Applicability ofMathematicalModels in Defining the Behaviour Kinetics Distinction Among Microbial Strains

Mathematical models were applied to define the behaviour kinetics distinction among microbial strains. In the first series of experiments the growth kinetics of microbial colonies of several S. rimosus mutant strains cultivated on agar plates were compared. Then, the interest was focused on the chosen two strains, in order to express mathematically their differences with respect to their colony growth and antibiotic biosynthesis kinetics. Finally, the behaviour of selected three S. rimosus derivative strains at different culture conditions was subjected to the study, with an aim to define strain distinction parameters. Mathematical models based on the three-dimensional growth concept and describing the microorganism growth, substrate uptake and antibiotic biosynthesis kinetics were developed. The computer simulation was applied to verify the applicability of mathematical models. The excellent agreement of computer simulation with experimental data confirmed the hypothesis that the kinetics parameters can be successfully applied to define the behaviour distinction among different S. rimosus strains. In the case of selected three strains, S. rimosus R6–500, S. rimosus MV9R-1 and MV9R-2, it was established that they can be distinguished by their growth kinetics parameters, their substrate uptake kinetics parameters and their antibiotic biosynthesis kineticsparameters. The strain S. rimosus R6–500 showed to be superior with respect to all kinetics parameters, the strain S. rimosus MV9R-2 showed to be slightly inferior to it, whereas the strain S. rimosus MV9R-1 showed to be inferior with respect to the both mentioned strains, especially because it showed the pronounced active biomass reduction rate at all investigated culture conditions. Based on these and the corresponding previous results one can conclude that appropriate mathematical models can be recommended for defining parameters of microbial behaviour distinction among different microbial strains of S. rimosus species

Optimizacija uslova mikrotalasne ekstrakcije fenolnih jedinjenja ploda divlje trešnje (Prunus Avium L.)

The aim of this study was to optimize the conditions of microwave extraction for determining the content of the total flavonoids of wild cherry fruits (Prunus avium L.). The conditions that are optimized are the percent of methanol, solvent to liquid ratio, the time and temperature of the extraction. Based on the experimental design and software package Design Expert 7.0.0, the optimal conditions for this type of extraction were determined: methanol percentage 70%, solid to liquid ratio 0.03 g / mL, extraction time 1.80 min and temperature 78 ° C. Using the DPPH method, the antioxidant activity of the extract obtained under optimal conditions was determined (IC50 = 5.14 mg mL-1).Cilj ovog rada bila je optimizacija uslova mikrotalasne ekstrakcije za određivanje sadržaja ukupnih flavonoida ploda divlje trešnje (Prunus avium L.). Uslovi koji su optimizovani su procenat metanola, odnos mase uzorka i rastvarača, vreme i temperatura ekstrakcije. Na osnovu eksperimentalnog dizajna i softverskog paketa Design Expert 7.0.0., određeni su optimalni uslovi ove vrste ekstrakcije i to su: procenat metanola 70%, odnos mase uzorka i rastvarača 0,03 g/mL, vreme ekstrakcije 1,80 min i temperatura 78 °C. Primenom DPPH metode ispitana je antioksidativna aktivnost ekstrakta dobijenog pod optimalnim uslovima (IC50 = 5,14 mg mL-1)

Epigallocatechin-3-gallate induces mesothelioma cell death via H2O2-dependent T-type Ca2+ channel opening

Malignant mesothelioma (MMe) is a highly aggressive, lethal tumour requiring the development of more effective therapies. The green tea polyphenol epigallocathechin-3-gallate (EGCG) inhibits the growth of many types of cancer cells. We found that EGCG is selectively cytotoxic to MMe cells with respect to normal mesothelial cells. MMe cell viability was inhibited by predominant induction of apoptosis at lower doses and necrosis at higher doses. EGCG elicited H2O2release in cell cultures, and exogenous catalase (CAT) abrogated EGCG-induced cytotoxicity, apoptosis and necrosis. Confocal imaging of fluo 3-loaded, EGCG-exposed MMe cells showed significant [Ca2+]irise, prevented by CAT, dithiothreitol or the T-type Ca2+channel blockers mibefradil and NiCl2. Cell loading with dihydrorhodamine 123 revealed EGCG-induced ROS production, prevented by CAT, mibefradil or the Ca2+chelator BAPTA-AM. Direct exposure of cells to H2O2produced similar effects on Ca2+and ROS, and these effects were prevented by the same inhibitors. Sensitivity of REN cells to EGCG was correlated with higher expression of Cav3.2 T-type Ca2+channels in these cells, compared to normal mesothelium. Also, Cav3.2 siRNA on MMe cells reduced in vitro EGCG cytotoxicity and abated apoptosis and necrosis. Intriguingly, Cav3.2 expression was observed in malignant pleural mesothelioma biopsies from patients, but not in normal pleura. In conclusion, data showed the expression of T-type Ca2+channels in MMe tissue and their role in EGCG selective cytotoxicity to MMe cells, suggesting the possible use of these channels as a novel MMe pharmacological target. \ua9 2012 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd

