Piotr Szefer

Prof. Dr. Piotr Szefer

Department of Food Sciences, Faculty of Pharmacy, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland

Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 May 2019 in Ecotoxicology and Environmental Safety
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JOJustyna Ośko
Justyna Ośko
MGMałgorzata Grembecka
Małgorzata Grembecka
IGIzabela Grochowska
Izabela Grochowska
Jerzy FalandyszJerzy Falandysz
Jerzy Falandysz
PSPiotr Szefer
Piotr Szefer

Verified
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AKAlicja Kotłowska
Alicja Kotłowska
Tomasz PuzynTomasz Puzyn
Tomasz Puzyn
KSKrzysztof Sworczak
Krzysztof Sworczak
Piotr StepnowskiPiotr Stepnowski
Piotr Stepnowski
PSPiotr Szefer
Piotr Szefer
Cushing’s syndrome (CS) is a disease which results from excessive levels of cortisol in the human body. The disorder is associated with various signs and symptoms which are also common for the general population not suffering from compound hypersecretion. Thus, more sensitive and selective methods are required for the diagnosis of CS. This follow-up study was conducted to determine which steroid metabolites could serve as potential indicators of CS and possible subclinical hypercortisolism in patients diagnosed with so called non-functioning adrenal incidentalomas (AIs). Urine samples from negative controls (n = 37), patients with CS characterized by hypercortisolism and excluding iatrogenic CS (n = 16), and patients with non-functioning AIs with possible subclinical Cushing’s syndrome (n = 25) were analyzed using gas chromatography-mass spectrometry (GC/MS) and gas chromatograph equipped with flame ionization detector (GC/FID). Statistical and multivariate methods were applied to investigate the profile differences between examined individuals. The analyses revealed hormonal differences between patients with CS and the rest of examined individuals. The concentrations of selected metabolites of cortisol, androgens, and pregnenetriol were elevated whereas the levels of tetrahydrocortisone were decreased for CS when opposed to the rest of the study population. Moreover, after analysis of potential confounding factors, it was also possible to distinguish six steroid hormones which discriminated CS patients from other study subjects. The obtained discriminant functions enabled classification of CS patients and AI group characterized by mild hypersecretion of cortisol metabolites. It can be concluded that steroid hormones selected by applying urinary profiling may serve the role of potential biomarkers of CS and can aid in its early diagnosis.

13 July 2010 in Environmental Monitoring and Assessment
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MMMałgorzata Misztal-Szkudlińska
Małgorzata Misztal-Szkudlińska
PSPiotr Szefer
Piotr Szefer
PKPiotr Konieczka
Piotr Konieczka
JNJacek Namiesnik
Jacek Namiesnik
Total mercury (Hg) concentrations were determined by CV-AAS in selected tissues (liver, kidney, and muscle) of the Great Cormorant and some fish species (herring, ruffe, European smelt, tench, roach, Crucian carp, and Prussian carp) from the Vistula Lagoon ecosystem (Poland). Significant correlations between Hg concentrations in the kidneys and muscle of cormorants (U test, p < 0.05) were found; levels of the metal were highest in the birds’ liver and kidneys. Total Hg concentrations in the fish decreased in the following order: roach > Prussian carp > Crucian carp > tench > European smelt > ruffe > herring. The biomagnification factor of Hg for the cormorant relative to the fish decreased in the following sequence: herring > ruffe > European smelt > tench > Crucian carp > roach = Prussian carp. It was significantly greater than unity, especially for the cormorant–herring trophic relationship. This implies that Hg is biomagnified in the cormorant in relation to its prey.

