude that 1) ADMA could be implicated in the mechanism of WRS-induced ulcerogenesis, 2) ADMA exacerbates WRS-induced gastric lesions due to enhancement in neutrophil dependent lipid peroxidation and overexpression and release of proinflammatory cytokines IL-1β and TNF-α and a potent depletion of antioxidative enzymes SOD and GPx expression and activity.

High tea and vegetable consumption is associated with low ADMA generation in older healthy subjects

Asymmetric dimethylarginine (ADMA) has been recognized as a marker of cardiovascular risk. We sought to investigate whether consumption of tea, coffee, fruit or vegetables is associated with ADMA. In 148 consecutive apparently healthy subjects (104 men and 44 women aged 40 to 70), daily tea, coffee, fruit and vegetable consumption was ascertained by questionnaire. Plasma ADMA, symmetric dimethylarginine (SDMA), and l-arginine levels were measured by high-performance liquid chromatography. Median tea and coffee consumption was 2 cups/d, while vegetable and fruit intake was 152 (120-179)g/d and 120 (108-134)g/d, respectively. Median plasma ADMA, SDMA and arginine were 0.47 (0.43-0.53)μmol/L, 0.59 (0.54-0.66)μmol/L and 86 (68-101)μmol/L, respectively. ADMA correlated inversely with tea (r = -0.70, P < .0001) and vegetable consumption (r = -0.50, P < .0001) even after adjustment for age, sex, body mass index, smoking status, and potential dietary and biochemical parameters. No association between ADMA and fruit consumption was found. ADMA correlated positively with coffee intake (r = 0.37, P < .0001), although these associations were less potent after adjustment for dietary factors. Higher tea and vegetable intake is associated with lower plasma ADMA levels in healthy middle-aged subjects.

Esterase inhibitors as ester-containing drug stabilizers and their hydrolytic products: potential contributors to the matrix effects on bioanalysis by liquid chromatography/tandem mass spectrometry

RATIONALE

Esterase inhibitors are widely used to stabilize ester-containing drugs in biological matrices for quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) assays. These co-existing inhibitors could cause matrix effects on bioanalysis and jeopardize the assay performance. We therefore developed an LC/MS/MS methodology to monitor the fate of inhibitors and evaluate their matrix effects, which is described in this study.

METHODS

Human plasma containing 20 mM of diisopropylfluorophosphate (DFP), paraoxon, eserine, phenylmethylsulfonyl fluoride (PMSF) or 2-thenoyltrifluoroacetone (TTFA) was extracted by liquid-liquid extraction (LLE) and analyzed by an LC/MS/MS assay for BMS-068645 (a model drug) with additional pre-optimized selected reaction monitoring (SRM) transitions using positive/negative electrospray ionization (ESI) mode for each inhibitor. Hydrolytic products were characterized by product ion or neutral loss scan LC/MS/MS analysis. The matrix effect contribution from each inhibitor was evaluated by post-column infusion of BMS-068645.

RESULTS

In the extracted samples by LLE, SRM chromatograms revealed the presence of paraoxon, eserine and TTFA with peak intensity of >2.50E08. Three DFP hydrolytic products, diisopropyl phosphate (DP), triisopropyl phosphate (TP) and DP dimer, and one PMSF hydrolytic product, phenymethanesulfonic acid (PMSA), were identified in the extracted samples. In post-column infusion profiles, ion suppression or enhancement was observed in the retention time regions of eserine (~10% suppression), paraoxon (~70% enhancement) and DP dimer (~20% suppression).

CONCLUSIONS

The SRM transitions described here make it possible to directly monitor the inhibitors and their hydrolytic products. In combination with post-column infusion, this methodology provides a powerful tool to routinely monitor the matrix effects-causing inhibitors, so that their matrix effects on the bioanalysis can be evaluated and minimized.

A phase I dose escalation study of AT9283, a small molecule inhibitor of aurora kinases, in patients with advanced solid malignancies

BACKGROUND

AT9283 is an inhibitor of aurora kinases A and B with antitumor activity in preclinical models. This a First in Human phase I study assessed the safety, tolerability, pharmacokinetic and pharmacodynamic properties and preliminary efficacy of AT9283.

