Effects of low and high relative molecular protein mass on four methods for total protein determination in urine

Lim, Chew W.; Chisnall, Wayne N.; Stokes, Yvonne M.; Debnam, Phillip; Crooke, Michael

doi:10.3109/00313029009063786

Cited by 11 publications

(10 citation statements)

References 18 publications

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“…Detection of aminoaciduria was carried out by a chromatographic method [18]. Urinary protein was assayed by a modified Bradford method (Bio-Rad Laboratories Ltd., Richmond, Calif., USA) [19]. In addition, the urine was electrophoresed in 8–15% polyacrylamide gel and stained with the silver method [20].…”

Section: Methodsmentioning

confidence: 99%

Renal Function in Adult Beta-Thalassemia/Hb E Disease

Ong-Ajyooth¹,

Malasit²,

Ong-Ajyooth³

et al. 1998

Nephron

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β-Thalassemia hemoglobin E (β-thal/Hb E) is the commonest form of hemoglobinopathy in Thailand. Shortened red cell life span, rapid iron turnover and tissue deposition of excess iron are major factors responsible for functional and physiological abnormalities found in various forms of thalassemia. Increased deposition of iron had been found in renal parenchyma of thalassemic patients, but no systematic study of the effect of the deposits on renal functions has been available. The purpose of this study is to describe the functional abnormalities of the kidney in patients with β-thal/Hb E and provide evidence that increased oxidative stress might be one of the factors responsible for the damage. Urine and serum samples from 95 patients with β-thal/Hb E were studied comparing with 27 age-matched healthy controls. No difference in the creatinine clearance was observed. β-thal/Hb E patients excreted significantly more urinary protein (0.8 ± 0.5 vs. 0.3±0.1 g/day, p < 0.001). Aminoaciduria was found in 16% of the patients. Analysis of urinary protein by SDS-PAGE electrophoresis and silver staining revealed abnormal pattern of protein with increased small molecular weight (<45 kD) bands. Morning urine analysis showed significant lower urine osmolality (578.3 ± 164.6 vs. 762.4 ± 169.9 mosm/kg, p < 0.001) in patients. Patients excreted more NAG (N-acetyl beta-D-glucosaminidase, 26.3 ± 41.3 vs. 8.4 ± 3.9 U/g Cr, p < 0.0001) and β₂-microglobulin, 124.3 ± 167 vs. 71 ± 65.5 µg/g Cr, p = 0.001. Plasma and urine MDA (malonyldialdehyde) levels were both raised (p < 0.0001). Nine patients were selected for renal acidification study. All were found to be normal, but showed poor response to DDAVP challenge (urine osmolality 533 ± 71). This is the first report of renal tubular defects found associated with β-thal/Hb E disease. The mechanism leading to the damage is not known but it might be related to increased oxidative stress secondary to tissue deposition of iron, as indicated by the raised levels of serum and urine MDA. It is not known whether these functional defects would have any long-term effects on the patients. Further studies are warranted and means of prevention of these defects should urgently be sought.

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Section: Methodsmentioning

confidence: 99%

Renal Function in Adult Beta-Thalassemia/Hb E Disease

Ong-Ajyooth¹,

Malasit²,

Ong-Ajyooth³

et al. 1998

Nephron

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“…Isolated CBAVD patients carry either a CF mutation (⌬F508 in 16 -83% of cases and R117H in 6 -29% of cases) and/or a 5T variant in intron 8 (12-47% of patients), supporting the hypothesis that CBAVD represents a mild, primary genital form of CF (2)(3)(4)(5)(6)(7). Three length variations of a polythymidine (polyT) tract within the splice acceptor site in intron 8 of the CFTR gene (GenBank accession no.…”

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confidence: 72%

“…Urinary total protein is frequently undetectable in predominantly tubular kidney disease, and common chemical methods also often fail to detect urinary total protein in predominantly tubular kidney disease, in which albumin usually represents Ͻ30% of the total protein content (2)(3)(4)(5)(6)(7)(8). However, some renal tubular disorders or interstitial nephritis (e.g., when caused by antibiotics and other tubulo-toxic substances) are easily treatable.…”

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confidence: 99%

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Patterns of Proteinuria: Urinary Sodium Dodecyl Sulfate Electrophoresis Versus Immunonephelometric Protein Marker Measurement Followed by Interpretation with the Knowledge-Based System MDI-LabLink

