iCa and iMg in CVVHD: Method Agreement and Interpretation | Lucie Sanetrníková
ASSESSMENT OF IONIZED CALCIZM AND MAGNESIUM MEASUREMENT DURING CVVHD: METHOD COMPARISON AND CLINICAL RELEVANCE
(1) Department of Clinical Biochemistry and Haematology, Faculty of Medicine in Pilsen, Charles University and University Hospital, Pilsen
State-of-the-Art: Ionized magnesium (iMg²⁺) is a vital intracellular cation involved in neuromuscular conduction, enzyme activity, and calcium channel regulation. Despite its clinical relevance, it is not routinely measured—unlike ionized calcium (iCa²⁺). Emerging evidence suggests that iMg²⁺ may provide additional insights into pathophysiological changes during extracorporeal therapies such as continuous veno-venous hemodialysis (CVVHD). Since iMg²⁺ trends may diverge from those of iCa²⁺, its independent assessment could improve therapy optimization and patient monitoring in intensive care settings.
Objective: To compare ionized calcium measurements between two blood gas analyzers—GEM Premier 5000 (Werfen) and Stat Profile Prime® (NOVA Biomedical)—and to evaluate the correlation and agreement between temporal changes in iCa²⁺ and iMg²⁺ during CVVHD. The study also explores whether iMg²⁺ offers independent clinical value warranting routine monitoring.
Material and Methods: Samples from patients undergoing CVVHD were analyzed. iCa²⁺ and iMg²⁺ concentrations were measured using GEM Premier 5000 and Nova Biomedical analyzers. Method comparison included Bland–Altman analysis (both absolute and percentage differences) to assess agreement, and Passing–Bablok regression to evaluate systematic and proportional bias. Ninety-five percent confidence intervals (CI) were calculated for slope and intercept using robust regression and OLS modeling.
Results & Discussion: iCa²⁺ Comparison (GEM vs Nova): Bland–Altman analysis showed good agreement with a minimal mean difference. Passing–Bablok regression: intercept 0.15 (95% CI: 0.13–0.22), slope 0.87 (95% CI: 0.76–0.89) ΔiCa²⁺ vs ΔiMg²⁺ (Nova): Bland–Altman analysis of absolute differences revealed high variability. Additional Bland–Altman analysis using relative (%) differences showed no significant trend across the range of mean values, indicating no proportional bias. Passing–Bablok regression revealed a weak linear association: intercept 0.71 (95% CI: 0.62-0.81), slope 0.23 (95% CI: 0.11-0.40).
Conclusion: iCa²⁺ measurements showed strong analytical agreement across platforms. While the correlation between ΔiCa²⁺ and ΔiMg²⁺ was weak, the percentage-based Bland–Altman analysis showed no directional trend, suggesting both markers may reflect a shared underlying physiological mechanism during CVVHD. These findings indicate that routine measurement of iMg²⁺ may not provide substantial additional clinical information in this specific setting.
Study program: Master´s degree – General Medicine | Year of study: 4
ID: 1124
Effect of 24-hydroxylase | Anna-Marie Ševčíková
Effect of 24-hydroxylase with increasing vitamin D supplementation doses
Authors: Anna-Marie Ševčíková (1), Anna Vítková (1), Kristýna Otcovská (1)
Supervisor: Michal Jirásko (1)
(1) Department of Pharmacology and Toxicology, Faculty of Medicine in Pilsen, Charles University
State-of-the-Art: Vitamin D supplementation is generally well tolerated. Vitamin D can be toxic
in adults if administered daily in doses > 10,000 IU for several weeks to months, during which it
accumulates in the body and serum concentrations of around 500 nmol/l are reached. Overdose
is manifested by loss of appetite, nausea, fatigue, headache, diarrhea, sweating and paresthesias.
Laboratory findings include hypercalcemia, hypernatremia and increased urinary calcium and phosphorus excretion. The most serious complication are the calcium phosphate crystals in the kidneys and subsequent renal failure. Our body has a protective mechanism against vitamin D overdose. This protective function is performed by the enzyme 25-hydroxyvitamin D3-24-hydroxylase, an enzyme of the cytochrome P450 family, CYP24A1.