PATIENTS AND METHODS

Patients with advanced tumors received AT9283 as a continuous central venous infusion over 3 days in cohorts of three to six patients starting at 1.5 mg/m(2)/day (equivalent to 4.5 mg/m(2)/72 h). The oral bioavailability of AT9283 was assessed in a cohort of seven patients. Pharmacodynamic analysis of biomarkers included phosphorylation of histone H3 on serine 10, proliferating cell nuclear antigen, Ki67, M30 and M65 in skin and plasma.

RESULTS

Forty patients were included in all analyses. AT9283 was generally well tolerated with main toxic effects of reversible dose-related myelosuppression, gastrointestinal disturbance, fatigue and alopecia. The dose-limiting toxicity of AT9283 was grade 3 febrile neutropenia in two patients at 36 mg/m(2)/72 h and the maximum tolerated dose (MTD) was established at 27 mg/m(2)/72 h. Systemic exposure was dose proportional. The mean oral bioavailability of a 0.9 mg/m(2) dose was 29.4% (range 11.2%-36.7%). Pharmacodynamic analyses indicated antiproliferative and apoptotic activity of AT9283. Four patients with esophageal, non-small-cell lung cancer (n = 2) and colorectal cancer demonstrated RECIST stable disease ≥ 6 months.

CONCLUSION

AT9283 was well tolerated up to the MTD of 27 mg/m(2)/72 h. AT9283 is currently assessed in phase II trials.

Ingestion of proteoglycan fraction from shark cartilage increases serum inhibitory activity against matrix metalloproteinase-9 and suppresses development of N-nitrosobis(2-oxopropyl)amine-induced pancreatic duct carcinogenesis in hamster

A water extract of shark cartilage was fractionated into acidic and basic fractions by preparative isoelectric focusing on the basis of the amphoteric nature of samples. The acidic fraction was further fractionated into ethanol-soluble and -precipitate fractions. After the carcinogenesis treatment using N-nitrosobis(2-oxopropyl)amine, hamsters received a diet containing each fraction or purified chondroichin sulfate to give 0.4% (w/w) for 50 days. Only administration of the acidic ethanol-precipitate-fraction-containing diet significantly increased serum inhibitory activity against matrix metalloproteinase (MMP)-9 and reduced the number of adenocarcinomas in the pancreatic duct. The active fraction predominantly consisted of chondroichin sulfate-containing proteoglycan. However, the purified chondroichin sulfate had no significant activity. These results suggest that the protein moiety of the proteoglycan might be involved in the increase of serum inhibitory activity against MMP-9 and suppression of pancreatic carcinogenesis in hamster.

Blood Pb and δ-ALAD inhibition in cattle and sheep from a Pb-polluted mining area

The effects of Pb pollution on cattle and sheep raised in an ancient mining area were studied through the use of blood Pb (PbB) levels and δ-aminolevulinic acid dehydratase (δ-ALAD) activity. Lead levels in livestock blood from the mining area (n=110) were significantly elevated when compared to the controls (n=79). In 91.4% of cattle (n=58) and 13.5% of sheep (n=52) sampled in the mining area, PbB levels corresponded to subclinical exposure (6-35 μg/dl). Two young cattle (<2 years) from the mining area (n=5) had PbB levels indicative of clinical poisoning (>35 μg/dl). Elevated PbB was also accompanied by δ-ALAD activity inhibition in blood, which confirms that measurable effects of Pb poisoning were taking place. Observed PbB levels suggest that a potential risk to human consumers of beef from the Pb polluted areas may also exist, as has been shown previously for game meat from the same mining area.

A nonclinical safety and pharmacokinetic evaluation of N6022: a first-in-class S-nitrosoglutathione reductase inhibitor for the treatment of asthma

S-nitrosoglutathione reductase is the primary enzyme responsible for the metabolism of S-nitrosoglutathione (GSNO), the body's main source of bioavailable nitric oxide. Through its catabolic activity, GSNO reductase (GSNOR) plays a central role in regulating endogenous S-nitrosothiol levels and protein S-nitrosation-based signaling. By inhibiting GSNOR, we aim to increase pulmonary GSNO and induce bronchodilation while reducing inflammation in lung diseases such as asthma. To support the clinical development of N6022, a first-in-class GSNOR inhibitor, a 14-day toxicology study was conducted. Sprague-Dawley rats were given 2, 10 or 50 mg/kg/day N6022 via IV administration. N6022 was well tolerated at all doses and no biologically significant adverse findings were noted in the study up to 10 mg/kg/day. N6022-related study findings were limited to the high dose group. One male rat had mild hepatocellular necrosis with accompanying increases in ALT and AST and several male animals had histological lung assessments with a slight increase in foreign body granulomas. Systemic exposure was greater in males than females and saturation of plasma clearance was observed in both sexes in the high dose group. Liver was identified as the major organ of elimination. Mechanistic studies showed dose-dependent effects on the integrity of a rat hepatoma cell line.

