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At least 433 records · Page 24Linked to original sources

PubMed2005

Simplified ultraviolet liquid chromatographic method for determination of sertindole, dehydrosertindole and norsertindole, in human plasma.

An ultra-violet high-performance liquid chromatographic method was developed for the determination of sertindole, an atypical antipsychotic drug and its main metabolites dehydrosertindole and norsertindole, in human plasma. With a small sample volume, after a single-step liquid-liquid extraction, the compounds were separated on a reversed-phase XTerra RP(18) column, eluted with 45% of acetonitrile and 55% of ammonium acetate buffer (0.05 M, adjusted pH 8) and detected at 256 nm within 11 min. This method shows a good linearity for plasma concentration between 5-100 ng/ml and 100-1000 ng/ml, a good precision (inter and intra day CV < 11%) and a good inter-assay accuracy (bias < 11%). The limit of quantification concentration was 5 ng/ml. The absolute recovery of sertindole was higher than 99%. This rapid and sensitive method could be used for therapeutic drug monitoring as well as for overdose management.

Antipsychotic Agents↗

PubMed2005

Determination of the novel non-peptidic HIV-protease inhibitor tipranavir by HPLC-UV after solid-phase extraction.

An HPLC method previously described for the assay of amprenavir (APV), ritonavir (RTV), indinavir (IDV), saquinavir (SQV), nelfinavir (NFV), lopinavir (LPV), atazanavir (ATV), nevirapine (NVP) and efavirenz (EFV) can be also conveniently applied, with minor gradient program adjustment, for the determination of the novel non-peptidic HIV protease inhibitor tipranavir (TPV) in human plasma, by off-line solid-phase extraction (SPE) followed by HPLC coupled with UV-diode array detection (DAD). After viral inactivation by heat, the plasma is diluted with phosphate buffer (pH 7), and subjected to a SPE on a C18 cartridge. Matrix components are eliminated with a solution of 0.1% H3PO4 solution neutralised to pH 7, and TPV is eluted with MeOH. The resulting eluate is evaporated and reconstituted in 100 microl MeOH/H2O 50/50. A 40 microl volume is injected onto a Nucleosil C18 AB column and TPV is analysed by UV detection at 201 nm using a gradient elution program constituted of MeCN and phosphate buffer adjusted to pH 5.12 and containing 0.02% sodium heptanesulfonate. The calibration curves are linear up to 75 microg/ml, with a lower limit of quantification of 0.125 microg/ml. The mean absolute recovery of TPV is 77.1+/-4.0%. The method is precise with mean inter-day coefficient of variations (CVs) within 2.2-3.4%, and accurate (range of inter-day deviations from 0.7 to 1.2%). The method has been validated and is currently applied to the monitoring of TPV plasma levels in HIV patients.

Calibration↗

PubMed2006

Simple determination of the HIV protease inhibitor atazanavir in human plasma by high-performance liquid chromatography with UV detection.

A simple high-performance liquid chromatography method for the determination of the human immunodeficiency virus protease inhibitor atazanavir in human plasma samples was developed and validated. The method involved a rapid and simple solid-phase extraction of atazanavir using Oasis HLB 1cc cartridges, an isocratic reversed-phase liquid chromatography on an XTerra RP18 (150mmx4.6mm, 3.5microm) column, and ultraviolet detection at 203nm. The mobile phase consisted of phosphate buffer (pH 6, 52.5mM) and acetonitrile (43:57, v/v). Up to 48 samples could be measured in one day since the run-time of one sample was 30min. The assay was linear from 0.04 to 10microg/ml with a lower limit of quantification of 0.04microg/ml. The mean absolute recovery of ATV was 98.1%. The method was precise, with both intra-day and inter-day coefficients of variation < or =3.0%, and accurate (deviations ranged from -3.0% to 4.5% and from -3.6% to 4.7% for intra-day and inter-day analysis, respectively). There was no interference from 35 tested potentially co-administrated drugs. This method provides a simple, sensitive, precise and reproducible assay for the therapeutic drug monitoring of atazanavir in clinical routine of laboratories with standard equipment.

Atazanavir Sulfate↗

PubMed2002

Determination of fluoxetine enantiomers in rat plasma by pre-column fluorescence derivatization and column-switching high-performance liquid chromatography.

