Quantitation of amyloid beta peptides in CSF by surface enhanced MALDI-TOF.

Alzheimer's disease is characterized by the deposition of amyloid plaques in the brain. The major components of these plaques are β-amyloid (Aβ) peptides. The CSF concentration of these peptides can therefore provide a valuable biomarker for potentially predicting the state of disease and/or monitoring the efficacy of a drug aiming to inhibit the formation of amyloid plaques.

Patient-specific measures of a biomarker for the generation of individual reference intervals: hemoglobin as example.

Although hemoglobin concentration measurement is among the most commonly performed blood tests, the description of global population parameters, heterogeneous factors, and within-subject variations in patients with disease remains incomplete. As absolute action values are being published in the medical literature and by government healthcare agencies, these measures are important to define patient-specific ranges of biomarkers. Here, a global clinical trial data set composed of 1,537,932 hemoglobin values from 416,374 patients and 372 clinical indications was generated over 2 years by automated analyzers in a global network of 5 laboratories.

Analytical validation of a highly sensitive microparticle-based immunoassay for the quantitation of IL-13 in human serum using the Erenna immunoassay system.

IL-13 is a Th2 cytokine that has been shown to be an important mediator of airway inflammation contributing to asthma lesions. Given its proposed role in asthma, measurements of this cytokine in serum may provide insights into disease mechanisms, progression and pharmacodynamic effects of IL-13 targeted therapeutics. However, current commercially available ELISA immunoassays are frequently unable to detect baseline concentrations of IL-13 in serum from healthy individuals, which are below the limit of detection.

Safety, pharmacokinetics, and pharmacodynamics of single doses of LXR-623, a novel liver X-receptor agonist, in healthy participants.

Liver X-receptor (LXR) agonists have been postulated to enhance reverse cholesterol transport (RCT), a process believed to shuttle cholesterol from the periphery back to the liver. Enhancing RCT via the upregulation of cholesterol transporters such as the adenosine triphosphate-binding cassettes ABCA1 and ABCG1 could therefore inhibit the progression of atherosclerosis. LXR-623 is a synthetic ligand for LXRs alpha and beta that has shown promise in animal models of atherosclerosis.

Analytical validation of genotyping assays in the biomarker laboratory.

High-throughput, whole-genome association studies conducted in various diseases and therapeutic settings are identifying an increasing number of single nucleotide polymorphisms that may predict patient responses and ultimately guide therapeutic decision-making. In order to confirm the candidate genetic markers emerging from these studies, there is a commensurate need for pharmacogenomic laboratories to design and analytically validate targeted genotyping assays capable of rapidly querying the identified individual single nucleotide polymorphisms of interest in large confirmatory clinical studies. In recent years, a number of increasingly complex technologies have been applied to the qualitative and semi-quantitative analysis of polymorphisms and mutations in DNA.

Automated on-line SPE LC-MS/MS method to quantitate 6beta-hydroxycortisol and cortisol in human urine: use of the 6beta-hydroxycortisol to cortisol ratio as an indicator of CYP3A4 activity.

A sensitive method for quantitation of urinary 6beta-hydroxycortisol (6beta-HC) and cortisol using on-line SPE and LC-MS/MS was developed and validated. Human urine samples were injected directly onto an on-line solid phase extraction apparatus, Prospekt-2, followed by HPLC separation and electrospray triple quadrupole LC-MS/MS detection. The inter-day precision for the 6beta-HC:cortisol ratio was 7-9%.

Method validation and measurement of biomarkers in nonclinical and clinical samples in drug development: a conference report.

Biomarkers are increasingly used in drug development to aid scientific and clinical decisions regarding the progress of candidate and marketed therapeutics. Biomarkers can improve the understanding of diseases as well as therapeutic and off-target effects of drugs. Early implementation of biomarker strategies thus promises to reduce costs and time-to-market as drugs proceed through increasingly costly and complex clinical development programs.

Pharmacokinetics and pharmacodynamics of the vasopeptidase inhibitor, omapatrilat in healthy subjects.

Aims: To determine the pharmacokinetics, pharmacodynamics and tolerability of omapatrilat, a vasopeptidase inhibitor, in healthy subjects.

Methods: The effects of oral omapatrilat were evaluated in healthy men in two double-blind, placebo-controlled, dose-escalation trials. In a single-dose study, subjects received omapatrilat in doses of 2.

Omapatrilat: neurohormonal and pharmacodynamic profile when administered with furosemide.