Robust central reduction of amyloid-β in humans with an orally available, non-peptidic β-secretase inhibitor

According to the amyloid cascade hypothesis, cerebral deposition of amyloid-β peptide (Aβ) is critical for Alzheimer's disease (AD) pathogenesis. Aβ generation is initiated when β-secretase (BACE1) cleaves the amyloid precursor protein. For more than a decade, BACE1 has been a prime target for designing drugs to prevent or treat AD. However, development of such agents has turned out to be extremely challenging, with major hurdles in cell penetration, oral bioavailability/metabolic clearance, and brain access. Using a fragment-based chemistry strategy, we have generated LY2811376 [(S)-4-(2,4-difluoro-5-pyrimidin-5-yl-phenyl)-4-methyl-5,6-dihydro-4H-[1,3]thiazin-2-ylamine], the first orally available non-peptidic BACE1 inhibitor that produces profound Aβ-lowering effects in animals. The biomarker changes obtained in preclinical animal models translate into man at doses of LY2811376 that were safe and well tolerated in healthy volunteers. Prominent and long-lasting Aβ reductions in lumbar CSF were measured after oral dosing of 30 or 90 mg of LY2811376. This represents the first translation of BACE1-driven biomarker changes in CNS from preclinical animal models to man. Because of toxicology findings identified in longer-term preclinical studies, this compound is no longer progressing in clinical development. However, BACE1 remains a viable target because the adverse effects reported here were recapitulated in LY2811376-treated BACE1 KO mice and thus are unrelated to BACE1 inhibition. The magnitude and duration of central Aβ reduction obtainable with BACE1 inhibition positions this protease as a tractable small-molecule target through which to test the amyloid hypothesis in man.

Effects of cytochrome P450 1A substrate (difloxacin) on enzyme gene expression and pharmacokinetics in crucian carp (hybridized Prussian carp)

Cytochrome P450s (CYPs) play a prominent role in drug metabolism and biotransformation which are distributed in liver of aquatic animals. However, limited information is available about CYP genes involved in drug metabolism in fish. In the present study, we explore CYP1A characterization for DIF metabolism. Firstly, we cloned and characterized the full-length cDNA sequence of a CYP1A gene from crucian carp (hybridized Prussian carp), the predicted protein sequence for CYP1A comprise 496 amino acids. The heme-binding region of the CYP1A, encompassing the amino acid sequence GLGKRRCIG, which is identical to the same region of other homologues. Secondly, we studied the difloxacin (DIF) kinetics and the effects of DIF on their corresponding CYP1A mRNA levels in liver of crucian carp. CYP1A1 mRNA expression was analyzed by real-time PCR, and DIF concentration was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). Results showed that the concentration of DIF in liver reached its peak (67.70 mg kg(-1)) at 0.5h, while the CYP1A1 gene expression was at the lowest point. CYP1A mRNA was down-regulated by 6.5 mg ml(-1) DIF in the liver of crucian carp. Thus, our work confirmed that DIF is both the substrate and inhibitor of CYP1A. The information provided a model for the potential utility of gene expression analysis and drug metabolization in fish.

Increase of CSF tyrosine and impaired serotonin turnover in tyrosinemia type I

OBJECTIVE

Psychomotor impairment has been described in hypertyrosinemia types II and III (HT III). Only recently cognitive deficits have also been reported in hypertyrosinemia type I (HT I). The pathogenic mechanisms responsible are unknown. Since implementation of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC, Nitisinone (Swedish Orphan International)) in the treatment of HT I, plasma tyrosine elevation is a common finding as known from the other hypertyrosinemias.

PATIENTS AND METHODS

With elevated tyrosine as suspected pathogenic factor in the development of cognitive deficits, we here investigated tyrosine in the cerebrospinal fluid (CSF) and serotonergic and dopaminergic neurotransmitter levels in three patients with HT I during long-term treatment with Nitisinone. In addition, Nitisinone concentrations in plasma and CSF were measured. We also assessed psychomotor and cognitive development by standardized test systems and brain morphology by magnetic resonance imaging.