16 September 2016 in Biological Trace Element Research
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JOJustyna Ośko
Justyna Ośko
MGMałgorzata Grembecka
Małgorzata Grembecka
TCTomasz Ciesielski
Tomasz Ciesielski
TFTrond Peder Flaten
Trond Peder Flaten
PSPiotr Szefer
Piotr Szefer
The aim of this study was to evaluate the elemental composition of black tea samples and their infusions in view of their geographical origin. In total, 14 elements were analyzed, 13 (Ca, K, Mg, Na, Mn, Fe, Zn, Cu, Cr, Ni, Co, Cd, and Pb) by flame atomic absorption spectrometry, and P by UV-Vis spectrometry, after mineralization of samples. It was found that K was the most abundant macroelement in the analyzed samples, whereas among microelements, the highest concentration was found for Mn. Based on the obtained data, the percentage of elements leached into the infusions as well as the daily elemental intake from tea were calculated. The daily intake from tea was compared to the recommended daily allowances (RDAs), and the highest percentages of the RDAs were found for Mn (15 %) and Co (10 %). To study the relations between elemental composition and country of origin of samples, factor analysis and cluster analysis were applied. These multivariate techniques proved to be efficient tools able to differentiate samples according to their provenance as well as plantation within the common regions.

2 April 2016 in Biological Trace Element Research
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JOJustyna Ośko
Justyna Ośko
MGMałgorzata Grembecka
Małgorzata Grembecka
PSPiotr Szefer
Piotr Szefer
This study concerns application of flame atomic absorption spectrometry (FAAS) in assessment of macro- and microelement and toxic metal levels (Mg, Ca, K, Na, Mn, Cu, Fe, Zn, Cr, Ni, Co, Cd and Pb) in dark (Pu-erh) and fruit tea leaves and their infusions. Phosphorus was also determined in the form of phosphomolybdate by spectrophotometric method. The reliability of the method was checked using three certified reference materials. The results of analysis were in agreement with the certified values, with analytical recovery ranging from 86 to 113 %. Significant correlations (p < 0.001) were found between concentrations of P, Zn, K, Ni, Fe, Co, Cr, and Pb in Pu-erh tea, whereas in fruit tea, such interdependences were found between Mg, Fe, P, Ni, and Co. Kruskal-Wallis test results have related differences in Pu-erh tea quality as well as technological processing of fruit tea to their mineral composition. In order to characterize tea elemental content, chemometric techniques such as factor analysis (FA) and cluster analysis (CA) were used. Their application allowed on differentiation of samples in view of the fermentation type, technological processing, and overall quality.

1 February 2022 in Applied Sciences
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MGMałgorzata Grembecka
Małgorzata Grembecka
PSPiotr Szefer
Piotr Szefer
The study aimed to evaluate fourteen elements’ profiles of legumes and oilseeds, of various geographical origins, available on the Polish market. They were determined by flame atomic absorption spectrometry (F-AAS) and spectrophotometric method (phosphorus) in 90 analytical samples. In general, legumes were characterized with lower mean concentrations of Ca, Mg, Na, P, Zn, Cu, Fe, Mn, and Cr than oilseeds. However, the concentrations ranges within each group differed significantly (p < 0.05). Calcium content varied between 6.2 and 243.5 mg/100 g in legumes and 38.4 and 2003 mg/100 g in oilseeds. In the case of Fe, its concentration was between 1.99 mg/100 g and 10.5 mg/100 g in legumes, and 2.05 mg and 12.15 mg/100 g in seeds. All the samples were characterized with Pb concentration below the LOQ (30 µg/100 g). In the case of Cd, its presence (>LOQ, 9 µg/100 g) was confirmed in one sample of legumes (soybean) and five samples of seeds (poppy seeds, roasted linseeds, hulled wheat, linseed, and sunflower seeds). The detected Cd content in every sample, except for soybean and hulled wheat, exceeded the permissible European standards. According to Kruskal-Wallis test results, Mg, Na, K, P, Zn, Cu, Mn, Cr, and Cd content depended on the type of the analyzed product, while in the case of botanical provenance such relationship was recorded for most of the analyzed components, except for Fe, Cr, and Co. Factor and cluster analyses classified the analyzed samples in view of their botanical species and type based on their mineral composition.