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Ranko Škrbić

Društvene mreže:

Relja Suručić, Maja Travar, Tatjana Kundaković Vasović, Jelena S Radović Selgrad, Ljiljana T. Suručić, Milan Momčilović, Miloš P. Stojiljković, R. Škrbić

Background/Objectives: This study investigates the antimicrobial properties of pomegranate peel extract (PoPEx) and its major polyphenolic constituents against Gram-positive and Gram-negative bacteria, employing six clinical isolates of Staphylococcus aureus and five isolates of Escherichia coli. The study further aims to elucidate mechanisms of action through molecular docking and transport studies. Methods: Chemical composition was analyzed using liquid chromatography–mass spectrometry (LC–MS). Antimicrobial activity was determined by the broth microdilution method. Molecular docking was performed with the AutoDock Vina algorithm, and transport studies through porin channels were carried out using Caver software. Results: PoPEx showed stronger activity against Gram-positive (MICs 15.62–500.00 μg/mL) than Gram-negative bacteria (MICs 125.00–500.00 μg/mL). Punicalagin was most active against S. aureus, while gallic acid was most effective against E. coli. Docking revealed high affinities of punicalagin and punicalin, whereas transport studies highlighted the advantage of smaller phenolics like gallic acid in crossing porins. Conclusions: Larger tannins exhibited strong target binding but limited porin permeability, reducing efficacy in Gram-negative bacteria. These findings provide insights into structure–activity relationships of pomegranate polyphenols and support their potential as natural antimicrobial agents.

Zoran Matković, M. Gajić Bojić, U. Maličević, A. Krivokuća, N. Mandić-Kovačević, S. Uletilović, L. Amidžić, Sanja Jovičić, M. Barudžija et al.

Acute mesenteric ischemia (AMI) is a life-threatening condition characterised by oxidative stress, inflammation, apoptosis, and necrosis of intestinal epithelial cells. Different drugs with vasoactive, antioxidant, and anti-inflammatory properties have been used to treat AMI. Levosimendan is a drug with proven anti-ischemic effects used in the management of acute congestive heart failure. This study evaluated the protective effects of levosimendan pretreatment on intestinal, as well as lung, heart, and kidney tissue in a rat model of mesenteric artery ischemia/reperfusion (I/R) injury. Male Wistar rats (N = 24) were divided into four groups: control, I/R, levosimendan (LS) 1 mg/kg i.p, and LS + I/R (1 mg/kg i.p. 30 min before injury). I/R by itself caused elevation of oxidative markers (thyobarbituric acid reactive species (TBARS), hydrogen peroxide (H2O2), super oxide anjon radical (O2−), and nitrogen dioxide (NO2−)), induced inflammation (macrophage infiltration and Interleukin-6 (IL-6) production), and apoptosis (nuclear factor kappa light-chain enhancer of activated B cells (NF-κB), cleaved caspase-3 (CC3), and terminal deoxy-nucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL)). Levosimendan pretreatment significantly reduced oxidative stress markers and enhanced antioxidant defences (catalase (CAT), reduced glutathione (GSH), and superoxide dismutase (SOD)). Histological analysis revealed reduced mucosal damage and preserved goblet cells in intestinal tissue. Similar protective effects of levosimendan were observed in other organs such as lung, heart, and kidney. Immunohistochemistry showed reduced epithelial apoptosis and upregulation of antioxidant and anti-inflammatory proteins. These findings highlight levosimendan’s ability to protect mesenteric I/R tissue injury and multi-organ damage by suppressing oxidative stress, inflammation, and apoptosis, emphasising its therapeutic potential in clinical settings.

Dragan M. Djuric, Zorislava Bajic, Nina Radisavljevic, Tanja Sobot, Slavica Mutavdžin Krneta, S. Stanković, R. Škrbić

As the leading cause of global mortality, cardiovascular diseases demand improved and innovative strategies for early detection and risk assessment to enhance prevention and timely treatment. This comprehensive review examines the potential of combining high-sensitivity cardiac troponins (hs-cTns) and homocysteine (Hcy) as complementary biomarkers for enhanced cardiovascular risk prediction. hs-cTn assays have revolutionized cardiovascular diagnostics by enabling the detection of minimal myocardial injury, improving early diagnosis of acute coronary syndrome, and providing robust prognostic information in both symptomatic and asymptomatic populations. Hcy, while established as a marker of vascular dysfunction, presents an interpretative challenge due to multiple confounding factors and inconsistent therapeutic responses. Emerging evidence demonstrates significant correlations between elevated Hcy and troponins across various clinical conditions, suggesting that their combined assessment—reflecting both myocardial injury and vascular dysfunction—may improve cardiovascular risk stratification. While initial findings are promising, additional studies are required to validate the clinical value of the combined marker approach. Future development of personalized interpretation algorithms, and multi-marker panels incorporating these biomarkers, may significantly advance cardiovascular medicine and enable more effective population-specific risk management strategies.