Objective: Our aim was to test the activity and capacity of 25-hydroxyvitamin D3-24-hydroxylase
in response to increasing daily doses of cholecalciferol supplementation at 1,000, 2,000, 4,000, and 8,000 IU.
Material and Methods: Participants: Thirty-five volunteers participated in this study. All participants
filled out a questionnaire about their health status, medications, and dietary habits during the last six months before being included in the study. Vitamin D was administered in increasing doses of 1000, 2000, 4000, 8000 IU/day, each for two months, and each two-month period of use was followed by 1 month without vitamin D use. Blood samples were collected before, after, and 30 days after each supplementation phase.
Measurements: All samples were measured using validated liquid chromatography-tandem
mass spectrometry (LC-MS/MS) method for the precise quantification of 25(OH)D₃ and 24,25(OH)₂D₃ in human serum (Agilent 6495 Triple Quadrupole LC/MS System, Agilent Technologies, USA).
Results & Discussion: All increases in levels of 25(OH)D₃ following supplementation and decreases
after discontinuation of supplementation were found to be statistically significant. The levels of 24,25(OH)₂D₃ followed a course of increases and decreases of 25(OH)D₃. The formation of 24,25(OH)₂D₃ metabolite was approximately at 10% of 25(OH)D₃ levels. This ratio did not change from the lowest to the highest measured 25(OH)D₃ levels.
Conclusion: With the vitamin D supplementation regimen used, 10 % 25(OH)D₃ was converted
to the 24,25(OH)₂D₃ metabolite. The conversion percentage was stable even at high concentrations
of 25(OH)D₃, demonstrating a sufficiently high capacity of 25-hydroxyvitamin D3-24-hydroxylase
for tested supplementation mode
Funding: Supported by the “Cooperatio” Program, research area Pharmaceutical Sciences.
Study program: Master´s degree – General Medicine | Year of study: 4
ID: 1100
Mushroom Bioactive Peptides | Alexandros Sepsas
Screening of Bioactive Peptides from Wild Mushrooms
Authors: Alexandros Sepsas (1), M. Marouf (1), C. Borsotti (1), V. Viltanioti (1), E. Fousková (1), Z. Tůma (2) and S. Pandey (1)
Supervisor: Shashank Pandey (1)
(1) Department of Pharmacology and Toxicology, Faculty of Medicine in Pilsen, Charles University (2) Biomedical Center, Faculty of Medicine in Pilsen, Charles University
State-of-the-Art: The global rise in antimicrobial resistance (AMR) continues to pose a significant threat to public health, as conventional antibiotics are increasingly losing effectiveness against a wide range of pathogenic bacteria. In this context, mushrooms have emerged as a promising natural reservoir of bioactive compounds, particularly peptides with potent antimicrobial properties. A small but growing body of research has identified several mushroom species as rich sources of antimicrobial peptides. For example, peptides isolated from Tapinella atrotomentosa, Pleurotus ostreatus, and Trametes versicolor have shown promising antibacterial activity against both Gram-positive and Gram-negative bacteria. These findings support the potential of further screening of wild mushroom species to discover novel.
Objective: Objective I: Screening of Bioactive Peptides (BAPs) for their Antimicrobial Activities. Objective II: Optimization of Protocol for Extraction of Bioactive Peptides from Mushroom.
Material and Methods: Screening of Bioactive Peptides (BAPs): Ten different wild mushroom species were collected from forests in the Pilsen region under the supervision of a professional mycologist. The identified species included Trametes versicolor, Pleurotus ostreatus, Flammulina velutipes, Tapinella atrotomentosa, Boletus edulis, Phaeolus schweinitzii, Hypholoma fasciculare, Rubroboletus satanas, Cantharellus cibarius, and Stereum subtomentosum. Bioactive peptides (BAPs) were extracted from each species and subsequently screened for antimicrobial activity. Optimization of Extraction Protocol: A solid-phase extraction (SPE)-based method was developed for the isolation of BAPs from wild mushrooms. To optimize the loading capacity of the SPE column, a synthetic peptide was used as a model compound.