Pharmacodynamic effects of combination therapy with omapatrilat and furosemide were evaluated. Two groups of 13 healthy subjects each received furosemide 20 mg dailyfor 15 days coadministered with either placebo on days 6 to 15 or omapatrilat 10 mg on days 6 to 10 and 25 mg on days 11 to 15. In the omapatrilat group, urinary excretion of atrial natriuretic peptide increased, and greater blood pressure reductions were seen compared with placebo.

Pharmacodynamics and pharmacokinetics of omapatrilat in heart failure.

The purpose of this study was to determine the pharmacodynamics and pharmacokinetics of omapatrilat, administered orally (25 mg) or intravenously (10 mg) in 19 New York Heart Association class II and class III congestive heart failure (CHF) patients versus 17 healthy controls matched for age, race, gender, and weight. The plasma concentrations of atrial natriuretic peptide (ANP) increased by approximately 20% and 30% in CHF and control subjects, respectively, at 4 hours after intravenous or oral omapatrilat administration. Similar elevation in the cyclic guanosine monophosphate concentration (25% to 35%) and ANP urinary excretion (21 ng/24 h to 22 ng/24 h) was seen in all treatment groups after omapatrilat administration.

Omapatrilat versus lisinopril: efficacy and neurohormonal profile in salt-sensitive hypertensive patients.

Omapatrilat, a vasopeptidase inhibitor, simultaneously inhibits neutral endopeptidase and ACE. The efficacy and hormonal profile of omapatrilat and lisinopril were compared in salt-sensitive hypertensive patients. On enrollment, antihypertensive medications were withdrawn, and patients received a single-blind placebo.

Effects of omapatrilat on pharmacodynamic biomarkers of neutral endopeptidase and Angiotensin-converting enzyme activity in humans.

Vasopeptidase inhibition is a new concept in blood pressure management. A single molecule simultaneously inhibits two enzymes that regulate cardiovascular function: neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE)[1]. Development of vasopeptidase inhibitors stemmed from the need for new and more efficacious antihypertensive agents that not only reduce blood pressure but also treat hypertension as part of a larger syndrome involving endothelial dysfunction [2].

Omapatrilat in patients with hepatic cirrhosis. Pharmacodynamics and pharmacokinetics.

Objective: The pharmacodynamics and pharmacokinetics of omapatrilat, a member of a new class of cardiovascular compounds, the vasopeptidase inhibitors, were evaluated in subjects with hepatic cirrhosis (n = 10) and in healthy subjects (n = 10) matched for age, weight, gender and smoking history.

Methods: All subjects received omapatrilat 25 mg orally once daily for 14 days. Plasma renin and urinary atrial natriuretic peptide (ANP) levels were measured to assess the effect of omapatrilat on cirrhotic subjects.

Effects of age and gender on the pharmacodynamics of omapatrilat in healthy volunteers.

Omapatrilat is the most clinically advanced member of a new class of cardiovascular drugs, vasopeptidase inhibitors. Omapatrilat is a single molecule that simultaneously inhibits neutral endopeptidase and angiotensin-converting enzyme, thus preserving vasodilator peptides and inhibiting production of the vasoconstrictor angiotensin II. In healthy male volunteers, omapatrilat decreased blood pressure while being generally well tolerated, with no serious adverse events.

Pharmacodynamics and Pharmacokinetics of Irbesartan in Patients With Mild to Moderate Hypertension.

BACKGROUND: The pharmacodynamics (plasma angiotensin II [AII], plasma renin activity [PRA], renal function, blood pressure [BP], urinary excretion of major metabolites of prostacyclin [PGI(2)-M], and thromboxane A(2) [TXA(2)-M]) and pharmacokinetics of irbesartan were assessed in hypertensive patients. METHODS AND RESULTS: Twenty-four white patients with seated diastolic blood pressure 95 to 110 mmHg were randomized to double-blind irbesartan 300 mg or placebo once daily for 4 weeks, following a placebo lead-in. Irbesartan-treated patients had significantly greater 24-hour area under the curve values for mean change from baseline in AII and PRA versus placebo-treated patients on day B15 (AII [pg |mZ h/mL]: 261 +/- 515 vs 12 +/- 51; PRA [(ng/mL/h); h]:74 +/-162 vs -2 +/-14; P values >.

Pharmacodynamic effects of dual neutral endopeptidase-angiotensin-converting enzyme inhibition versus angiotensin-converting enzyme inhibition in humans.

Background: There is currently no clear evidence that dual neutral endopeptidase-angiotensin-converting enzyme inhibitors have effects on angiotensin-converting enzyme, renin, or blood pressure that are different from specific angiotensin-converting enzyme inhibitors in humans.