RESULTS

All patients presented with high tyrosine concentrations in CSF correlating with increased plasma tyrosine levels and a reduced CSF serotonin turnover. MRI revealed no structural abnormalities in the brain. All patients presented with either impaired cognitive development or behavioural abnormalities.

CONCLUSIONS

We here outline the need to further study the exact pathogenic mechanisms responsible for the neurotransmitter changes observed in HT type I in order to possibly prevent cognitive dysfunction. Nitisinone has significantly improved outcome and quality of life in HT type I; however, it is also accompanied by elevated plasma and CSF tyrosine. Further studies are essential to identify the necessary dietary tyrosine restriction and the optimal Nitisinone dose.

[Determination of nabumetone and 6-methoxy-2-naphthylacetic acid in plasma using HPLC with UV and MS detection]

The study aimed to establish and validate an analytical method for the determination of nabumetone and 6-methoxy-2-naphthylacetic acid (6-MNA) in human plasma after a single therapeutic dose of the drug. Two methods based on HPLC with UV and MS detection were compared. Optimal results in sample preparation were achieved using solid phase extraction. The recovery reached approximately 84% and 86-90% for nabumetone and 6-MNA, respectively. A reverse C18 column was used for HPLC separation of the analytes. The limit of UV detection was 50 nM and 0.1 microM for 6-MNA and nabumetone, respectively. The limit of MS detection was 1 microM and 0.5 microM for 6-MNA and nabumetone, respectively. Precision ranged between 4.2-14.4% and 4.6-8.5% using UV and MS detection for nabumetone, respectively. The respective values for 6-MNA were 2.4-12.5% and 2.1-9.4%. Accuracy ranged between 93.4-109.6% in UV detection and 86.2-107.9% using UV and MS detection for nabumetone, respectively. The respective values for 6-MNA were 87.8-107.4% and 86.3-106.4%. The method was subsequently applied to determine the pharmacokinetic parameters of nabumetone and 6-MNA in a group of 24 healthy volunteers.

[High digoxin serum levels in an elderly patient for the endogenous digoxin-like immunoreactive substances. A case report]

Digoxin is typically prescribed in the treatment of heart failure. Its limited therapeutic range requires systematic monitoring of plasmatic concentration through immunoreactive tests. Laboratory results, however, can be altered by the presence of digoxin-like immunoreactive factors (DLIF) which are released in all clinical conditions involving volemic expansion.

CASE REPORT

An 86-year-old woman arrived in emergency with severe dyspnoea, atrial flutter and a medical history of ischemic cardiopathy. The patient was treated with ACE inhibitor, furosemide, spironolactone and digoxin. The first lab test for digoxin showed levels of digoxin of 7.05 ng/ml. Although the patient did not show any clinical evidence of digital intoxication nor was she treated with drugs which might interfere with digoxin kinetics and even if she had markers of renal function within clinical limits, digoxin was suspended and a treatment was initiated with 0.9% NaCl solution and furosemide. The second lab test showed levels of digoxin of 8.38 ng/ml. A possible interference of DLIF with immunoreactive tests was therefore assumed.

MATERIALS AND METHODS

The patient's serum was ultrafiltered and centrifugated to remove possible DLIF; subsequently, the measurement of digoxin levels was repeated. As a result, the digoxin level decreased to 0.25 ng/ml.

CONCLUSIONS

DLIF increase in several diseases, including heart failure, end-stage renal disease, pre-eclampsy and acromegaly. High digoxin levels in a patient who does not show any symptoms of digital intoxication should lead to suspect the presence of these factors and to preventively determine DLIF in serum so as not to incur the risk of suspending an important treatment like digoxin in heart failure.

Effect of food on the pharmacokinetic profile of etamicastat (BIA 5-453)

BACKGROUND

Etamicastat is a novel, potent, and reversible peripheral dopamine-β-hydroxylase inhibitor that has been administered orally at doses up to 600 mg once daily for 10 days to male healthy volunteers and appears to be well tolerated.

OBJECTIVE

The aim of this study was to investigate the effect of food on the pharmacokinetics of etamicastat.