Sonja T. Marinković, Tanja Sobot, Ž. Maksimović, Ðorđe Ðukanović, S. Uletilović, N. Mandić-Kovačević, Sanja Jovičić, Milka Matičić, M. Gajić Bojić et al.

Autonomic imbalance is one of the major pathological disturbances in chronic heart failure (CHF). Additionally, enhanced oxidative stress and inflammation are considered to be the main contributors to the disease progression. A growing body of evidence suggests cholinergic stimulation as a potential therapeutic approach in CHF, since it corrects the autonomic imbalance and alters the inflammatory response via the cholinergic anti-inflammatory pathway. Although previous research has provided some insights into the potential mechanisms behind these effects, there is a gap in knowledge regarding different cholinergic stimulation methods and their specific mechanisms of action. In the present study, an isoprenaline model (5 mg/kg/day s.c. for 7 days, followed by 4 weeks of CHF development) was used. Afterwards, rats received pyridostigmine (22 mg/kg/day in tap water for 14 days) or no treatment. Pyridostigmine treatment prevented the progression of CHF, decreasing chamber wall thinning (↑ PWDd, ↑ PWDs) and left ventricle dilatation (↓ LVIDd, ↓ LVIDs), thus improving cardiac contractile function (↑ EF). Additionally, pyridostigmine improved antioxidative status (↓ TBARS, ↓ NO2−; ↑ CAT, ↑ GSH) and significantly reduced cardiac fibrosis development, confirmed by pathohistological findings and biochemical marker reduction (↓ MMP2, ↓ MMP9). However, further investigations are needed to fully understand the exact cellular mechanisms involved in the CHF attenuation via pyridostigmine.

Radovan Kukobat, R. Škrbić, Suzana Gotovac Atlagić, B. Malinović, D. Bodroža

Dissolution of water-insoluble drugs is an important challenge in drug delivery. Adsorbing water-insoluble drugs onto nanoporous carriers such as zeolites can improve drug dissolution.  The drug molecules adsorbed in a thin layer onto nanoporous carriers are fully exposed to the solvent, enhancing the dissolution process. This presentation will give new insights into the adsorption of water-insoluble letrozole drug onto the nanoporous clinoptilolite zeolite from a nanoscale-science point of view based on experimental and theoretical considerations. Adsorption of the letrozole drug on clinoptilolite zeolite will be conducted from the colloidal dispersion state. The amount of letrozole adsorbed in a monolayer will be evidenced by thermogravimetric measurements, while optical spectroscopy techniques will reveal the interactions of the letrozole drug on the nanoporous zeolite framework. Positive adsorption energy at the letrozole-clinoptilolite interface calculated using density functional theory models suggests a small affinity for letrozole adsorption, suggesting the letrozole release is more favorable than the adsorption process. Thus, this presentation will show new possibilities in adsorption and dissolution of water-insoluble drugs.

Vedrana Barišić, T. Kovačević, Maja Travar, Ana Golić Jelić, P. Kovačević, Dragana Milaković, R. Škrbić

Background/Objectives: Improper use of systemic antibiotics remains a significant concern in hospital settings, contributing to increased antimicrobial resistance and suboptimal clinical outcomes. The COVID-19 pandemic exacerbated this issue. This study aimed to evaluate long-term trends in antibiotic utilization in low-resource settings at a tertiary care teaching hospital, focusing specifically on the changes before, during, and after the COVID-19 pandemic. Methods: This retrospective observational study analyzed antibiotic utilization data from the University Clinical Centre of the Republic of Srpska over ten years (2015–2024). Antibiotic consumption was expressed in defined daily doses (DDD) per 100 bed-days, and compared across three periods: pre-COVID-19 (2015–2019), COVID-19 (2020–2022), and post-COVID-19 (2023–2024). Additionally, antibiotic use was categorized according to the WHO AWaRe classification. Results: Antibiotic utilization peaked during the COVID-19 period, with the highest rate observed in 2021 (91.5 DDD/100 bed-days), despite a decrease in hospital admissions. The most frequently used antibiotics were cephalosporins, penicillins, and metronidazole. A significant increase in the use of azithromycin, meropenem, piperacillin/tazobactam, vancomycin, and colistin was noted during the COVID-19 and post-COVID-19 periods (p < 0.05), along with a notable decline in penicillin use. Watch and Reserve antibiotic use rose significantly (p < 0.05), while Access group use fell from 67% to 49.2%. Conclusions: These findings underscore the lasting impact of the COVID-19 pandemic on antibiotic prescribing patterns and emphasize the urgent need for strengthened antimicrobial stewardship efforts to ensure rational antibiotic use and combat antimicrobial resistance.