Methods And Results: In a double-blind, placebo-controlled crossover study, single oral doses of the dual neutral endopeptidase-angiotensin-converting enzyme inhibitor, 10 mg BMS-186716 and the angiotensin-converting enzyme inhibitor fosinopril (20 mg) were administered to 9 normotensive subjects with induced mild sodium depletion. Values for area under the time curve from 0 to 24 hours [AUC(0-24)] for the plasma angiotensin II/angiotensin I ratio and for angiotensin II were similar for 10 mg BMS-186716 and 20 mg fosinopril.

Determination of metformin in plasma by high-performance liquid chromatography after ultrafiltration.

A rapid high-performance liquid chromatography (HPLC) method was developed for determination of metformin, an oral antidiabetic agent, in plasma. Sample preparation entailed a 30-min centrifugation of plasma through a micron filter with direct injection of the protein-free ultrafiltrate into an HPLC system consisting of a cation-exchange extraction column (7.5x4.

Myocardial calcium-independent phospholipase A2 activity during global ischemia in isolated rabbit hearts.

Objectives: To study calcium-independent phospholipase A2 activity during global ischemia in isolated rabbit hearts by measuring the hydrolysis of the endogenous choline phospholipids.

Methods: Langendorff perfused rabbit hearts were exposed to global ischemia for 15 or 60 min, or control perfusion for the same length of time. The hearts were then rapidly frozen in liquid nitrogen and lyophilized.

Implications of the prognostic importance of exercise-induced thromboxane formation in survivors of an acute myocardial infarction.

Thirty-two patients with acute myocardial infarction performed an exercise stress test one month after hospital discharge. The in vivo formation of thromboxane and prostacyclin formation before and during the exercise stress test was analyzed with gas chromatography-mass spectrometry of the in vivo formed metabolites 2,3-dinor-TxB2 and 2,3-dinor-6-keto-PGF1 alpha. Patients with a significant increase in thromboxane formation (> 30%) during exercise (P < 0.

Characterization of rabbit myocardial phospholipase A2 activity using endogenous phospholipid substrates.

We have developed an assay for studying myocardial phospholipase A2 activity by measuring accumulation of lysophospholipids resulting from hydrolysis of the endogenous choline glycerophospholipid pool. This assay was used to characterize phospholipase A2 activity in rabbit myocardium. Lyophilized rabbit myocardium was incubated at 37 degrees C in Tris-HCl buffer containing either ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA)/EDTA or calcium, and palmitoyl-lysophosphatidylcholine (P-LPC), oleoyl-LPC, stearoyl-LPC, and 16:0-lysoplasmenylcholine were measured using a recently developed HPLC method.

Effects of endogenous and exogenous lysophosphatidylcholine in isolated perfused rat hearts.

In isolated Langendorff perfused rat hearts, treatment with exogenous palmitoyl-lysophosphatidylcholine (P-LPC; 3-50 microM) under normoxic conditions, resulted in reduced heart rate (HR), coronary flow (CF) and contractile function. After 30 min Krebs perfusion, following P-LPC infusion, HR and CF remained reduced and contractile function continued to deteriorate. End diastolic pressure (EDP) and lactate dehydrogenase (LDH) release in LPC treated hearts were significantly increased from controls.

Peroxisomal chain-shortening of thromboxane B2: evidence for impaired degradation of thromboxane B2 in Zellweger syndrome.

We have shown that rat liver peroxisomes can chain-shorten prostaglandins to dinor- and tetranor-metabolites. In a recent in vivo study we could demonstrate that peroxisomes are of major importance for chain-shortening of prostaglandin F2 alpha in humans (1991, Diczfalusy et al. J.

Plasma growth factor activity and cardiac wall thickness.

Objectives: The aim of this study was to investigate the growth factor activity in plasma (GFAP) in hypertension, and the correlation of GFAP to blood pressure levels, cardiac structural changes and platelet activation at rest and during exercise.

Subjects: Fifteen untreated hypertensive subjects and 15 normotensive controls were recruited from a blood pressure screening programme.

Interventions: GFAP before and after 30 min of strenuous exercise was analysed as the ability of patient or control plasma to stimulate incorporation of 3H-thymidine in cultured human smooth muscle cells.

Evidence of increased platelet activation after thrombolysis in patients with acute myocardial infarction.

Objective: To assess platelet activation after thrombolysis in patients with acute myocardial infarction.

Design: Platelet function was assessed by measurement of the in vivo synthesis of thromboxane by gas chromatography-mass spectrometry of thromboxane's major urinary metabolite, 2,3-dinor-thromboxane-B2.

Setting: Coronary care unit of Huddinge University Hospital.