A column-switching HPLC method employing both octadecylsilica (ODS) and chiral columns with fluorescence detection was developed for the determination of enantiomer of fluoxetine (FLX), an antidepressant drug, in rat plasma. Racemic FLX was derivatized with a fluorescent reagent, 4-(N-chloroformylmethyl-N-methyl)amino-7-nitro-2,1,3-benzoxadiazole (NBD-COCl) or 4-(N-chloroformylmethyl-N-methyl)amino-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole (DBD-COCl) and the enantiomeric separation of the resultant derivatives was examined on an amylose-based chiral column (CHIRALPAK AD-RH) in the reversed-phase mode. The derivative with NBD-COCl (NBD-FLX) showed a sufficient separation factor (a) and resolution (Rs) compared with that with DBD-COCl. Thus, FLX was derivatized with NBD-COCl and the resultant NBD-FLX was first quantified on the ODS column and then introduced to the CHIRALPAK AD-RH column via a six-port switching valve to examine the enantiomeric ratio. The intra- and inter-day accuracy (97.6-112.7%) and precision (1.47-10.60%) were satisfactory in the range 10-1000 nM FLX and the limit of quantification was approximately 10 nM. The absolute recoveries of FLX with hexane from rat plasma were in the range 87.5-92.2% (n = 3). The method was applied to determine FLX enantiomers in the plasma of rats administered FLX orally, and it was shown that the R-isomer was eliminated faster than the S-isomer.

Animals↗

PubMed2004

[A software tool for analysis and quantification of regional pulmonary ventilation using dynamic hyperpolarised-(3)He-MRI].

PURPOSE: (3)He-MRI is able to visualize the regional distribution of lung ventilation with a temporal and spatial resolution so far unmatched by any other technique. The aim of the study was the development of a new software tool for quantification of dynamic ventilation parameters in absolute physical units. MATERIALS AND METHODS: During continuous breathing, a bolus of hyperpolarized (3)He (300 ml) was applied at inspiration and a series of 168 coronal projection images simultaneously acquired using a 2D FLASH-sequence. Postprocessing software was developed to analyze the (3)He distribution in the lung. After correction for lung motion, several ventilation parameters (rise time, delay time, (3)He amount and (3)He peak flow) were calculated. Due to normalization of signal intensities, these parameters are presented in absolute physical units. The data sets were analyzed on a ROI basis as well as on a pixel-by-pixel basis. RESULTS: Using the developed software, the measurements were analyzed in 6 lung-healthy volunteers, in one patient after lung transplantation, and in one patient with lung emphysema. The volunteers' parameter maps of the pixel-based analysis showed an almost homogeneous distribution of the ventilation parameters within the lung. In the parameter maps of both patients, regions with poor ventilation were observed. CONCLUSION: The developed software permits an objective and quantitative analysis of regional lung ventilation in absolute physical units. The clinical significance of the parameters, however, has to be determined in larger clinical studies. The software may become valuable in grading and following pulmonary function as well as in monitoring any therapy.

Aged↗

PubMed1995

Imaging of the heart by MRI and PET.

This review article describes the clinical usefulness and future potential of two new methods for the imaging of the heart, which have recently also become available outside research laboratories. These methods are magnetic resonance imaging (MRI) and positron emission tomography (PET). MRI is the most rapidly increasing imaging modality in medicine today. The moving heart forms a challenge to conventionally rather slow MRI-techniques. Techniques based on ECG-gating have been mandatory in making cardiac cine-MRI possible. Even though MRI provides accurate and quantitative information of the heart, conventional methods are time-consuming, confined to special laboratories, and rather expensive. Therefore, the clinical use of cardiac MRI is, in many laboratories, limited to cases in which echocardiography does not provide adequate information (e.g. pulmonary circulation) or when the patient is not willing to have transoesophageal echocardiography for better visibility. MRI is also used instead of or to complement invasive angiography to study large vessels, and it provides excellent information on paracardiac masses. Cardiac MRI is developing rapidly and within the next few years it is likely to have a profound impact on cardiac imaging. This is based on its noninvasive nature and on the comprehensive anatomic (including coronary arteries), functional, flow, perfusion and possibly also metabolic information it has the potential to provide in a manner not comparable to any other imaging method. PET is a nuclear medicine imaging modality that allows quantitative characterization of a variety of physiological and metabolic processes in vivo. Using positron-emitting flow tracers and analogues of metabolic substrates, regional myocardial blood flow, glucose and fatty acid metabolism and oxygen consumption can be studied noninvasively by PET in research as well as in clinical practice. For example, regional myocardial glucose utilization rates can be measured accurately by PET. This allows us to study the effects of nutritional interventions, hormonal and neural effects as well as disease processes on the glucose utilization of the human heart. PET is currently the only technique that permits noninvasive quantification of regional myocardial perfusion in absolute terms. Over the last decade, PET has also emerged as a clinically useful tool to study coronary artery disease and myocardial viability.

