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Biomedical subjects

L Prencipe

Publications and source records attributed to L Prencipe.

31 records · Page 2Linked to original sources
PubMed1980

Use of 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone chromogenic system in direct enzymic assay of uric acid in serum and urine.

A new direct colorimetric procedure for uric acid assay in serum or urine is described, utilizing a 3,5-dichloro-2-hydroxybenzene sulfonic acid/4-aminophenazone chromogenic system in the presence of horseradish peroxidase and uricase from Aspergillus flavus. This chromogen system has a high absorptivity, affording useful results with sample/reagent volume ratios as low as 0.025. The procedure is applicable to serum, plasma, or diluted urine. A single working reagent is used; the reaction is complete in less than 15 min at room temperature. The red dye formed is measured at 520 nm; a blank sample measurement is not needed. The standard curve for the method is linear for uric acid concentrations up to 1500 mumol/L. Average analytical recovery of uric acid in human sera and urine exceeded 99%; within-run and between-run precision studies showed CV's of less than or equal to 1.2 and less than or equal to 2.2%, respectively. The new procedure correlated well with the uricase/catalase and uricase/ultraviolet methods. The method is suitable for automation.

Aminopyrine↗
PubMed1979

A homozygote for a serum albumin variant of the fast type.

A healthy, 10-year-old male born in Milano to a family from Southern Italy (Puglia) was found to be a homozygote for an albumin variant of the fast type. His parents are half-first cousins. Their common grandfather, the parents, one sister, and three brothers of the child were all heterozygotes for the same albumin variant. This seems to be the first case of a homozygote for a fast albumin variant described in Europe.

Alleles↗
PubMed1978

The 4-hydroxybenzoate/4-aminophenazone chromogenic system used in the enzymic determination of serum cholesterol.

A single reagent, containing cholesterol oxidase, cholesterol esterase, peroxidase, 4-hydroxybenzoate, and 4-aminophenazone, is used in determining serum cholesterol. Analysis time is 15 min, and the standard curve is linear to 6.0 g/liter. Analytical recovery of cholesterol was 100.1 +/- 0.4%. Within-run precision (CV) was less than or equal to 1.4 1.4%, between-run less than or equal to 4.8%. Comparison with results by a Liebermann Burchard method [Clin. Chim. Acta 5, 637 (1960)] gave a linear regression of y = 1.08x--0.05, with a correlation coefficient (r) of 0.985. Comparison with the Roeschlau enzymic method [J. Clin. Chem. Clin. Biochem, 12, 226 (1974)] gave y = 1.02x + 0.01 (r = 0.958). Comparison with the enzymic method of Allain et al. [Clin. Chem. 20, 470 (1974)] gave y = 1.01x--0.00 (r = 0.995). The following substances do not interfere up to the indicated concentrations (mg/liter): hemoglobin (5000), bilirubin (100), reduced glutathione (150), l-cysteine (400), urea (3000), creatinine (200), uric acid (200), d-glucose (10000), L-ascorbic acid (50), acetylsalicylic acid (500), L-DOPA (10), ergothioneine (1000), 2,5-dihydroxybenzoic acid (20), and 3,4-dihydroxybenzoic acid (10). Stored in an amber-colored bottle, the working reagent is stable for three months at 2--8 degrees C and for three weeks at 25 degrees C.

Aminopyrine↗
PubMed1978

[Emerson-Trinder reaction: study of various chromogens and analyses of the principle interferences (author's transl)].

Several phenolic compounds and aromatic amines were tested with a system consisting of hydrogen peroxide, peroxidase and 4-aminophenazone for their chromogenic activity in the Emerson-Trinder reaction: sulphonated 2,4-diclorophenol had the greatest activity, about 4 times that of unsubstituted phenol. The mechanism of action of serum components (serum proteins, bilirubin and ascorbic acid) which can interfere in the Emerson-Trinder reaction was also investigated by the same analytical system. Binding of phenolic compounds to serum was found to be responsible for protein interference: this can be overcome by increasing the phenolic compounds concentration. The interference by bilirubin and ascorbic acid is due to hydrogen peroxide consumption, in competition with the chromogenic substrate.

Aminopyrine↗
PubMed1978

[Enzymatic determination of uric acid in serum with the trinder reaction (author's transl)].

We describe a direct colorimetric method for the enzymatic assay of uric acid. 50 microliters serum aliquots are incubated for 30 min with a diluted hexacyanoferrate solution, to remove interference by non-specific reducing agents. Uric acid is then oxidized to allantoin in the presence of uricase (Aspergillus flavus), with the simultaneous production of hydrogen peroxide; this is measured by a modified Emerson-Trinder reaction, in which phenol has been replaced by sulphonated 2,4-dichlorophenol, a more sensitive chromogen. The method gives linear results up to 20 mg of uric acid/100 ml.

Colorimetry↗