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Biomedical subjects

A Bobrowski

Publications and source records attributed to A Bobrowski.

At least 19 recordsLinked to original sources
PubMed2005

Application of a bismuth film electrode to the voltammetric determination of trace iron using a Fe(III)-TEA-BrO3- catalytic system.

A sensitive catalytic voltammetric method for determining trace iron at a bismuth film electrode (BiFE) is described. The method is based on the cathodic reduction of the Fe(III)-triethanolamine (TEA) complex to Fe(II). It has been proved that the addition of KBrO3 causes rapid oxidation of Fe(II) and TEA, and therefore results in a large increase in the analytical signal from Fe(III) when TEA is placed in alkaline solution. When TEA was present in the solution, operating the BiFE under optimized conditions yielded a stable catalytic voltammetric response for iron, with high sensitivity (0.88 muA muM(-1)), good precision (RSD=3.9%) and a low detection limit (7.7 x 10(-9) M), obtained without any preconcentration procedure. Possible interferences from the coexisting ions and surface-active substances were investigated. Finally, the method was applied with satisfactory results to the determination of iron in certified reference river water samples.

Journal Article↗
PubMed2003

A note on distributions of times to coalescence, under time-dependent population size.

Expressions for marginal distributions of times in the time-varying coalescence process are derived. The proposed method allows also for computation of joint probability distribution for pairs, triples, etc. of coalescence times. The expressions derived are useful for (1) extending several statistics from time constant to time-varying case, (2) increasing efficiency and accuracy of simulations in time-varying evolution, and (3) debugging coalescence simulation software.

Animals↗
PubMed2001

Determination of arsenic in water--quality assurance and calculation of metrological characteristics.

Arsenic is a toxic element, acting as a nerve poison and proven carcinogen. Its main source for humans is drinking water where the most important are arsenic (V) compounds. With respect to the Slovak standard, in force since 1998, the maximum tolerable value is defined as the important characteristic of drinking water. If the value 0.01 mg.l-1 of arsenic is exceeded, water is not drinkable. The mentioned standard defines criteria for precision of the arsenic determination and the corresponding limit of detection--being 10% of the maximum tolerable value. Arsenic content in the drinking water samples was measured by the AAS method. Internal Quality Control for analysis by the ETA AAS method was based on the harmonised guidelines recommended by IUPAC, ISO and AOAC. The following metrological characteristics were calculated: precision, accuracy, and the yield of the arsenic standard addition to the studied sample--matrix spike and analytical spike. In addition to it, a thorough study of the limit of detection, LOD, and the limit of quantification (determination), LOQ, was performed. The LOD and LOQ values were calculated in the traditional way as well as by the ULA technique, newly recommended by IUPAC. In the latter case, the calculated LOD value was close to the demanded 10% limit of the maximum tolerable value, which is 1 microgram.l-1 As. The repeatability and reproducibility, found at two concentration levels 56.02 +/- 0.73 micrograms.l-1 and 6.0 +/- 0.9 microgramsl-1, were 3.2% and 3.9%, respectively, and 7.1% and 9.8%, respectively. Trueness of the applied AAS method was proven satisfactory on the reference material SRM 1643 Trace Elements in Water.

Arsenic↗
PubMed1988

[Fine-needle biopsy in the early diagnosis of thyroid neoplasms].

Among the patients directed to the Department of Endocrinology of the Institute of Internal Medicine for diagnostic examinations of the thyroid, 726 (647 women and 79 men, of age between 16 and 79 years) were qualified to surgery after scintigraphic detection of cold nodules. From this group, 474 patients had thin-needle biopsy specimens taken for cytologic examination. The results of the latter examinations have been compared with those of histologic examination performed on the tissue removed during surgery. The occurrence of a malignant tumor (in 99.1%--thyroid cancer) was found in 108 patients (22.8%) from the group having thin-needle biopsy performed. Comparison of the results of cytologic examination with those of postoperative histologic examination demonstrated low sensitivity of biopsy examination (50.0%), as opposed to high specificity (96.2%) and high accuracy (85, 3%). Analysis of the false-negative results (54/108) revealed that the main causes of errors are difficulties in differentiation of adenoma from follicular carcinoma. Widening of the indications to surgery by a group of patients with adenoma will increase sensitivity to 84.8% and will require including into the operated group of about 50% of patients with scintigraphically diagnosed cold nodules: The introduction of the new term: "urgent strumectomy", has been proposed; also a diagnostic algorithm, useful for early diagnosis of malignant tumors of the thyroid, has been discussed.

Adolescent↗