Carnitine determination by an enzymatic cycling method with carnitine dehydrogenase

1994 ◽  
Vol 40 (5) ◽  
pp. 817-821 ◽  
Author(s):  
M Takahashi ◽  
S Ueda ◽  
H Misaki ◽  
N Sugiyama ◽  
K Matsumoto ◽  
...  
Keyword(s):  
Calibration Curve ◽  
Specific Method ◽  
Enzymatic Cycling ◽  
Analytical Recovery ◽  
Highly Sensitive

Abstract We describe a highly sensitive and specific method for determining L-carnitine in serum by use of carnitine dehydrogenase (EC 1.1.1.108). The method involves a new enzymatic cycling technique with NADH, thio-NAD+, and carnitine dehydrogenase, and measures the increase of absorbance at 415 nm of thio-NADH produced at 37 degrees C during the reaction: [formula: see text] The calibration curve for L-carnitine in serum was linear between 5 and 250 mumol/L. Analytical recovery was 96.5-106%, and within-run and between-run imprecisions (CV) were 0.66-4.33% and 1.02-2.56%, respectively. This method was free from interference by bilirubin, hemoglobin, various acyl-DL-carnitines, and ascorbate. The procedure is simple, rapid, accurate, and automatable. The amount of free L-carnitine in serum (53.6 +/- 11.7 mumol/L, n = 200) was greater in men than in women (45.1 +/- 14.2 mumol/L, n = 200) (mean +/- SD).

Measurement of glycated protein by a rapid and specific method for absolute quantification of lysine-bound glucose.

1987 ◽  
Vol 33 (9) ◽  
pp. 1656-1659 ◽  
Author(s):  
H Drexel ◽  
H Klocker ◽  
J R Patsch ◽  
C Breier ◽  
H Braunsteiner
Keyword(s):  
Serum Proteins ◽  
Stationary Phases ◽  
Protein A ◽  
Absolute Quantification ◽  
Specific Method ◽  
Glycated Protein ◽  
Analytical Recovery ◽  
Highly Sensitive ◽  
Main Column ◽  
Liquid Chromatographic

Abstract We modified the liquid-chromatographic assay of Schleicher and Wieland (J Clin Chem Clin Biochem 1981; 19:81-7) for measuring lysine-bound glucose in serum proteins, increasing its performance and practicality. After precipitating serum proteins from 10- to 50-microL samples with ethanol (700 mL/L) and hydrolyzing these in 6 mol/L HCl, we inject 20 microL of the diluted hydrolysate directly into the chromatograph, which consists of an acid-resistant C18 precolumn combined with a high-resolution C18 main column. The eluent is 3.5 mmol/L H3PO4 solution containing 30 mL of acetonitrile per liter. These modifications increase sensitivity, provide excellent resolution and longevity of stationary phases, shorten assay times to 15 to 20 min, and are suited for automation. The assay is highly sensitive and highly specific, quantifying nanomoles of lysine-bound glucose per milligram of protein. A precision (CV) of 5.1% is achievable at physiological and supra-physiological glucose concentrations, and analytical recovery is 99%. This inexpensive method has been applied to serum albumin, bulk serum proteins, and preparations of low-density lipoproteins and immunoglobulins.

scholarly journals Highly sensitive and rapid gas biosensor for formaldehyde based on an enzymatic cycling system

2015 ◽  
Vol 210 ◽  
pp. 241-247 ◽  
Author(s):  
Akira Monkawa ◽  
Tomoko Gessei ◽  
Yuki Takimoto ◽  
Nobuaki Jo ◽  
Toshiaki Wada ◽  
...  
Keyword(s):  
Enzymatic Cycling ◽  
Highly Sensitive ◽  
Cycling System

scholarly journals Spectrofluorimetric Determination of Vigabatrin and Gabapentin in Dosage Forms and Spiked Plasma Samples Through Derivatization with 4-Chloro-7-Nitrobenzo-2-Oxa-1,3-Diazole

