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Biomedical subjects

Jiri Adamec

Publications and source records attributed to Jiri Adamec.

6 recordsLinked to original sources
PubMed2006

Inhibition of oxidative stress-induced invasiveness of cancer cells by Ganoderma lucidum is mediated through the suppression of interleukin-8 secretion.

Epidemiological studies suggest that the intake of natural/nutrient products is inversely related to cancer risk. While oxidative stress, generating reactive oxygen species, has been linked to cancer initiation and progression, dietary antioxidants have reduced the risk of certain cancers. Experimental studies have demonstrated that antioxidants and phytochemicals could prevent cancer metastasis, and antioxidants were suggested as adjuvants in cancer therapy. Ganoderma lucidum is an Asian medicinal mushroom that has been used for the past two thousand years for the treatment of various diseases, including cancer. G. lucidum is currently popular as a dietary supplement in the form of tea, powder or extract. We have previously demonstrated that G. lucidum suppresses growth, angiogenesis and invasiveness of highly invasive and metastatic breast cancer cells. The present study was undertaken to evaluate the effect of G. lucidum on oxidative stress-induced metastatic behavior of poorly-invasive MCF-7 breast cancer cells. We show that G. lucidum inhibits oxidative stress-induced migration of MCF-7 cells by the down-regulation of MAPK signaling. G. lucidum suppressed oxidative stress stimulated phosphorylation of extracellular signal-regulated protein kinases (Erk1/2), which resulted in the down-regulation of expression of c-fos, and in the inhibition of transcription factors AP-1 and NF-kappaB. The biological effect of G. lucidum on cell migration was mediated by the suppression of secretion of interleukin-8 from MCF-7 cells exposed to oxidative stress. In summary, our results suggest that G. lucidum inhibits the oxidative stress-induced invasive behavior of breast cancer cells by modulating Erk1/2 signaling and can be potentially considered as an antioxidant in adjuvant cancer therapy.

Antioxidants↗
PubMed2005

Data pre-processing in liquid chromatography-mass spectrometry-based proteomics.

MOTIVATION: In a liquid chromatography-mass spectrometry (LC-MS)-based expressional proteomics, multiple samples from different groups are analyzed in parallel. It is necessary to develop a data mining system to perform peak quantification, peak alignment and data quality assurance. RESULTS: We have developed an algorithm for spectrum deconvolution. A two-step alignment algorithm is proposed for recognizing peaks generated by the same peptide but detected in different samples. The quality of LC-MS data is evaluated using statistical tests and alignment quality tests. AVAILABILITY: Xalign software is available upon request from the author.

Algorithms↗
PubMed2005

An automated method for the analysis of stable isotope labeling data in proteomics.

An algorithm is presented for the generation of a reliable peptide component peak table from liquid chromatography-mass spectrometry (LC-MS) and subsequent quantitative analysis of stable isotope coded peptide samples. The method uses chemical noise filtering, charge state fitting, and deisotoping toward improved analysis of complex peptide samples. Overlapping peptide signals in mass spectra were deconvoluted by correlation with modeled peptide isotopic peak profiles. Isotopic peak profiles for peptides were generated in silico from a protein database producing reference model distributions. Doublets of heavy and light labeled peak clusters were identified and compared to provide differential quantification of pairs of stable isotope coded peptides. Algorithms were evaluated using peptides from digests of a single protein and a seven-protein mixture that had been differentially coded with stable isotope labeling agents and mixed in known ratios. The experimental results correlated well with known mixing ratios.

Algorithms↗
PubMed2002

Physical evidence that yeast frataxin is an iron storage protein.

Frataxin is a conserved mitochondrial protein required for iron homeostasis. We showed previously that in the presence of ferrous iron recombinant yeast frataxin (mYfh1p) assembles into a regular multimer of approximately 1.1 MDa storing approximately 3000 iron atoms. Here, we further demonstrate that mYfh1p and iron form a stable hydrophilic complex that can be detected by either protein or iron staining on nondenaturing polyacrylamide gels, and by either interference or absorbance measurements at sedimentation equilibrium. The molecular mass of this complex has been refined to 840 kDa corresponding to 48 protein subunits and 2400 iron atoms. Solution density measurements have determined a partial specific volume of 0.58 cm(3)/g, consistent with the amino acid composition of mYfh1p and the presence of 50 Fe-O equivalents per subunit. By dynamic light scattering, we show that the complex has a radius of approximately 11 nm and assembles within 2 min at 30 degrees C when ferrous iron, not ferric iron or other divalent cations, is added to mYfh1p monomer at pH between 6 and 8. Iron-rich granules with diameter of 2-4 nm are detected in the complex by scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. These findings support the hypothesis that frataxin is an iron storage protein, which could explain the mitochondrial iron accumulation and oxidative damage associated with frataxin defects in yeast, mouse, and humans.

Chromatography, Gel↗
PubMedDate not supplied

[The numerical Hatze-model: also qualified for calculations on children?].

The aim of this study was to find out whether the Hatze-model, which is specifically designed for adults, is suitable for calculations on children as well. By means of that program it is possible to calculate various parameters of the human body. After the collection of data and analysis of the results according to Hatze it becomes evident that this model provides good results only for the calculation of the total body mass. As regards the body segments, there are significant under- and overestimations. The same applies to the calculation of mean body density. Indeed there is a significant gender dimorphism indicating that girls have a higher fraction of body fat than boys. However, the values are far below those described in the literature. Due to the formula, the values of the centres of gravity are linear and congruent in both sides of the body. Interpretation of the results is difficult, as there are no valid reference values. Furthermore the program is not able to take characteristic shapes and proportions of children into account. For this reason 88% of the children are defined as either pregnant or obese. In summary, the study shows that the present model should not be used to calculate children and the human models have to be designed specifically for children.

Accidents, Traffic↗