Heart↗

PubMed2006

Thin-layer chromatography analysis of human CYP3A-catalyzed testosterone 6beta-hydroxylation.

Testosterone and other steroid hormones have been studied as prototypic examples of endogenous substrates for hepatic cytochrome P450 (P450) enzymes. CYP3A enzymes from various species, including human, metabolize testosterone by a 6beta-hydroxylation reaction, which is unique to this P450 subfamily. A thin-layer chromatographic method is described for the determination of 6beta-hydroxytestosterone formed enzymatically by incubation of [14C]-testosterone with cDNA-expressed CYP3A enzymes or liver microsomes. 14C-labeled enzymatic products are applied to silica gel thin-layer plates, which are developed sequentially with methylene chloride:acetone (80:20) followed by chloroform, ethyl acetate, and absolute ethanol (80:20:14). Metabolite quantification is performed by autoradiography and liquid scintillation counting. This method is applicable to enzymatic studies for the determination of CYP3A-dependent testosterone 6beta-hydroxylation activity in both human and animal liver microsomes.

Autoradiography↗

PubMedDate not supplied

Absolute lung density in experimental canine pulmonary edema.

The noninvasive quantification of pulmonary edema could be of importance in patient management. We have developed a portable Compton-scatter densitometer capable of measuring density in the range of 0.1-1 g/cm3 independently of the chest wall. Change in lung density was investigated in 19 dogs with pulmonary edema induced by a combination of raised left atrial pressure and hemodilution. The increase in lung density correlated with the postmortem assessment of lung water (r = 0.862, p less than 0.01) and with hemodynamic indicators of pulmonary edema (r = 0.749, p less than 0.01). Subtracting the intravascular component of lung density did not improve the correlation with postmortem lung water (r = 0.850, p less than 0.01). The measurement of absolute lung density by a Compton-scatter technique may be a potentially useful method of quantifying pulmonary edema.

Absorptiometry, Photon↗

PubMed2026

Accurate quantification of canine mitochondrial DNA copy number from canine blood and brain samples.

Acute brain injury is difficult to evaluate in veterinary medicine and tools to investigate the potential involvement of mitochondrial involvement are limited. The brain is highly enriched in mitochondria and contains thousands of copies of mitochondrial DNA (mtDNA) per cell, but robust methods for quantifying mitochondrial DNA copy number (mtDNA-CN) in canine tissues are lacking. We describe the development of a quantitative real-time PCR assay for absolute measurement of mtDNA-CN which was validated in canine blood and brain tissue. To minimize amplification of nuclear mitochondrial insertion sequences (NumtS) and repetitive regions, species-specific oligonucleotide primers were designed following in silico genomic filtering. The assay was applied to a small pilot cohort comprising blood samples from dogs with and without acute brain injury (n = 4-6 per group) and cerebral cortex samples (n = 1 per group) to assess feasibility and biological plausibility. In non-brain injury dogs, blood mtDNA-CN ranged from 98 to 288 copies per nuclear genome (mean 193 ± 72), while values in brain-injured cases ranged from 163 to 228 copies per genome (mean 200 ± 33). Cerebral cortex samples exhibited higher mtDNA-CN than blood, consistent with known tissue-specific mitochondrial enrichment. In a single brain-injured case with serial sampling, mtDNA-CN increased over five days. This study presents a validated assay and pilot data for mtDNA-CN quantification in canine samples. While not powered for biomarker evaluation, this method may enable future studies of mitochondrial dynamics in canine brain injury and metabolic disease.

Animals↗

PubMed2000

Quantification of free mycophenolic acid by high-performance liquid chromatography-atmospheric pressure chemical ionisation tandem mass spectrometry.