MATERIAL AND METHODS

A single-center, open-label, randomized, two-way crossover study in 12 healthy male subjects was performed. Subjects were administered a single dose of etamicastat 200 mg following either a standard high-fat and high-calorie content meal (test) or 10 hours of fasting (reference). The statistical method for testing the effect of food on the pharmacokinetic parameters of interest was based upon the 90% confidence interval (CI) for the test/reference geometric mean ratio (GMR). The parameters of interest were maximum plasma concentration (C(max)), area under the plasma concentration-time curve (AUC) from time zero to the last measurable concentration (AUC(last)), and AUC from time zero to infinity (AUC(∞)). Bioequivalence was assumed when the 90% CI fell within the recommended acceptance interval (80, 125).

RESULTS

Etamicastat C(max), AUC(last), and AUC(∞) were 229 ng/mL, 1856 ng · h/mL, and 2238 ng · h/mL, respectively, following etamicastat in the fasting, and 166 ng/mL, 1737 ng · h/mL, and 2119 ng · h/mL, respectively, following etamicastat in the fed condition. Etamicastat test/reference GMR was 72.27% (90% CI 64.98, 80.38) for C(max), 93.59% (90% CI 89.28, 98.11) for AUC(last), and 96.47% (90% CI 91.67, 101.53) for AUC(∞). Time to C(max) was prolonged by the presence of food (p < 0.001). The C(max), AUC(last), and AUC(∞) values of the inactive metabolite BIA 5-961 were 275 ng/mL, 1827 ng · h/mL, and 2009 ng · h/mL, respectively, in the fasting, and 172 ng/mL, 1450 ng · h/mL, and 1677 ng · h/mL, respectively, in the fed condition. BIA 5-961 test/reference GMR was 62.42% (90% CI 56.77, 68.63) for C(max), 79.41% (90% CI 56.77, 68.63) for AUC(last), and 83.47% (90% CI 76.62, 90.93) for AUC(∞). A total of six mild to moderate unspecific adverse events were reported by four subjects. There was no clinically significant abnormality in laboratory assessments.

CONCLUSION

Etamicastat was well tolerated. The C(max) of etamicastat decreased 28% following oral administration of etamicastat in the presence of food, while AUC remained within the pre-defined acceptance interval. The delay in absorption and decrease in peak exposure of etamicastat is not clinically significant, and therefore etamicastat could be administered without regard to meals.

TRIAL REGISTRATION

EudraCT No. 2007-006530-33.

Alteration in the plasma concentration of a DAAO inhibitor, 3-methylpyrazole-5-carboxylic acid, in the ketamine-treated rats and the influence on the pharmacokinetics of plasma D-tryptophan

A determination method for 3-methylpyrazole-5-carboxylic acid (MPC), an inhibitor of D-amino acid oxidase (DAAO), in rat plasma was developed by using high-performance liquid chromatography-mass spectrometry (LC-MS). The structural isomer of MPC, 3-methylpyrazole-4-carboxylic acid, was used as an internal standard, and the intra- and inter-day accuracies and precisions were satisfactory for the determination of plasma MPC.Next, the LC-MS method was applied to determine the plasma MPC concentration in ketamine (Ket)-treated rats after intraperitoneal administration of MPC (5.0 or 50 mg·kg(-1)). The C(max) value of plasma MPC concentration in the Ket-treated rats was significantly higher than that in the control group when a high dose of MPC (50 mg·kg(-1)) was administered. In addition, it was found that plasma D-tryptophan (D-Trp) concentration in Ket-treated rats administered D-Trp was not significantly increased by MPC, suggesting that the DAAO-inhibitory effect of MPC is attenuated in Ket-treated rats.

Serum asymmetric dimethylarginine levels in normotensive obese individuals

BACKGROUND

Obesity is associated with an increased risk of developing insulin resistance, hyperinsulinemia, glucose intolerance, dyslipidemia, hypertension, premature atherosclerosis, and coronary artery disease. This study is designed to compare serum asymmetric dimethylarginine (ADMA) levels between obese individuals and controls.

MATERIAL/METHODS

Fifty volunteers, 30 obese (13 men; mean age, 40±11 years) and 20 healthy controls (13 men; mean age, 44±10 years) were enrolled to this study. Measurement of ADMA was accomplished by high performance liquid chromatography.

