Measuring Urinary Glycosaminoglycans in the Presence of Protein: An Improved Screening Procedure for Mucopolysaccharidoses Based on Dimethylmethylene Blue

1992 ◽  
Vol 38 (6) ◽  
pp. 803-807 ◽  
Author(s):  
J G de Jong ◽  
R A Wevers ◽  
R Liebrand-van Sambeek
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
False Negative ◽  
Urine Samples ◽  
Screening Procedure ◽  
Urinary Proteins ◽  
Negative Results ◽  
False Negative Results ◽  
Metabolic Screening ◽  
Urinary Glycosaminoglycans

Abstract Earlier we described a simple and reliable screening procedure in urine for mucopolysaccharidoses based on the color reaction of glycosaminoglycans (GAGs) with dimethylmethylene blue. At physiological concentrations of urinary protein, we observed an obvious interference by protein in the assay. By modifying the assay, we abolished the protein interference. The modified procedure is not disturbed by human serum albumin, IgG (both tested with as much as 5 g/L of protein), or urinary proteins. The modified procedure appeared as reliable as the original. No false-negative results were found in a series of 26 urine samples from patients with mucopolysaccharidoses (sensitivity 100%). In a series of 405 urine samples offered for metabolic screening, 24 samples with increased GAG content and normal GAG composition were seen (specificity 94%). The method may also be applicable for determining GAG in other body fluids or solutions containing protein.

The spot test is not a reliable screening procedure for mucopolysaccharidoses

1991 ◽  
Vol 37 (4) ◽  
pp. 572-575 ◽  
Author(s):  
J G N de Jong ◽  
J J F Hasselman ◽  
A A J van Landeghem ◽  
H L Vader ◽  
R A Wevers
Keyword(s):  
False Positive ◽  
False Negative ◽  
Spot Test ◽  
Urine Samples ◽  
Screening Procedure ◽  
Negative Results ◽  
False Negative Results ◽  
Spot Tests ◽  
Metabolic Screening ◽  
Positive Results

Abstract To check the reliability of the Ames MPS paper spot test, which is based on the Azure A dye, we sent a series of urine samples to three laboratories where the spot test is part of the metabolic screening for mucopolysaccharidoses. In these laboratories false-negative results ranged between 19% and 35% and false-positive results ranged between 12% and 29% of all samples submitted. In contrast, the quantitative dimethylmethylene blue test (Clin Chem 1989;35:1472-7) detected an increased glycosaminoglycan content in all urine samples from mucopolysaccharidosis patients and gave no false-positive results. In the latter procedure, glycosaminoglycan content is expressed per millimole of creatinine, and age-dependent reference values are used. We conclude that the Ames spot test and other spot tests are unreliable as a screening procedure for mucopolysaccharidoses and should not be used to screen for these diseases.

scholarly journals Blood-borne, albumin-bound prostaglandin E2 may be involved in fever

1999 ◽  
Vol 276 (6) ◽  
pp. R1840-R1844 ◽  
Author(s):  
Andrej A. Romanovsky ◽  
Andrei I. Ivanov ◽  
Elena K. Karman
Keyword(s):  
Human Serum Albumin ◽  
Rectal Temperature ◽  
Enzymatic Degradation ◽  
False Negative ◽  
Free Ligand ◽  
Free Form ◽  
Carrier Protein ◽  
Negative Results ◽  
False Negative Results ◽  
Pyrogenic Activity

Although the involvement of blood-borne PGE2 in fever has been hypothesized by several authors and has substantial experimental support, the current literature often rejects this hypothesis because several attempts to induce fever by a peripheral PGE2 failed. However, it is usually ignored that the amphipathic molecules of PGE2 are readily self-associating and that such an aggregation could have prevented the peripherally administered PGE2 (free form) from expressing its pyrogenic activity, thus leading to false negative results. To ensure disaggregation of PGE2, we prepared its complex within a carrier protein, human serum albumin (HSA). HSA was purified with activated charcoal and polymixin B-polyacrylamide gel and incubated with PGE2 for 1 h at 37°C. Adult Chinchilla rabbits were injected intravenously with PGE2-HSA complex in either the higher (75 μg/kg PGE2:30 mg/kg HSA) or the lower (15 μg/kg:6 mg/kg) dose, and the rectal temperature (Tr) was measured. In the controls, either the ligand alone or the carrier alone was administered. At the higher dose, neither free PGE2 nor albumin alone was pyrogenic, whereas the PGE2-HSA complex produced a fever characterized by a short latency (<10 min) and a maximal Tr rise of 0.7 ± 0.2°C. At the lower dose, none of the substances affected the Tr. This study demonstrates a marked pyrogenic activity of the intravenous PGE2-HSA, but not of the free PGE2. Administration of a preformed complex may be more physiologically relevant than administration of the free ligand because of the ligand’s disaggregation, protection from enzymatic degradation, and facilitated delivery to targets. Our study supports the hypothesis that peripheral PGE2 is involved in fever genesis.