et al. 2004

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Increased urinary total protein is a nonspecific and unreliable marker of renal function. Analysis of the pattern of proteinuria, however, can provide information regarding the pathophysiologic changes in the affected nephrons. In physiologic proteinuria, the range of daily urinary protein excretion is typically 40 -80 mg/24 h with an upper limit of 150 mg/24 h. Albumin represents the main component (30 -40%), whereas IgG, light chains, and IgA represent 5-10%, 5%, and 3%, respectively, of urinary proteins. The remainder consists mostly of Tamm-Horsfall protein.Patterns of pathologic proteinuria may be classified as glomerular, tubular, prerenal, mixed, or postrenal, with glomerular patterns the most frequent. Total urine protein excretion can exceed 2 g/day, with albumin representing the main component (ϳ70%) and other large-molecularweight proteins, such as transferrin and IgG, accounting for the remaining 30%. Tubular proteinuria is characterized by the dominant excretion of low-molecular-weight proteins such as ␣ 1 -microglobulin (A1M) or retinol-binding protein (RBP), which correlate better with the extent of tubulo-interstitial damage than does determination of total 24-h protein concentrations (1 ).Urinary total protein is frequently undetectable in predominantly tubular kidney disease, and common chemical methods also often fail to detect urinary total protein in predominantly tubular kidney disease, in which albumin usually represents Ͻ30% of the total protein content (2-8 ). However, some renal tubular disorders or interstitial nephritis (e.g., when caused by antibiotics and other tubulo-toxic substances) are easily treatable. Prerenal proteinuria (Bence Jones proteinuria), attributable to overproduction of light chains in monoclonal diseases, or lysozymuria in patients with leukemia and the resulting overload of tubulo-interstitial reabsorption in the kidney often lead to secondary kidney damage. Mixed proteinuria presents with glomerular and tubular protein fractions in urine, i.e., high-and low-molecular-weight proteins. Postrenal proteinuria closely resembles glomerular proteinuria but can be identified by the presence of ␣ 2 -macroglobulin.Early approaches to the evaluation of proteinuria were based on sodium dodecyl sulfate (SDS) electrophoresis (9, 10 ). This method, however, is time-consuming, is at best semiquantitative, and has a high analytical detection limit well above the reference interval for most protein bands (Ϸ20 mg/L), and interpretation is investigator dependent. Alternatively, urinary marker proteins can be measured quantitatively by immunoturbidimetry or nephelometry.At least two knowledge-based systems for the further evaluation of proteinuria are available, UPES (11 ) and MDI-LabLink (4 ). MDI-LabLink, developed by Regeniter et al. (4 ), screens for proteinuria with few marker proteins (albumin and A1M) but uses additional marker proteins (IgG, transferrin, RBP, and ␤ 2 -microglobulin) to enable comparison with the SDS-polyacrylamide gel electrophoresis (PAGE) classification s...

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“…Turbidimetry and protein dye-binding assays are simple, readily automated, and are popular for clinics, but they characteristically lack a uniform response to different proteins. So urinary protein determinations are notoriously unreliable, and comparative evaluation of a range of assay methods has failed to establish a convenient method of choice (8,9). The use of an alternative protein calibrator prepared for sigma urinary protein lyophilizate (UPL) can improve the comparability of the results when applied to urine controls (10), but the potential value of the UPL as a protein calibrator for actual urine and CSF specimens remains a problem.…”

Section: Discussionmentioning

confidence: 99%

Application of an improved biuret method to the determination of total protein in urine and cerebrospinal fluid without concentration step by use of Hitachi 7170 auto‐analyzer

Xu¹,

Jiao²,

Zhu³

et al. 2001

Clinical Laboratory Analysis

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A biuret automated colorimetric assay for total protein in urine and cerebrospinal fluids was established. The procedures were as follows. Acidify all urine sample before analysis. Add precipitant Na(2)WO(4) to urine samples. After 10 min, centrifuge, decant the supernatant fluid, drain the inverted tubes on absorbent tissue, dissolve the precipitation with 0.1 mol/L NaOH, and finally adapt the reconstituted urine to the Hitachi 7170 analyzer. A cell-free cerebrospinal fluid sample produced by centrifugation can be inserted in an auto-analyzer for protein measurement directly. The program: mix 35 microl sample (CSF or reconstituted urine) and standard with 0.2 mol/L NaOH; incurable at 37 degrees C for 5 min, and real A1. Add concentrated biuret reagent, and 10 min later measure absorbance A2 at 546 nm vs. reagent blank. Secondary wavelength was 700 nm. The test results were calculated against a one-point standard. This biuret colorimetric method was relatively simple, fast, and accurate for the determination of protein in urine and cerebrospinal fluid, with a wide linearity extending from 0.125 g/L up to 6 g/L, had a good correlation with Benzethonium chloride turbidimetry technique, and was a practical routine method.

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Effects of low and high relative molecular protein mass on four methods for total protein determination in urine

Cited by 11 publications

References 18 publications

Renal Function in Adult Beta-Thalassemia/Hb E Disease

Renal Function in Adult Beta-Thalassemia/Hb E Disease

Patterns of Proteinuria: Urinary Sodium Dodecyl Sulfate Electrophoresis Versus Immunonephelometric Protein Marker Measurement Followed by Interpretation with the Knowledge-Based System MDI-LabLink

Application of an improved biuret method to the determination of total protein in urine and cerebrospinal fluid without concentration step by use of Hitachi 7170 auto‐analyzer

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