RESULTS

The mean body mass index of the obese group was significantly higher than that of the control group (35±4 vs 26±3 kg/m2; P=.001). The mean waist circumference of the obese subjects was also significantly higher compared with controls (111±11 vs 93±10 cm; P=.001). No significant difference was found concerning age, sex, blood pressures, and biochemistry parameters. Serum ADMA levels were significantly higher in obese individuals compared with healthy controls (5.4±3.3 vs 3.1±1.8 µmol/L; P=.006). A weak but significant correlation was identified between serum ADMA concentration and the waist circumference (r=0.282, P=.047).

CONCLUSIONS

The results of the present study demonstrated that serum ADMA levels of normotensive obese individuals were significantly higher than healthy controls. Increased ADMA concentrations observed only in the obese group were deemed to be important regarding the development future of cardiovascular disease in the future.

A lipase inhibitor monoterpene and monoterpene glycosides from Monarda punctata

An 80% acetone extract of Monarda punctata showed an inhibitory effect on lipase activity in isolated mouse plasma in vitro and carvacrol was obtained as the active constituent. It had an IC₅₀ value of 4.07 mM invitro and suppressed elevations in blood triacylglycerol levels in olive oil-loaded mice. Furthermore, from the whole plant, 22 compounds were isolated. Six monoterpene glycosides, a flavone glucuronide, and other known compounds were identified based on the results of spectroscopic analyses.

Effect of CYP2C19 genotypes on the pharmacokinetic/pharmacodynamic relationship of rabeprazole after a single oral dose in healthy Chinese volunteers

AIMS

To explore the pharmacokinetic/pharmacodynamic relationship of rabeprazole and the role of CYP2C19 genotypes after a single oral dose in healthy Chinese volunteers by a population approach.

METHODS

Plasma concentration time profile data and intragastric pH values of 19 genotyped healthy male adults after a single oral dose of rabeprazole in an open label randomized fashion were used for this population analysis. Simulation technology was performed to examine the rabeprazole response in subjects with different CYP2C19 genotypes to further investigate the effect of acid inhibition.

RESULTS

The pharmacokinetics of rabeprazole was characterized by a two-compartment model with first order absorption and with an absorption lag-time. The results show that clearance of rabeprazole was affected by CYP2C19 genotypes (average clearances of homEM, hetEM, and PM were 13.9, 11.5, and 8.74 L·h(-1) respectively). An effect compartment with a sigmoidal Emax model was considered more rational for analyzing the relationship between rabeprazole concentrations and intragastric pH values. Simulated results suggest that rabeprazole 20 mg once daily for PMs is sufficient, but might be administered more frequently for other genotypes in treating gastro-esophageal reflux disease.

CONCLUSION

The CYP2C19 genotype played a considerable role in the pharmacokinetic characteristics of rabeprazole, and this might need to be taken into account for clinical use.

A sensitive and practical LC-MS/MS method for the determination of mizoribine in human serum and its bioequivalence study on Chinese healthy volunteers

A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the determination of mizoribine in human serum using thiamphenicol as internal standard (IS). The serum samples of mizoribine were precipitated with acetonitrile and separated by HPLC on a reversed phase C18 column with a mobile phase of 0.1% ammonium acetate water solution-methanol (47:53, v/v). Mizoribine and IS were detected in the multiple reaction monitoring mode with precursor/product ion transitions of m/z 258.2/126.0 and 354.1/185.2, respectively. The calibration curves were linear over the range of 0.02-2 microg mL(-1) for mizoribine. The limit of quantification (LOQ) was 0.02 microg mL(-1) with acceptable precision and accuracy. The validated method was successfully applied for the evaluation of a bioequivalence study on Chinese healthy volunteers. The main pharmacokinetics parameters after oral administration of 100 mg mizoribine test or reference formulation were as follows: Cmax (1.00 +/- 0.21), (1.00 +/- 0.22) microg mL(-1); AUC(0-infinity) (6.72 +/- 1.39), (6.48 +/- 1.44) microg h mL(-1); t1/2 (2.77 +/- 0.26), (2.66 +/- 0.29) h; tmax (2.95 +/- 0.78), (2.84 +/- 0.50) h.

Pharmacokinetics, disposition, and metabolism of [14C]-nebicapone in humans

OBJECTIVE

This study investigated the absorption, distribution, metabolism and excretion (ADME) of nebicapone [BIA 3-202; 1-(3,4-dihydroxy-5-nitrophenyl)-2-phenyl-ethanone], a reversible catechol-O-methyltransferase (COMT) inhibitor, in 4 healthy male subjects.

