Rafal Rozalski

Dr. Rafal Rozalski

orcid

Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

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

Representative Publications

View All Publications
15 August 2003
Verified
Journal Article
Closed access
DGDaniel Gackowski
Daniel Gackowski
ESElzbieta Speina
Elzbieta Speina
MZMaja Zielinska
Maja Zielinska
JKJanusz Kowalewski
Janusz Kowalewski
Rafal RozalskiRafal Rozalski
Rafal Rozalski
RORyszard Olinski
Ryszard Olinski

4 July 2015 in Biomarkers
Verified
Journal Article
Closed access
PDF file
Rafal RozalskiRafal Rozalski
Rafal Rozalski
DGDaniel Gackowski
Daniel Gackowski
ASAgnieszka Siomek-Górecka
Agnieszka Siomek-Górecka
MSMarta Starczak
Marta Starczak
MMMartyna Modrzejewska
Martyna Modrzejewska
RORyszard Olinski
Ryszard Olinski
Context: Oxidative stress linked with chronic inflammation is associated with etiology of the colorectal cancer. Objectives: To assess the diagnostic utility of urinary excretion of oxidatively modified DNA bases/nucleoside: 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) and 5-hydroxymethyluracil (5-hmUra). Materials and methods: Seventy-two healthy controls, 15 patients with adenomas and 56 colorectal cancer patients were recruited. Results: The receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) for all markers tested separately was <0.7. The combination of these modifications showed better diagnostic power (AUC = 0.778 for 8-oxoGua + 8-oxodG)/5hmUra ratio). Conclusion: Urinary DNA modifications may reflect the oxidative stress/chronic inflammation in colorectal cancer but diagnostic performance for early-detection is moderate.

13 August 2024 in Molecules
Verified
Journal Article
Open access
PDF file
Tomasz JelińskiTomasz Jeliński
Tomasz Jeliński
Maciej PrzybyłekMaciej Przybyłek
Maciej Przybyłek
Rafal RozalskiRafal Rozalski
Rafal Rozalski
KRKarolina Romanek
Karolina Romanek
DWDaniel Wielewski
Daniel Wielewski
Piotr CysewskiPiotr Cysewski
Piotr Cysewski
Deep eutectic solvents (DES) represent a promising class of green solvents, offering particular utility in the extraction and development of new formulations of natural compounds such as ferulic acid (FA). The experimental phase of the study undertook a systematic investigation of the solubility of FA in DES, comprising choline chloride or betaine as hydrogen bond acceptors and six different polyols as hydrogen bond donors. The results demonstrated that solvents based on choline chloride were more effective than those based on betaine. The optimal ratio of hydrogen bond acceptors to donors was found to be 1:2 molar. The addition of water to the DES resulted in a notable enhancement in the solubility of FA. Among the polyols tested, triethylene glycol was the most effective. Hence, DES composed of choline chloride and triethylene glycol (TEG) (1:2) with added water in a 0.3 molar ration is suggested as an efficient alternative to traditional organic solvents like DMSO. In the second part of this report, the affinities of FA in saturated solutions were computed for solute-solute and all solute-solvent pairs. It was found that self-association of FA leads to a cyclic structure of the C28 type, common among carboxylic acids, which is the strongest type of FA affinity. On the other hand, among all hetero-molecular bi-complexes, the most stable is the FA-TEG pair, which is an interesting congruency with the high solubility of FA in TEG containing liquids. Finally, this work combined COSMO-RS modeling with machine learning for the development of a model predicting ferulic acid solubility in a wide range of solvents, including not only DES but also classical neat and binary mixtures. A machine learning protocol developed a highly accurate model for predicting FA solubility, significantly outperforming the COSMO-RS approach. Based on the obtained results, it is recommended to use the support vector regressor (SVR) for screening new dissolution media as it is not only accurate but also has sound generalization to new systems.