To facilitate the investigation of free mycophenolic acid concentrations we developed a high-performance liquid chromatography tandem mass spectrometry method using indomethacin as an internal standard. Free drug was isolated from plasma samples (500 microl) using ultrafiltration. The analytes were extracted from the ultrafiltrate (200 microl) using C18 solid-phase extraction. Detection was by selected reactant monitoring of mycophenolic acid (m/z 318.9-->190.9) and the internal standard (m/z 356.0-->297.1) with an atmospheric pressure chemical ionisation interface. The total chromatographic analysis time was 12 min. The method was found to be linear over the range investigated, 2.5-200 microg/l (r>0.990, n=6). The relative recovery of the method for the control samples studied (7.5, 40.0 and 150 microg/l) ranged from 95 to 104%. The imprecision of the method, expressed in terms of intra- and inter-day coefficients of variation, was <8 and <9%, respectively. Further, analysis of pooled patient plasma produced an intra-day imprecision of 6.6%. The signal-to-noise ratio at the limit of quantification (2.5 microg/l) was approximately 5:1. The mean absolute recovery (n=6) of mycophenolic acid and the internal standard were 76.0+/-13.5% and 86.0+/-9.1%, respectively. The method reported provides an accurate and precise quantification of free mycophenolic acid over a wide analytical range and thus can be used for routine monitoring and pharmacokinetic studies.

Atmospheric Pressure↗

PubMed1994

Early detection of abnormal coronary flow reserve in asymptomatic men at high risk for coronary artery disease using positron emission tomography.

BACKGROUND: The objective of this study was to compare coronary flow reserve (CFR) as a measure of vascular integrity in asymptomatic middle-aged men with family history of coronary artery disease (CAD) and a high-risk lipid profile with men without risk factors for CAD using positron emission tomography (PET). Previous studies suggested that the assessment of CFR is a sensitive means to detect vascular abnormalities before angiographic appearance of CAD. N-13 ammonia PET scanning allows noninvasive evaluation of regional and global myocardial blood flow and thereby quantification of CFR. METHODS AND RESULTS: We used dynamic N-13 ammonia PET imaging in conjunction with intravenous adenosine to assess regional and global CFR in asymptomatic middle-aged men with high risk (group 1, n = 16) and men without any known risk factors (group 2, n = 11) for CAD. Group 1 patients were selected based on positive family history of CAD, one or more lipid abnormalities, and a normal stress test. No patient had history of diabetes or hypertension. A three-compartment tracer kinetic model developed and validated in our institution was used to calculate myocardial blood flow. Absolute myocardial blood flow (mL/100 g per minute) was calculated in five territories for each patient. CFR was defined as the ratio of blood flow during maximum pharmacological vasodilatation to blood flow at rest. Comparisons of CFR between the two groups of patients were performed. The mean age was similar between groups (group 1, 49.3 +/- 0.5 years; group 2, 48.1 +/- 8.7 years; P = NS). Group 1 had higher total cholesterol (mg/dL) (241 +/- 43 versus 173 +/- 34, P < .001), total cholesterol to high-density lipoprotein cholesterol ratio (6.4 +/- 1.6 versus 4.1 +/- 1.4, P < .001), and low-density lipoprotein cholesterol (mg/dL) (167 +/- 33 versus 107 +/- 32). No group 1 patient had evidence of ischemia by exercise ECG or exercise of pharmacological radionuclide perfusion studies. The mean global absolute myocardial blood flow at rest was not significantly different among groups (group 1, 76 +/- 18; group 2, 66 +/- 8; P = NS; (in mL/100 g per minute). However, blood flow after adenosine infusion was higher for group 2 (group 1, 217 +/- 56; group 2, 264 +/- 39; P < .001), which resulted in a larger CFR for group 2 (group 1, 2.93 +/- 0.86; group 2, 4.27 +/- 0.52; P < .001). Univariate linear regression analysis revealed significant negative correlation of CFR to total cholesterol (P < .05, r = -.41), low-density lipoprotein (P < .05, r = -.38), and total cholesterol to high-density lipoprotein cholesterol ratio (P < .05, r = -.47). CONCLUSIONS: Noninvasive quantification of absolute myocardial blood flow by N-13 ammonia PET allows the detection of abnormal vasodilatory response to intravenous adenosine in male patients with family history of CAD and high-risk lipid profiles. Early assessment of alterations of vascular reactivity to adenosine in relation to high-risk lipid profiles in asymptomatic men may allow early detection of preclinical atherosclerosis and may initiate modification and/or elimination of risk factors that may slow, retard, or even reverse the progression of CAD.

Adenosine↗

PubMed2005

Simultaneous determination of ZT-1 and its metabolite Huperzine A in plasma by high-performance liquid chromatography with ultraviolet detection.