False-negative results in the immunoassay analysis of drugs of abuse: can adulterants be detected by sample check test?

2017 ◽  
Vol 55 (3) ◽  
pp. 348-354 ◽  
Author(s):  
Barbara Matriciani ◽  
Bernd Huppertz ◽  
Ruprecht Keller ◽  
Ralf Weiskirchen
Keyword(s):  
Drugs Of Abuse ◽  
Methadone Treatment ◽  
False Negative ◽  
Urine Samples ◽  
Morphine Sulphate ◽  
Negative Results ◽  
Health Authorities ◽  
False Negative Results ◽  
Three Samples ◽  
Immunological Assays

Background The dilution or adulteration of urine is a serious problem in drugs of abuse testing. Tests to identify adulteration are currently available. This study investigated the ability of the CEDIA® sample check to detect adulteration. Methods Eight different drugs of abuse were added to a urine sample obtained from a healthy, drug-free subject: 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), 3,4-methylenedioxyamphetamine, benzoylecgonine, D-amphetamine sulphate, ethyl-D-glucuronide, morphine sulphate, oxazepam, (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Urine samples were diluted to yield three samples of drugs of abuse concentrations close to general cut-offs as used in methadone treatment centres, by health authorities for psychological tests and in traffic medicine. Aspirin, citric acid, CrO3, H2O2, soap, sodium metaborate, vitamin C were added in three, HCl and NaOH in one, and NaN3 in two concentrations. All samples were measured with commercially available immunological assays shortly after sample preparation and 24 h later. All samples were further analysed with the CEDIA® sample check reaction which may identify adulteration. Results Oxidizing reagents (H2O2 or CrO3) are most effective in interfering in the measurement of benzoylecgonine, EDDP, ethyl-D-glucuronide and morphine sulphate. The measurement of (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol is affected by many adulterants. Adulteration with HCl and NaOH was identified with the sample check reaction. NaN3 generated false negative results for a number of drugs of abuse. Conclusions Urine samples with drugs of abuse concentrations above cut-offs can be successfully tampered with adulterants in a way which cannot be detected with the CEDIA® sample check assay.

scholarly journals A Validated and Applicable Direct Injection LC/MS/MS Method of Fourteen Drugs of Abuse in Urine Samples to Avoid the False Positive/Negative Results of Immunoassay Techniques in Forensic Cases

2020 ◽  
Author(s):  
Tarek Mahdy ◽  
Abdulaziz Al-Sulaiti ◽  
Yasser Abdelqader ◽  
Abdelrahman Fikry ◽  
Gaffar Hag ◽  
...  
Keyword(s):  
False Positive ◽  
Drugs Of Abuse ◽  
Direct Injection ◽  
False Negative ◽  
Urine Samples ◽  
Injection Method ◽  
Negative Results ◽  
Immunoassay Technique ◽  
False Negative Results ◽  
Good Comparison

Many false positive and false negative results have been detected in immunoassay analyses of drugs of abuse in urine samples. A method of direct injection of diluted urine into LC/MS/MS was developed and validated for detection and quantitation of Amphetamine, Methamphetamine, MDMA, MDA, Benzoylecgonine, Ecgonine, Norpseudoephedrine, Ephedrine, Tapentadol, Tramadol, O-desmethyltramadol, Tapentadol, Pregabline, Gabapentine and Methadone to avoid the false positive and false negative results in urine samples. Linearity of Amphetamine, Methamphetamine MDMA, MDA, Benzoylecgonine, Ecgonine, Norpseudoephedrine and Ephedrine was (60-2400ng/mL), for Tapentadol, Tramadol, O-desmethyltramadol, and Methadone was (50-1600 ng/mL), and for Pregabline and Gabapentine was (100-4000ng/mL) and r2 ˃ 0.992 for all analysts. A 440 urine samples have been analyzed using both immunoassay technique and LC/MS/MS by direct injection method giving a good comparison to illustrate how this method was specific, accurate, precise, and applicable for forensic urine samples

