Springer protocols feed by Imaging/Radiology 
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This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.Quantitation of Plasma Renin Activity in Plasma Using Liquid Chromatography & ndash;Tandem Mass Spectrometry (LC-MS/MS)
We describe a semi-automated and simple method for the accurate and precise measurement of PRA from 500 & mu;L of plasma (250 & mu;L if blank subtraction is omitted, as discussed) using a liquid chromatography and tandem mass spectrometry (LC-MS/MS) method for angiotensin I (AngI) in 96-well format. After a 3 h AngI generation step at 37 & deg;C in buffering conditions at pH 6, the reaction is quenched with 10 % formic acid containing AngI internal standard. Sample preparation then proceeds with offline solid phase extraction, two wash steps, and methanol elution followed by injection into the LC-MS/MS system. Quantitation...
Source: Springer protocols feed by Imaging/Radiology - January 7, 2016 Category: Radiology Source Type: news
Quantification of & gamma;-Aminobutyric Acid in Cerebrospinal Fluid Using Liquid Chromatography-Electrospray Tandem Mass Spectrometry
We describe a simple stable isotope dilution method for accurate and precise measurement of & gamma;-aminobutyric acid (GABA), a major inhibitory neurotransmitter in human cerebrospinal fluid (CSF) as a clinical diagnostic test. Determination of GABA in CSF (50 & mu;L) was performed utilizing high performance liquid chromatography coupled with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Analysis of free and total GABA requires two individual sample preparations and mass spectrometry analyses. Free GABA in CSF is determined by a 1:2 dilution with internal standard (GABA-D2) and injected direc...
Source: Springer protocols feed by Imaging/Radiology - January 7, 2016 Category: Radiology Source Type: news
Quantification of Dihydroxyacetone Phosphate (DHAP) in Human Red Blood Cells by HPLC-TripleTOF 56 & trade; Mass Spectrometer
Triosephosphate isomerase (TPI) is a glycolytic enzyme which catalyzes the interconversion between glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP). TPI deficiency results in accumulation of DHAP in human red blood cells and other tissues. The disease is characterized by congenital hemolytic anemia, and progressive neuromuscular dysfunction. The laboratory diagnosis is generally made by measurement of TPI activity in RBCs. Measurement of DHAP can be useful in further confirmation and follow-up of the disease. We developed HPLC/TOF-MS method for quantitation of DHAP in RBCs. The method involves simple ...
Source: Springer protocols feed by Imaging/Radiology - January 7, 2016 Category: Radiology Source Type: news
High-Throughput Serum 25-Hydroxy Vitamin D Testing with Automated Sample Preparation
Serum from bar-coded tubes, and then internal standard, are pipetted to 96-well plates with an 8-channel automated liquid handler (ALH). The first precipitation reagent (methanol:ZnSO4) is added and mixed with the 8-channel ALH. A second protein precipitating agent, 1 % formic acid in acetonitrile, is added and mixed with a 96-channel ALH. After a 4-min delay for larger precipitates to settle to the bottom of the plate, the upper 36 % of the precipitate/supernatant mix is transferred with the 96-channel ALH to a Sigma Hybrid SPE® plate and vacuumed through for removal of phospholipids and precipitated proteins. The fil...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Quantification of 1,25-Dihydroxyvitamin D2 and D3 in Serum Using Liquid Chromatography-Tandem Mass Spectrometry
We present here an effective and accurate method for measuring 1,25-dihydroxyvitamin D3 and 1,25-dihydroxyvitamin D2 by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) after immunoaffinity extraction. The MS/MS is operated in multiple reaction mode with positive electrospray. Quantification is based on peak area ratios of the analytes to respective deuterated internal standards. This method offered a linear range from 4.0 to 160.0 pg/mL with analytical recovery of 89.9–115.5 % for both 1,25-dihydroxyvitamin D3 and 1,25-dihydroxyvitamin D2. (Source: Springer protocols feed by Imaging/Radiology)
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Urinary Succinylacetone Analysis by Gas Chromatography-Mass Spectrometry (GC-MS)
Succinylacetone (SA) is used for the diagnosis and monitoring of patients with tyrosinemia type I (Tyr I). SA is exclusively elevated in blood and urine of patients with Tyr I. As urinary SA concentration is much higher than blood, SA is usually tested in urine samples. Urinary SA quantitation by gas chromatography mass spectrometry (GC-MS) is described in this chapter. The urine sample in the amount of 1 μmol creatinine is used for testing. 3,4,5,6,7-13C5-succinylacetone (13C5-SA) is used as an internal standard (IS). SA and 13C5-SA are oximated and extracted from urine with organic solvents, and then derivatized to fo...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Quantification of Free Carnitine and Acylcarnitines in Plasma or Serum Using HPLC/MS/MS
Acylcarnitines are formed by esterification between fatty acids CoA or organic acids CoA molecules and carnitine. In various fatty acids oxidation defects and organic acidurias, there is increased concentration of corresponding acylcarnitines. Abnormalities in specific acylcarnitines are used in the diagnosis of fatty acids oxidation defects and organic acidurias. Most commonly used method for the assay of acylcarnitines is HPLC-tandem mass spectrometry (HPLC/MS/MS). A HPLC/MS/MS method is described for the quantification of number of acylcarnitines. The method involves butylation of carnitine/acylcarnitines using acidifie...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Quantification of Dehydroepiandrosterone, 11-Deoxycortisol, 17-Hydroxyprogesterone, and Testosterone by Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS)
Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders due to enzymatic defects in the biosynthetic pathway of cortisol and/or aldosterone. The analysis of cortisol, 17-hydroxyprogesterone (OHPG), dehydroepiandrosterone (DHEA), 11-deoxycortisol, and testosterone is generally performed in the diagnosis and/or follow-up of CAH. Cortisol is generally analyzed by immunoassays whereas other hormones are preferably assayed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). A multiple reaction monitoring, positive mode atmospheric pressure chemical ionization, LC/MS/MS method is described for ...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
A Simple, High-Throughput Method for Analysis of Ceramide, Glucosylceramide, and Ceramide Trihexoside in Dried Blood Spots by LC/MS/MS
A unique monophasic extraction system coupled with LC/MS/MS to reduce matrix effects for sphingolipid analysis was developed. A solvent mixture of methanol, acetonitrile, and water was identified to simultaneously extract multiple sphingolipids with broad polarity range. To reduce matrix effects, the targeted sphingolipids were analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The extraction solvent was used as an isocratic mobile phase in chromatographic separation to eliminate solvent exchange steps and enable high-throughput multiple lipid assay. The assay is linear for ceramide from 0.6 to 9 μg/...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Quantitation of S-Adenosylmethionine and S-Adenosylhomocysteine in Plasma Using Liquid Chromatography-Electrospray Tandem Mass Spectrometry
We describe a simple stable isotope dilution method for accurate determination of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in plasma as a diagnostic test. SAM and SAH are key metabolic intermediates of methionine metabolism and the methylation cycle. Determination of SAM and SAH in plasma was performed by high performance liquid chromatography coupled with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Calibrators (SAM and SAH) and internal standards (2H3-SAM and 2H4-SAH) were included in each analytical run for calibration. Sample preparation involved combining 20 μL samp...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Quantitation of Plasma Renin Activity in Plasma Using Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS)
We describe a semi-automated and simple method for the accurate and precise measurement of PRA from 500 μL of plasma (250 μL if blank subtraction is omitted, as discussed) using a liquid chromatography and tandem mass spectrometry (LC-MS/MS) method for angiotensin I (AngI) in 96-well format. After a 3 h AngI generation step at 37 °C in buffering conditions at pH 6, the reaction is quenched with 10 % formic acid containing AngI internal standard. Sample preparation then proceeds with offline solid phase extraction, two wash steps, and methanol elution followed by injection into the LC-MS/MS system. Quantitation is...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Urine Pyrimidine Metabolite Determination by HPLC Tandem Mass Spectrometry
Pyrimidine diseases result from deficiencies in pyrimidine de novo synthesis, degradation, and salvage pathways. Enzymatic deficiencies in pyrimidine catabolism lead to mitochondrial neurogastrointestinal encephalopathy (MNGIE), pyrimidinuria, dihydropyrimidinuria, ureidopropionic aciduria, and other disorders. While MNGIE presents with gastrointestinal dysmotility, cachexia, and leukoencephalopathy, pyrimidinuria and dihydropyrimidinuria may show symptoms of epilepsy, autism, mental retardation, and dysmorphic features. The application of HPLC-MS/MS facilitates rapid screening of pyrimidine metabolites. Here we describe a...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Urine Purine Metabolite Determination by UPLC-Tandem Mass Spectrometry
Inborn errors of purine metabolism, either deficiencies of synthesis or catabolism pathways, lead to a wide spectrum of clinical presentations: urolithiasis (adenine phosphoribosyltransferase), primary immune deficiency (adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency), severe intellectual disability, and other neurological symptoms (Lesch-Nyhan disease, adenylosuccinase deficiency, and molybdenum cofactor deficiency). A rapid quantitative purine assay was developed using UPLC-MS/MS to determine purine nucleoside and base concentrations in urine. Taking advantages of ultra performance liquid c...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Determination of Phenylalanine and Tyrosine by High Performance Liquid Chromatography-Tandem Mass Spectrometry
Hyperphenylalaninemia/phenylketonuria (PKU) is one of the most common inborn errors of amino acid metabolism affecting about 1:15,000 infants in the United States. PKU is an autosomal recessive disorder that if untreated results in mental retardation. The most common cause of PKU is deficiency of the enzyme phenylalanine hydroxylase that converts phenylalanine to tyrosine. Tyrosine deficiency results in impaired synthesis of catecholamines and thyroxine. Less commonly, it can result from defects in the synthesis or regeneration of tetrahydrobiopterin (BH4), an essential cofactor for the enzyme phenylalanine hydroxylase. In...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
Quantitation of Parathyroid Hormone in Serum or Plasma by Liquid Chromatography-Tandem Mass Spectrometry
Parathyroid hormone (PTH), an 84 amino acid peptide hormone, is an important regulator of calcium homeostasis. Quantitation of PTH in serum is useful for the diagnosis of primary hyperparathyroidism, hypoparathyroidism, and for monitoring osteodystrophy in patients with renal failure. The biological activity of PTH arises from binding of PTH (N terminus) to its target receptor (D’Amour et al., Kidney Int 68: 998–1007, 2005). Several C-terminal and N-terminal fragments circulate in normal subjects. Recent studies have demonstrated that accurate quantitation of PTH fragments may be of clinical value. In this chap...
Source: Springer protocols feed by Imaging/Radiology - November 27, 2015 Category: Radiology Source Type: news