ZT-1 is a novel acetylcholinesterase (AChE) inhibitor. It is rapidly transformed to Huperzine A (Hup A) in vitro. A simple and rapid HPLC-UV method for the simultaneous determination of ZT-1 and its metabolite Hup A in plasma is described. The chromatographic separations were achieved on a C(18) ODS column (250 mm x 4.6 mm ID) using methanol-1 mmol/L ammonium acetate (70:30,v/v) as mobile phase. The flow rate was 0.7 mL/min, the detection wavelength was 313 nm and the column temperature was kept at 35 degrees C. Plasma samples were prepared as rapidly as possible and extracted immediately with 5 mL of chloroform:iso-propyl alcohol mixture (v/v, 9:1). The retention times of ZT-1 and Huperzine A (Hup A) were 18.7 and 14.4 min, respectively. The mean absolute recoveries of two analytes were >90%. Quantification limits were all 0.02 nmol/mL for ZT-1 and Hup A. This analytical method was reliable and convenient procedure that meets the criteria for the pharmacokinetic evaluation of ZT-1 on experimental animals.

Alkaloids↗

PubMed2001

Validated gas chromatographic-mass spectrometric assay for determination of the antifreezes ethylene glycol and diethylene glycol in human plasma after microwave-assisted pivalylation.

A gas chromatographic-mass spectrometric assay is described for identification and quantification of the antifreezes ethylene glycol (EG) and diethylene glycol (DEG) in plasma for early diagnosis of a glycol intoxication. After addition of 1,3-propanediol as internal standard, the plasma sample was deproteinized by acetone and an aliquot of the supernatant was evaporated followed by microwave-assisted pivalylation. After gas chromatographic separation, the glycols were first identified by comparison of the full mass spectra with reference spectra and then quantified. The quantification has been validated according to the criteria established by the Journal of Chromatography B. The assay was found to be selective. The calibration curves for EG and DEG were linear from 0.1 g/l to 1.0 g/l. The limit of detection for EG and DEG was 0.01 g/l and the limit of quantification for both was 0.1 g/l. The absolute recoveries were 50 and 65% for the low quality control samples and 51 and 73% for the high quality control samples of EG and DEG, respectively. Intra- and inter-day accuracy and precision were inside the required limits. The glycols in frozen plasma samples were stable for more than 6 months. The method was successfully applied to several authentic plasma samples from patients intoxicated with glycols. It has also been suitable for analysis of EG and DEG in urine.

Ethylene Glycol↗

PubMed2005

Quantitative proteomic analysis using isobaric protein tags enables rapid comparison of changes in transcript and protein levels in transformed cells.

Isobaric tags for relative and absolute quantitation, an approach to concurrent, relative quantification of proteins present in four cell preparations, have recently been described. To validate this approach using complex mammalian cell samples that show subtle differences in protein levels, a model stem cell-like cell line (FDCP-mix) in the presence or absence of the leukemogenic oncogene TEL/PDGFRbeta has been studied. Cell lysates were proteolytically digested, and peptides within each sample were labeled with one of four isobaric, isotope-coded tags via their N-terminal and/or lysine side chains. The four labeled samples are mixed and peptides separated by two-dimensional liquid chromatography online to a mass spectrometer (LC-MS). Upon peptide fragmentation, each tag releases a distinct mass reporter ion; the ratio of the four reporters therefore gives relative abundances of the given peptide. Relative quantification of proteins is derived using summed data from a number of peptides. TEL/PDGFRbeta leukemic oncogene-mediated changes in protein levels were compared with those seen in microarray analysis of control and transfected FDCP-mix cells. Changes at the protein level in most cases reflected those seen at the transcriptome level. Nonetheless, novel differences in protein expression were found that indicate potential mechanisms for effects of this oncogene.

Amino Acid Sequence↗

PubMed2006

High-performance liquid chromatography method for urinary trans,trans-muconic acid. Application to environmental exposure to benzene.

This report describes a specific and precise high-performance liquid chromatography (HPLC) method for the quantification of trans,trans-muconic acid in human urine. The procedure involved a highly efficient Bond-Elut SAX extraction with 20% acetic acid elution. The HPLC analysis used a sodium acetate/methanol mobile phase with a C18 reverse phase column and UV detection at 265 nm. The recovery, precision, linearity, and limits of detection and quantification of the method were determined. Mean absolute recoveries were between 97% and 115%. The calibration curve showed a correlation coefficient of 0.9955 and the limit of detection was determined to be 10.8 microg/L. The method is suitable for evaluation of occupational and environmental benzene exposure in humans. The study of urinary trans,trans-muconic acid of two populations of children to evaluate environmental benzene exposure is presented.