METHODS

This was a single center, open, non-placebo-controlled, single-group, and a single 200 mg dose study of [(14)C]-nebicapone (2.5 MBq). Blood, urine and faeces were collected up to 264 hours post-dose.

RESULTS

Collectively more than 22 metabolites were identified in plasma, urine and faeces, with 3-O-nebicapone-glucuronide (BIA 3-476) identified as the major metabolite. Plasma concentration-time profiles of [(14)C]-nebicapone demonstrated T(max) (h) 1.25+/-0.65, t(1/2) (h) 134.55+/-25.67, C(max) (ng-eq/g) 19647.02+/-4930.20, AUC(0-t) (h.ng-eq/g) 161735.51+/-9224.66, AUC(0-infinity) (h.ng-eq/g) 199603.30+/-16854.08, and for whole blood T(max) 1.00+/-0.41, t(1/2) 32.98+/-22.82, AUC(0-t) 35539.23+/-13664.87, AUC(0-infinity) 36970.64+/-14559.17. Plasma pharmacokinetics of nebicapone demonstrated T(max) (h) 1.00+/-0.41, t(1/2) (h) 2.34+/-0.51; C(max) (ng-eq/g) 12650.00+/-2898.85, AUC(0-t) (h.ng-eq/g) 18719.96+/-734.18, AUC(0-infinity) (h.ng-eq/g) 18392.12+/-753.81; BIA 3-476 demonstrated T(max) 1.25+/-0.50, t(1/2) 3.47+/-0.68; C(max) 15250+/-2563.20, AUC(0-t) 53810.61+/-7358.81, AUC(0-infinity) 54541.21+/-7135.70; 3-O-methyl-nebicapone (BIA 3-270) demonstrated T(max) 21.01+/-6.01, t(1/2) 103.43+/-6.01; C(max) 286.25+/-20.48, AUC(0-t) 27641.89+/-4569.99, AUC(0-infinity) 36968.12+/-4294.42.

CONCLUSIONS

Nebicapone and BIA 3-476 accounted for most early phase circulating nebicapone-derived moieties, have limited circulating cell association, peak concentrations shortly after dosing, and short body residence. In longer terminal half-life phases low concentrations of BIA 3-270 predominate. While about 70% of the dose was eliminated in the urine as BIA 3-476, < 1% of the dose was excreted as unchanged nebicapone. Faecal excretion accounted for 17.3% administered dose. On average, the total recovery of 88.6% of the radioactivity suggested no worrisome retention of drug derived material following a single 200 mg administration of nebicapone to healthy volunteers. The treatment was very well tolerated with no reported adverse events.

Determination of the gamma-secretase inhibitor MK-0752 in human plasma by online extraction and electrospray tandem mass spectrometry (HTLC-ESI-MS/MS)

A sensitive and rapid HTLC-ESI-MS/MS method with an advanced online sample preparation was developed for determination of the gamma-secretase inhibitor MK-0752 in human plasma using an internal standard. Plasma samples (100 microL) were diluted and injected directly onto an online extraction column (Cohesive Cyclone MAX 0.5 mm x 50 mm, > 30 microm), the sample matrix was washed out with an aqueous solution, and retained analytes were eluted out and transferred directly to the analytical column (Phenomenex Gemini 3 micron C18 110A, 50 mm x 2.0 mm at 50 degrees C) for separation using a gradient mobile phase. The eluted analytes were then detected on an API-3000 LC-MS/MS System with ESI and a negative multiple reaction monitoring mode. The monitored ion transitions were m/z 441-->175 for MK-0752 and 496-->175 for the internal standard. Online extraction recoveries were 81%. The method was validated and was linear in the range of 0.05-50 microg/mL. Within-day and between-day precisions were<8.6%, and accuracies were 0.7 and 7.1%. This method was applied to the measurement of plasma MK-0752 levels in a Phase I study of pediatric patients with recurrent or refractory brain tumors.