2001 ◽  
Vol 84 (4) ◽  
pp. 1017-1024 ◽  
Author(s):  
Ekram M Hassan ◽  
Fathalla Belal ◽  
Omar A Al-Deeb ◽  
Nasr Y Khalil
Keyword(s):  
Reaction Pathway ◽  
Dosage Forms ◽  
Specific Method ◽  
Plasma Samples ◽  
Spiked Plasma ◽  
Highly Sensitive ◽  
Percent Recovery ◽  
Spectrofluorimetric Determination ◽  
Label Claim

Abstract A highly sensitive and specific method is proposed for the determination of vigabatrin (I) and gabapentin (II) in their dosage forms and spiked human plasma. The method is based on coupling the drugs with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in borate buffer at pH 7.1 and measuring the resulting fluorescence at 532 nm after excitation at 465 nm. The fluorescence intensity was a linear function of the concentration of the drugs over the ranges of 1.3–6.5 and 1.7–8.5 μg/mL for I and II, respectively. Minimum detectability values were 0.54 μg/mL (4.2 × 10−6M) and 0.97 μg/mL (5.7 × 10−6M) for I and II, respectively, under the described conditions. The proposed method was successfully applied to the determination of the 2 drugs in their dosage forms, and the percent recoveries ± standard deviation (SD) were 104.53 ± 1.2 and 100.00 ± 1.32 of the label claim for I and II, respectively. The method was further applied to the determination of vigabatrin in spiked plasma samples. The percent recovery ± SD was 101.58 ± 2.68. Interference from endogenous α-amino acids was overcome through selective complexation with freshly prepared Cu(OH)2. The interference likely to be encountered from co-administered drugs, such as carbamazepine, cimetidine, clonazepam, clopazam, phenobarbital, valproic acid, and lamotrigine, was also studied. A reaction pathway is suggested.

scholarly journals Highly Sensitive Cholesterol Assay with Enzymatic Cycling Applied to Measurement of Remnant Lipoprotein-Cholesterol in Serum

2002 ◽  
Vol 48 (5) ◽  
pp. 737-741 ◽  
Author(s):  
Koji Kishi ◽  
Koji Ochiai ◽  
Yohsuke Ohta ◽  
Yahiro Uemura ◽  
Kazushi Kanatani ◽  
...  
Keyword(s):  
Cholesterol Oxidase ◽  
Lipoprotein Cholesterol ◽  
Cholesterol Concentration ◽  
Separation Procedure ◽  
Enzymatic Method ◽  
Healthy Individuals ◽  
Apo B ◽  
Remnant Lipoprotein ◽  
Enzymatic Cycling ◽  
Highly Sensitive

Abstract Background: Remnant lipoprotein-cholesterol (RLP-C) concentrations in sera of healthy individuals are very low (0.080–0.437 mmol/L), making conventional cholesterol methods poorly suited to this purpose. We have developed a highly sensitive cholesterol assay (CD method) and applied it to the RLP-C assay. Methods: The CD shuttled cholesterol reversibly between reduced and oxidized forms in the presence of thio-NAD and NADH. The production rate of thio-NADH correlated with the cholesterol concentration and was measured by the absorbance at 404/500 nm. This CD method was combined with an immunoaffinity separation procedure with specific monoclonal antibodies to apolipoprotein (apo) A1 and apo B-100 and used for RLP-C assay. Results were compared with a RLP-C method that uses cholesterol oxidase, peroxidase, and chromogenic substrate. Results: The CD method could detect 0.10 × 10−3 mmol/L cholesterol and was at least 5 times more sensitive than the conventional enzymatic method. Within- and between-day imprecision (as CVs) of the RLP-C assay with the CD method was <4%. Regression analysis of RLP-C assays with the new (y) and conventional (x) cholesterol methods yielded: y = 1.02x − 0.008 mmol/L (Sy|x = 0.0065 mmol/L; r = 0.997; n = 297). Conclusions: Serum RLP-C can be measured by the CD method. The CD method may be useful for other assays that require sensitive cholesterol measurements in biological materials.