Adult↗

PubMed2003

Gene expression analysis using single molecule detection.

Recent developments of single molecule detection techniques and in particular the introduction of fluorescence correlation spectroscopy (FCS) led to a number of important applications in biological research. We present a unique approach for the gene expression analysis using dual-color cross-correlation. The expression assay is based on gene-specific hybridization of two dye-labeled DNA probes to a selected target gene. The counting of the dual-labeled molecules within the solution allows the quantification of the expressed gene copies in absolute numbers. As detection and analysis by FCS can be performed at the level of single molecules, there is no need for any type of amplification. We describe the gene expression assay and present data demonstrating the capacity of this novel technology. In order to prove the gene specificity, we performed experiments with gene-depleted total cDNA. The biological application was demonstrated by quantifying selected high, medium and low abundant genes in cDNA prepared from HL-60 cells.

Actins↗

PubMed1994

Assessment of epidermal dendritic cell markers and T-lymphocytes in psoriasis.

Epidermal dendritic and T-cell counts have been performed in lesional and non-lesional skin from 35 psoriatic patients. The aims were to investigate absolute changes and interrelationships between these cellular elements in psoriasis and to explain apparent discrepancies between these results and reports in the literature. In non-lesional skin, the most frequently expressed dendritic cell marker was CD1a. HLA-DR+ and alpha-mannosidase+ dendritic cells were approximately 50 per cent and S100+ cells were 25 per cent as frequent. T-lymphocytes were rare, CD4+ cells predominating. In lesional psoriatic epidermis, there was a definite increase (approximately two-fold) in the absolute number of CD1a+ dendritic cells. This differs from the conclusions from the majority of previous studies. However, when cell counts were expressed per unit area of vertical section, there was a decrease in CD1a+ cells in lesional skin, which is an explanation for this discrepancy. There was a greater increase in absolute HLA-DR+ cell counts, so that the numbers of cells expressing CD1a and HLA-DR were similar in lesional skin. S100 expression increased proportionately with CD1a+, but there was no absolute increase in alpha-mannosidase+ cells, which might represent a separate sub-population of dendritic cells. The greatest cellular increase was in T-lymphocytes, particularly CD8+. In lesional skin, direct correlations have been demonstrated between epidermal thickness, HLA-DR+ dendritic cells and T-lymphocytes, particularly CD8+ cells. We would suggest that the present method of quantification is of value for the analysis of absolute changes in epidermal infiltrates, particularly psoriasis, and could be applied to other epidermal pathologies.

Adult↗

PubMed2005

A validated liquid chromatography-mass spectrometry method for the determination of leukotrienes B4 and B5 produced by stimulated human polymorphonuclear leukocytes.

A validated high-performance liquid chromatography (HPLC)-mass spectrometry method has been developed for the simultaneous assay of leukotrienes (LTs) B4 and B5, derived from omega-6 arachidonic acid and omega-3 polyunsaturated fatty acids (PUFA), respectively, produced by human polymorphonuclear leukocytes (PMNLs) stimulated with calcium ionophore A23187. The HPLC separation of PMNL ether extracts was performed on a reversed-phase column using a gradient elution program of 15 mM ammonium acetate and MeOH. Detection was performed by electrospray ionization-single quadripole mass spectrometry using single ion reaction monitoring in the negative mode at m/z 333.3 [M-H](-) and m/z 335.2 for prostaglandin B2/LTB5 and LTB4, respectively. The calibration curves for LTB4 and LTB5 were linear over the ranges 165-990 and 0.825-13.2 ng/ml, respectively. The lower limit of quantification for LTB5 was 0.66 ng/ml. The mean absolute recoveries for LTB4 and LTB5 were 81+/-4.8% and 82+/-5.9%, respectively. The method is precise with mean interday CVs for LTB4 and LTB5 within 7.1-10.7, and 3.8-9.4%, respectively, and accurate (range of interday deviations for LTB4 and LTB5 were -7.8 to 1, and -5 to 9% , respectively). The method has been validated and is being applied to the simultaneous quantification of the leukotrienes B4 and B5 in stimulated PMNLs in a clinical protocol studying the influence of a diet enriched in omega-3 PUFA on various surrogate markers of inflammation in young cystic fibrosis patients.

Calibration↗