Importance of creatinine analyses of urine when screening for abused drugs

1991 ◽  
Vol 37 (11) ◽  
pp. 1927-1931 ◽  
Author(s):  
P Lafolie ◽  
O Beck ◽  
G Blennow ◽  
L Boréus ◽  
S Borg ◽  
...  
Keyword(s):  
Drug Testing ◽  
Drugs Of Abuse ◽  
False Negative ◽  
Urine Samples ◽  
Heavy Smoker ◽  
Simple Method ◽  
Negative Results ◽  
False Negative Results ◽  
Abused Drugs ◽  
Urine Testing

Abstract We report here a simple method involving urine creatine measurements for testing authenticity and reducing false-negative results in urine testing for drugs of abuse. Urinary creatinine in consecutive patient samples (n = 176) ranged between 0.1 and 31.9 mmol/L (mean 9.8 +/- SD 6.2) and the osmolality in these urines ranged between 49 and 1183 mOsm/kg (mean 595 +/- SD 276). With other consecutive samples in which creatinine was (arbitrarily chosen) less than 4.3 mmol/L (n = 85), the correlation with osmolality was lower. In 10 randomly selected urine samples from different patients, all "clean" for all drugs of abuse in initial immunological drug testing with approved methodology (in which creatinine was less than 4.3 mmol/L and osmolality was less than 200 mOsm/kg), five patients turned out to be drug positive after a simple concentration by volume. In a formerly heavy smoker of cannabis, the excretion of cannabinoids and creatinine was monitored for 93 days. The substances showed very good correlation throughout this period (r = 0.93, P less than 0.001), whereas simple measurements of cannabinoid concentrations would have falsely indicated several relapses of cannabis abuse. Urine samples used in drug-abuse testing should be tested for creatinine; if creatinine is less than 4.0 mmol/L, negative results for drugs may not be valid.

Dimethylmethylene blue-based spectrophotometry of glycosaminoglycans in untreated urine: a rapid screening procedure for mucopolysaccharidoses.

1989 ◽  
Vol 35 (7) ◽  
pp. 1472-1477 ◽  
Author(s):  
J G de Jong ◽  
R A Wevers ◽  
C Laarakkers ◽  
B J Poorthuis
Keyword(s):  
Uronic Acid ◽  
Cetylpyridinium Chloride ◽  
False Negative ◽  
Rapid Screening ◽  
Screening Procedure ◽  
Negative Results ◽  
Morquio A ◽  
False Negative Results ◽  
Turbidity Test ◽  
Spot Tests

Abstract Glycosaminoglycans (GAGs) are measured in urine to screen for mucopolysaccharidoses. Other assay procedures are only qualitative (spot tests), can give false-negative results (spot tests, turbidity tests), or are relatively laborious (uronic acid-carbazole test). The present spectrophotometric procedure, based on the color reaction with dimethylmethylene blue (DMB), can be performed directly on untimed urine samples without prior precipitation. Reference values were age dependent. We tested urines of 27 patients with various mucopolysaccharidoses and compared results by three other procedures (cetylpyridinium chloride turbidity tests at pH 4.8 and at pH 7.0, and the uronic acid-carbazole test). In the DMB assay, GAGs were increased in 26 of the 27 patients. The exception was a Morquio A patient, whose activity of the defective enzyme was higher than in classical Morquio patients. Uronic acid, measured in precipitated GAG by the carbazole test, was increased in 23 of the 25 patients so tested. In the turbidity test at pH 7.0, values were increased in 24 of the 27 patients. In contrast, with the citrate-buffered (pH 4.8) turbidity measurement, GAG content was increased in only 19 of the 27 patients. This rapid and easy DMB method is a reliable screening procedure for mucopolysaccharidoses and compares well with procedures used hitherto.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

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