Determination of beta 2-microglobulin in human urine and serum by latex immunoassay.

1981 ◽  
Vol 27 (6) ◽  
pp. 832-837 ◽  
Author(s):  
A M Bernard ◽  
A Vyskocil ◽  
R R Lauwerys
Keyword(s):  
Human Urine ◽  
Albumin Solution ◽  
Coated Particles ◽  
Analytical Recovery ◽  
Highly Sensitive ◽  
Human Urine And Serum ◽  
Beta 2 ◽  
Beta 2 Microglobulin ◽  
Urine And Serum

Abstract This highly sensitive method for determination of beta 2-microglobulin (beta 2-m) in human urine or serum is based on direct agglutination by beta 2-m of latex particles on which an antibody against beta 2-m is adsorbed. The agglutination is quantified by counting the remaining unagglutinated particles, or by turbidimetry. A novel aspect of this method is the capability to prevent nonspecific agglutination of the antibody-coated particles by diluting them with an albumin solution of well-defined characteristics (pH, freshness, concentration) just before the assay. The assayable concentration range is 1--32 micrograms/L, the detection limit 0.5 micrograms/L. Within-assay CV, based on 10 determinations of beta 2-m in urine and serum at two different dilutions, ranged from 4.6 to 8.7%. Between-assay CV, calculated from 10 determinations of beta 2-m in urine and serum, was 10 and 8.4%, respectively. Analytical recovery of beta 2-m in urine averaged 97% and in serum 104% (n = 10). No component of urine or serum interfered. Coefficients of correlation for beta 2-m in urine or serum as measured by radioimmunoassay and latex immunoassay were 0.97 and 0.93, respectively. Concentrations of beta 2-m in serum and urine from 33 healthy men (ages 20 to 67 years) averaged 1.5 mg/l and 54 micrograms/g of creatine, respectively.

Colorimetry of hemoglobin in plasma with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS).

1984 ◽  
Vol 30 (3) ◽  
pp. 357-359 ◽  
Author(s):  
M Takayanagi ◽  
T Yashiro
Keyword(s):  
Hydrogen Peroxide ◽  
Calibration Curve ◽  
Plasma Proteins ◽  
Sulfonic Acid ◽  
Minimum Detectable Concentration ◽  
Colored Form ◽  
Analytical Recovery ◽  
Detectable Concentration ◽  
Precision And Accuracy

Abstract Hemoglobin in plasma can be determined by the color-developing action of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid), which is oxidized to a colored form by a peroxidase-like effect of hemoglobin in the presence of hydrogen peroxide. Sensitivity, precision, and accuracy are discussed. The calibration curve is linear for hemoglobin concentrations up to 1 g/L; the minimum detectable concentration is 20 mg/L. The within-run precision (CV) was 2.39%, analytical recovery 101.8%. Interference from plasma proteins and lipids was eliminated by centrifuging the reaction mixture before measuring its absorbance at 410 nm.

scholarly journals The efficiency of sodC gene / N. meningitidis detection in comparison with the classical methods for the diagnosis of meningococcal infection / Evaluarea eficienţei Real Time PCR TaqMan utilizând gena sodC / N. meningitidis în comparaţie cu metodele clasice utilizate în diagnosticul infecţiei meningococice

2015 ◽  
Vol 23 (1) ◽  
Author(s):  
Roxana Elena Nemescu ◽  
Ramona Gabriela Ursu ◽  
Carmen Mihaela Dorobăț ◽  
Luminița Smaranda Iancu
Keyword(s):  
Antibiotic Therapy ◽  
Real Time ◽  
Real Time Pcr ◽  
Latex Agglutination ◽  
Blood Analysis ◽  
Meningococcal Infection ◽  
Specific Method ◽  
Rt Pcr ◽  
Highly Sensitive ◽  
Etiological Agents