Probenecid treatment enhances retinal and brain delivery of N-4-benzoylaminophenylsulfonylglycine: an anionic aldose reductase inhibitor

Anion efflux transporters are expected to minimize target tissue delivery of N-[4-(benzoylaminophenyl)sulfonyl]glycine (BAPSG), a novel carboxylic acid aldose reductase inhibitor, which exists as a monocarboxylate anion at physiological conditions. Therefore, the objective of this study was to determine whether BAPSG delivery to various eye tissues including the retina and the brain can be enhanced by probenecid, a competitive inhibitor of anion transporters. To determine the influence of probenecid on eye and brain distribution of BAPSG, probenecid was administered intraperitoneally (120 mg/kg body weight; i.p.) 20 min prior to BAPSG (50 mg/kg; i.p.) administration. Drug disposition in various eye tissues including the retina and the brain was determined at 15 min, 1, 2 and 4h after BAPSG dose in male Sprauge-Dawley rats. To determine whether probenecid alters plasma clearance of BAPSG, influence of probenecid (120 mg/kg; i.p.) on the plasma pharmacokinetics of intravenously administered BAPSG (15 mg/kg) was studied as well. Finally, the effect of probenecid co-administration on the ocular tissue distribution of BAPSG was assessed in rabbits following topical (eye drop) administration. Following pretreatment with probenecid in the rat study, retinal delivery at 1h was increased by about 11-fold (2580 ng/g vs. 244 ng/g; p<0.05). Further, following probenecid pretreatment, significant BAPSG levels were detectable in the brain (45 + or - 20 ng/g) at 1h, unlike controls where the drug was not detectable. Plasma concentrations, plasma elimination half-life, and total body clearance of intravenously administered BAPSG were not altered by i.p. probenecid pretreatment. In the topical dosing study, a significant decline in BAPSG delivery was observed in the iris-ciliary body but no significant changes were observed in other tissues of the anterior segment of the eye including tears. Thus, inhibition of anion transporters is a useful approach to elevate retinal and brain delivery of BAPSG.

Vascular Endothelial Growth Factor Induces Endothelin-1 Production via Matrix Metalloproteinase-2 Rather than Endothelin-Converting Enzyme-1

OBJECTIVE

To investigate the mechanism of vascular endothelial growth factor (VEGF)-induced endothelin-1 production in human umbilical vein endothelial cells (HUVECs).

METHODS

Endothelin-1 levels were measured in conditioned medium of women with preeclampsia HUVECs were treated with different concentrations of VEGF(165) and at various time intervals. Next, we measured endothelin-1 levels after HUVECs were also incubated with VEGF and endothelin-converting enzyme-1 (ECE-1) inhibitor or tissue inhibitors of matrix metalloproteinase-2 (TIMP-2). Additionally, the circulating levels of total and free VEGF, matrix metalloproteinase-2 (MMP-2), and endothelin-1 were measured in 20 preeclamptic patients and 20 healthy pregnant controls.

RESULTS

HUVECs treated with VEGF increased their endothelin-1 production in a concentration and time-dependent manner. The production of endothelin-1 was inhibited by TIMP-2, but not by the ECE-1 inhibitor. Total VEGF, MMP-2, and endothelin-1 concentrations were higher in preeclampsia and showed significant positive correlations between them.

CONCLUSION

These findings suggest that VEGF-induced endothelin-1 production might be mediated by MMP-2 rather than by ECE-1 upregulation.

Hydrophilic interaction chromatography/tandem mass spectrometry for the simultaneous determination of three polar non-structurally related compounds, imipenem, cilastatin and an investigational beta-lactamase inhibitor, MK-4698, in biological matrices

A method coupling hydrophilic interaction chromatography (HILIC) with tandem mass spectrometry (MS/MS) has been developed for the simultaneous determination of three polar non-structurally related compounds--a carbapenem antibiotic, imipenem (IMP), a renal dehydropeptidase inhibitor, cilastatin (CIL), and an investigational beta-lactamase inhibitor, MK-4698 (BLI), in rat plasma, monkey plasma and mouse blood. The analytes were extracted through protein precipitation, chromatographed on a Waters Atlantis HILIC column, and detected on a Sciex API4000 mass spectrometer using a Turbo-Ion Spray ion source in positive ionization mode following multiple-reaction monitoring (MRM). The assay dynamic range was 0.1-100 microg/mL for IMP, CIL and BLI, respectively, using a total of 20-25 microL biologic samples, and the total HPLC/MS/MS run time was 4 min/injection. The assay was found to be sensitive, selective and reproducible. The challenges, namely, sample stability, blood sample processing, matrix effect in monkey study samples, and dilution re-assays for the limited mouse blood samples, are resolved and discussed. This technique allowed rapid analysis of polar compounds in biologic matrixes with satisfactory chromatographic retention and increased throughput.