Regulation of the T-type Ca²⁺ channel Cav3.2 by hydrogen sulfide: Emerging controversies concerning the role of H₂S in nociception

Ion channels represent a large and growing family of target proteins regulated by gasotransmitters such as nitric oxide, carbon monoxide and, as described more recently, hydrogen sulfide. Indeed, many of the biological actions of these gases can be accounted for by their ability to modulate ion channel activity. Here, we report recent evidence that H₂S is a modulator of low voltage-activated T-type Ca²⁺ channels, and discriminates between the different subtypes of T-type Ca²⁺ channel in that it selectively modulates Cav3.2, whilst Cav3.1 and Cav3.3 are unaffected. At high concentrations, H₂S augments Cav3.2 currents, an observation which has led to the suggestion that H₂S exerts its pro-nociceptive effects via this channel, since Cav3.2 plays a central role in sensory nerve excitability. However, at more physiological concentrations, H₂S is seen to inhibit Cav3.2. This inhibitory action requires the presence of the redox-sensitive, extracellular region of the channel which is responsible for tonic metal ion binding and which particularly distinguishes this channel isoform from Cav3.1 and 3.3. Further studies indicate that H₂S may act in a novel manner to alter channel activity by potentiating the zinc sensitivity/affinity of this binding site. This review discusses the different reports of H₂S modulation of T-type Ca²⁺ channels, and how such varying effects may impact on nociception given the role of this channel in sensory activity. This subject remains controversial, and future studies are required before the impact of T-type Ca²⁺ channel modulation by H₂S might be exploited as a novel approach to pain management

Novel anthraquinone based chalcone analogues containing an imine fragment: Synthesis, cytotoxicity and anti-angiogenic activity

A new class of imine derivatives of hybrid chalcone analogues containing anthraquinone scaffold was synthesized and evaluated for their in vitro cytotoxic activity against HeLa, LS174, and A549 cancer cells. The compound 5n with furan ring linked to imino group showed potent activity against all target cells with IC50 values ranging from 1.76 to 6.11 mu M. A mode of action study suggested that compounds induced changes typical for apoptosis in HeLa cells. The most active compounds inhibited tubulogenesis and 5h was found to exhibit a strong anti-angiogenic effect

Novel 1,3,4-thiadiazole-chalcone hybrids containing catechol moiety: synthesis, antioxidant activity, cytotoxicity and DNA interaction studies

Hybrid compounds that combine the 1,3,4-thiadiazole-containing catechol moiety with a chalcone motif were synthesized and examined for their antioxidant activity, cytotoxicity, and DNA-binding activity. A series of thirteen compounds showed strong antioxidant and cytotoxic effects on human acute promyelocytic leukemia HL-60 cells. Several compounds exerted good cytotoxic activities on cervical adenocarcinoma HeLa cells. The treatment of HeLa cells with IC50 and double IC50 concentrations of the compounds 5a, 5c, 5f, and 5m induced a statistically significant increase in the percentage of cells within a subG1 cell cycle phase. The examined compounds caused G2/M cell cycle arrest in HeLa cells. Each of these compounds triggered apoptosis in HeLa cells through activation of caspase-3, the main effector caspase, caspase-8, which is involved in the extrinsic apoptotic pathway, and caspase-9, which is involved in the intrinsic apoptotic pathway. All of the examined compounds decreased the expression levels of MMP2 in HeLa cells and levels of protumorigenic miR-133b. Compounds 5a and 5m lowered the expression level of oncogenic miR-21 in HeLa cells. In addition, compounds 5a, 5f, and 5m decreased the expression levels of oncogenic miR-155 while the treatment of HeLa cells with compounds 5a, 5c, and 5f increased expression of tumor-suppressive miR-206. Observed effects of these compounds on expression levels of four examined miRNAs suggest their prominent cancer-suppressive activity. An investigation by absorption and fluorescence spectroscopy showed more efficient calf thymus DNA binding activity of the compound 5m in comparison to other tested compounds. Results of a pUC19 plasmid cleavage study and comet assay showed DNA damaging activities of compounds 5a and 5c.The peer-reviewed version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3136]Supplementary information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4534