AbstractMeningococcal infection requires a fast and accurate diagnostic method in order to correctly initiate the antibiotic therapy. The aim of our study was to assess the efficiency of Real Time PCR -Taq Man using sod C gene / N. meningitidis in comparison with the classical methods for the diagnosis of meningococcal infection - direct microscopy, cultivation, latex agglutination and blood culture. We have detected 24/44 (54.54%) patients with meningococcal infection. In both cases of patients with / without previous antibiotic therapy before admission, the AUC (area under curve) had the highest values for RT PCR in CSF and blood analysis. This sod C RT-PCR assay is a highly sensitive and specific method for detection of Neisseria meningitis and it would be useful to include this method like a multiplex in routine testing of patients with clinical meningococcal infection for other etiological agents also.

scholarly journals COMPLEX ULTRASOUND CHARACTERISTICS OF THE PANCREAS IN CHILDREN WITH CYSTIC FIBROSIS

2018 ◽  
Vol 63 (5) ◽  
pp. 155-161
Author(s):  
V. P. Bulatov ◽  
N. V. Rylova
Keyword(s):  
Cystic Fibrosis ◽  
Pulse Wave ◽  
Splenic Vein ◽  
Structural Condition ◽  
Specific Method ◽  
Healthy Children ◽  
Non Invasive ◽  
Pancreatic Damage ◽  
Highly Sensitive ◽  
Vein Diameter

Objective:to evaluate the condition of the pancreas in children with cystic fibrosis using complex ultrasound.We examined 80 children from 3 to 18 years: 50 children with mixed cystic fibrosis and 30 conditionally healthy children. The complex ultrasound consisted of gray scale US, color dopplerography, energy dopplerography and pulse-wave dopplerography.Results.A complex study of such parameters as splenic vein diameter, volume and linear blood flow with postprandial response help to obtain more complete picture of pancreatic damage in children with cystic fibrosis. This highly sensitive and specific method with nutritional load has no contraindications, it is non-invasive, readily available, and it does not require large costs and opens up wide prospects in diagnosing the structural condition of the pancreas in children with cystic fibrosis.

Highly sensitive enzyme immunoassay of proinsulin immunoreactivity with use of two monoclonal antibodies

1993 ◽  
Vol 39 (10) ◽  
pp. 2146-2150 ◽  
Author(s):  
L L Kjems ◽  
M E Røder ◽  
B Dinesen ◽  
S G Hartling ◽  
P N Jørgensen ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Detection Limit ◽  
Human Serum ◽  
Enzyme Immunoassay ◽  
Healthy Subjects ◽  
Sandwich Elisa ◽  
C Peptide ◽  
Peptide Antibody ◽  
Analytical Recovery ◽  
Highly Sensitive

Abstract A highly sensitive two-site sandwich ELISA measuring total proinsulin immunoreactive material in serum or plasma was developed. The assay was based on two monoclonal antibodies, an anti-C-peptide antibody bound to a microtest plate and a biotin-labeled anti-insulin antibody. The detection limit (3 SD above zero value) in buffer was 0.05 pmol/L, corresponding to 0.25 pmol/L in human serum (diluted 1:5). The linear calibrator range was 0.05-20 pmol/L. Interassay CVs were 4.7% at a median (range) of 2.3 pmol/L (1.4-2.8 pmol/L, n = 8), 6.7% at 5.1 pmol/L (3.3-8.0 pmol/L, n = 8), and 8.7% at 10.0 pmol/L (8-12 pmol/L, n = 10). Mean analytical recovery of added human proinsulin (hPI) (2, 5, and 10 pmol/L) to serum was 84% (range 68-128%, n = 9). Human insulin and human C-peptide did not cross-react at 5000 and 10,000 pmol/L, respectively. The four major proinsulin conversion intermediates reacted 65-99%: split(32-33)hPI 74%, des-(31,32)hPI 65%, split(65-66)hPI 78%, and des(64,65)hPI 99%. All serum values from 38 fasting healthy subjects were above the detection limit: median (range) 4.0 (2.1-12.6) pmol/L.

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