Results & Discussion: Mass spectrometry analysis of BAPs extracted from the ten mushroom species revealed distinct peptide spectra for each species. The analysis confirmed that all detected peptides had molecular weights of less than 3 kDa. Among the tested BAPs, peptides extracted from Rubroboletus satanas exhibited notable antibacterial activity against Staphylococcus aureus, producing a zone of inhibition measuring 1.13 ± 0.21 mm. During the optimization of the solid-phase extraction (SPE) method, the loading capacity of the SPE column was determined to be 500 μg, with a peptide recovery rate of 46%. The optimized method proved effective for the extraction of peptides from various mushroom species. Nevertheless, species-specific variations were observed in both the yield and profile of the extracted BAPs.
Conclusion: In this study, BAPs from ten wild mushroom species were screened. BAPs extracted from Rubroboletus satanas showed antibacterial activity against Staphylococcus aureus. Moreover, SPE method was optimized for effective purification of BAPs.
Study program: Master´s degree – General Medicine | Year of study: 4
ID: 1138
Instagram for Engagement in Histology Education | Marek Navrátil
Student-Generated Instagram Content as a Tool for Engagement and Motivation in Histology and Embryology Classes
Authors: Marek Navrátil (1), Akvilé Baradulina (1)
Supervisor: Zbyněk Tonar (1)
(1) Department of Histology and Embryology, Faculty of Medicine in Pilsen, Charles University
State-of-the-Art: Social media is a highly competitive environment for attention. While often
suspected of reducing educational value due to accessible and entertaining formats, empirical
evidence suggests otherwise. Studies show that academic integration—feeling connected to
peers and institution—is a major factor in student success. Constructively designed social media
content can support this integration by building motivation, identity, and a sense of belonging.
Our project explores this potential through our own content creation for a departmental
Instagram account within a medical faculty, contextualized by a comparative analysis of communication
strategies used by leading institutions.
Objective: To evaluate the educational and emotional impact of Instagram videos we created
as part of medical education, and to compare them with selected posts from some medical
faculties worldwide to explore effective communication strategies that support motivation and
engagement.
Material and Methods: We created a series of Instagram reels for the Institute of Histology
and Embryology at the Faculty of Medicine in Pilsen (@histologie.embryologie), combining visual
design, humor, and educational messaging. The content was developed by us with creative autonomy
and supportive teachers’ input. An English-language version of the account (@histology.embryology) also exists for international students. We analyzed the posts for engagement and educational value. To broaden our perspective, we conducted a content analysis of 70 posts from seven medical education accounts—including our own. These included profiles of Harvard, Yale, Columbia, Stanford medical faculties, the central Charles University account, and @osmosismed (Elsevier). Posts were assessed by format, tone, and engagement.
Results & Discussion: Our Instagram reels—ranging from tutorials to parody—sparked strong
engagement (with some reaching over 1200 likes) and real interaction. The most successful was
“Do You Want to Pass Histology?”, a parody of Who Wants to Be a Millionaire? with a clear educational
message. Other formats included tutorials, countdowns, quizzes, polls, and expert interviews.
These formats worked because they spoke the students’ language—visually, emotionally, and academically. Our comparison with accounts from abroad confirmed: what may seem superficial can be a strategic way to foster engagement, motivation, and academic connection. Still, studies caution that social media—if misused—may increase stress or contribute to maladaptive coping. Effective communication requires balance, clarity, and intent.
Conclusion: Student-generated social media content, when guided by academic purpose, can
support motivation, integration, and professional identity. Thoughtfully curated posts may even
address aspects of the hidden curriculum—modelling empathy, inclusion, and respectful communication
in medical training.
Funding: The work was partially supported by Charles University, Project No. SVV 260 773.
Study program: Master´s degree – General Medicine | Year of study: 3
ID: 1123