9 October 2021 in Materials
Verified
Journal Article
Open access
PDF file
Piotr CysewskiPiotr Cysewski
Piotr Cysewski
Maciej PrzybyłekMaciej Przybyłek
Maciej Przybyłek
Rafal RozalskiRafal Rozalski
Rafal Rozalski
Solubility enhancement of poorly soluble active pharmaceutical ingredients is of crucial importance for drug development and processing. Extensive experimental screening is limited due to the vast number of potential solvent combinations. Hence, theoretical models can offer valuable hints for guiding experiments aimed at providing solubility data. In this paper, we explore the possibility of applying quantum-chemistry-derived molecular descriptors, adequate for development of an ensemble of neural networks model (ENNM), for solubility computations of sulfamethizole (SMT) in neat and aqueous binary solvent mixtures. The machine learning procedure utilized information encoded in σ-potential profiles computed using the COSMO-RS approach. The resulting nonlinear model is accurate in backcomputing SMT solubility and allowed for extensive screening of green solvents. Since the experimental characteristics of SMT solubility are limited, the data pool was extended by new solubility measurements in water, five neat organic solvents (acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, and methanol), and their aqueous binary mixtures at 298.15, 303.15, 308.15, and 313.15 K. Experimentally determined order of decreasing SMT solubility in neat solvents is the following: N,N-dimethylformamide > dimethyl sulfoxide > methanol > acetonitrile > 1,4dioxane >> water, in all studied temperatures. Similar trends are observed for aqueous binary mixtures. Since N,N-dimethylformamide is not considered as a green solvent, the more acceptable replacers were searched for using the developed model. This step led to the conclusion that 4-formylmorpholine is a real alternative to N,N-dimethylformamide, fulfilling all requirements of both high dissolution potential and environmental friendliness.

1 September 2014 in Biology of Reproduction
Verified
Journal Article
Closed access
JGJolanta Guz
Jolanta Guz
DGDaniel Gackowski
Daniel Gackowski
MFMarek Foksiński
Marek Foksiński
Rafal RozalskiRafal Rozalski
Rafal Rozalski
RORyszard Olinski
Ryszard Olinski
5-Methylcytosine is one of the most important epigenetic modifications and has a profound impact on embryonic development. After gamete fusion, there is a widespread and rapid active demethylation process of sperm DNA, which suggests that the paternal epigenome has an important role during embryonic development. To better understand the epigenome of sperm DNA and its possible involvement in a developing embryo, we determined epigenetic marks in human sperm DNA and in surrogate somatic tissue leukocytes; the analyzed epigenetic modifications included 5-methyl-2'-deoxycytidine, 5-hydroxymethyl-2'-deoxycytidine, and 5-hydroxymethyl-2'-deoxyuridine. For absolute determination of the modification, we used liquid chromatography with UV detection and tandem mass spectrometry techniques with isotopically labeled internal standards. Our analyses demonstrated, for the first time to date, that absolute global values of 5-methyl-2'-deoxycytidine, 5-hydroxymethyl-2'-deoxycytidine, and 5-hydroxymethyl-2'-deoxyuridine in sperm are highly statistically different from those observed for leukocyte DNA, with respective mean values of 3.815% versus 4.307%, 0.797 versus 2.945 per 10⁴ deoxynucleosides, and 5.209 versus 0.492 per 10⁶ deoxynucleosides. We hypothesize that an exceptionally high value of 5-hydroxymethyluracil in sperm (>10-fold higher than in leukocytes) may play a not yet recognized regulatory role in the paternal genome.

15 November 2016 in ChemistryOpen
Verified
Journal Article
Open access
PDF file
Rafal RozalskiRafal Rozalski
Rafal Rozalski
DGDaniel Gackowski
Daniel Gackowski
ASAgnieszka Siomek-Górecka
Agnieszka Siomek-Górecka
ZBZbigniew Banaszkiewicz
Zbigniew Banaszkiewicz
RORyszard Olinski
Ryszard Olinski
Active mechanism of DNA demethylation can be responsible for the activation of previously silenced genes. Products of 5‐methylcytosine oxidation are released into the bloodstream and eventually excreted with urine. Therefore, whole‐body epigenetic status can be assessed non‐invasively on the basis of the urinary excretion of a broad spectrum of epigenetic modifications: 5‐hydroxymethylcytosine (5‐hmCyt), 5‐formylcytosine (5‐fCyt), 5‐carboxycytosine (5‐caCyt), and 5‐hydroxymethyluracil (5‐hmUra). We have developed a specific and sensitive, isotope‐dilution, automated, online, two‐dimensional ultra‐performance liquid chromatography system with tandem mass spectrometry (2D UPLC–MS/MS) to measure 5‐hmCyt, 5‐fCyt, 5‐caCyt, and their deoxynucleosides in the same urine sample. Human urine contains all of the modifications except from 5‐formyl‐2′‐deoxycytidine (5‐fdC) and 5‐carboxy‐2′‐deoxycytidine (5‐cadC). A highly significant difference in the urinary excretion of 5‐(hydroxymethyl)‐2’‐deoxycytidine (5‐hmdC) was found between healthy subjects and colorectal cancer patients (3.5 vs. 7.8 nmol mmol−1 creatinine, respectively), as well as strong correlations between the majority of analyzed compounds.