Sanja Jovičić, Ivan R. Nikolic, L. Amidžić, Vesna Ljubojević, M. Barudžija, R. Škrbić

Background: The process of prenatal hematopoiesis occurs in various anatomical locations, including the placenta. The placenta is not merely a temporary hematopoietic reservoir, but it is one of the key sites for the synthesis of hematopoietic stem cells (HSCs). This study aimed to investigate the presence, distribution, and immunoprofiles of HSCs in the human placenta during different gestational periods. Materials and Methods: Placental samples of different gestational ages (first, second, and third trimesters) were analyzed using classical hematoxylin and eosin staining and immunohistochemical staining for CD34, CD117, and CD41 markers, with HSC quantification through numerical areal density (NA). Results: Highly immunoreactive CD34 HSCs were present in placentas throughout gestation, while highly immunoreactive CD117 and CD41 HSCs were observed during the first two trimesters. In the first trimester, HSCs were found within the lumen of blood vessels and as individual cells in the mesenchyme of chorionic villi. With advancing gestation, the number of HSCs in the mesenchyme of chorionic villi increased. Conclusions: Immunoreactive CD34, CD117, and CD41 cells are present in significant proportions in various parts of the placenta throughout gestation, indicating that the placenta provides a substantial proportion of HSCs for hematopoiesis.

T. Milivojac, M. Grabež, L. Amidžić, A. Prtina, A. Krivokuća, U. Maličević, M. Barudžija, Milka Matičić, S. Uletilović et al.

Introduction This study aimed to investigate the anti-inflammatory, antioxidant, and anti-apoptotic properties of ursodeoxycholic (UDCA) and chenodeoxycholic (CDCA) bile acids in a rat model of endotoxin (lipopolysaccharide, LPS)-induced acute lung injury (ALI). Methods The study included six groups of Wistar rats exposed to different pretreatments. The control and endotoxin groups were pretreated with propylene glycol, a solvent for bile acids, while the other groups received UDCA or CDCA for 10 days. On the 10th day, an endotoxin injection was given to evaluate the impact of these pretreatments. Lung tissue sections were analyzed by immunohistochemistry, targeting the pro-inflammatory marker nuclear factor kappa B (NF-κB), the anti-apoptotic marker B-cell lymphoma 2 (BCL-2), pro-apoptotic markers BCL-2-associated X protein (BAX) and caspase 3, as well as the aquaporins 1 and 5 (AQP1 and AQP5). Oxidative stress was assessed in bronchoalveolar lavage fluid (BALF). Results and discussion This study demonstrates that UDCA and CDCA can mitigate endotoxin-induced lung injury in rats. These effects are achieved through modulation of AQP1 and AQP5 expression, reduction of oxidative stress, regulation of apoptotic pathways (BAX, caspase 3, BCL-2), and attenuation of pro-inflammatory activity of NF-κB. Although the results indicate a significant association between the expression of these proteins and histopathological changes, the potential influence of additional factors cannot be excluded. These findings suggest that UDCA and CDCA provide lung protection by acting through complex mechanisms involving inflammatory, oxidative, and apoptotic pathways.

Zorislava Bajic, Tanja Sobot, A. Smitran, S. Uletilović, N. Mandić-Kovačević, T. Cvjetković, U. Maličević, Bojan Stanetić, Đ. Đukanović et al.

Background: Myocardial injury (MI) is characterized by an increased level of at least one cardiac troponin. Experimental MI can be induced by isoprenaline, a β-adrenergic agonist, and it can lead to heart failure (HF). Liraglutide is glucagon-like 1 peptide receptor agonist used in diabetes management, but it has anti-inflammatory and antioxidative effects, which can be beneficial in treatment of HF. The aim of this study was to investigate the effects of liraglutide on isoprenaline-induced MI and prevention of HF. Methods: Male Wistar albino rats were divided into four groups: Con—received saline the first 2 days + saline the next 7 days; Iso—isoprenaline the first 2 days + saline the next 7 days; Lir—saline the first 2 days + liraglutide the next 7 days; Iso + Lir—isoprenaline the first 2 days + liraglutide the next 7 days. On day 10, blood samples were taken for biochemical analysis and oxidative stress marker evaluation, and hearts were isolated for pathohistological analysis. Cardiac function was assessed by electrocardiography (ECG) and echocardiography (ECHO). Results: Liraglutide treatment significantly attenuated oxidative stress, repaired ECG and ECHO parameters, and mitigated myocardial morphological changes induced by isoprenaline. Conclusions: Liraglutide restores cardiac function in isoprenaline-induced HF.

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