Spectroscopis and redox analysis of complex of biliverdin with copper (II) ions

Biliverdin (BV), proizvod katabolizma hem grupe, u interakciji sa prelaznim metalima može da gradi komplekse, ali detalji ovih interakcija u fiziološkim uslovima nisu dovoljno opisani. Ovde su ispitane koordicione/redoks interakcije BV sa jonima Cu(II) u fosfatnom puferu na pH 7,4, koristeći ultraljubičastu-vidljivu spektrofotometriju, masenu spektrometriju, ramansku spektroskopija, metodu nuklearne magnetne rezonacije (NMR), metodu elektronske paramagnetne rezonacije (EPR), fluorimetrijske i elektrohemijske metode. Pokazano je da BV formira stabilan koordinacioni kompleks sa jonima bakra u stehiometriji 1:1. Struktura BV je više planarna i energijski stabilna u kompleksu. Kompleks je pokazao jake paramagnetne efekte koji su pripisani nesparenom delokalizovanom elektronu. Delokalizovani elektron može poticati iz BV ili od jona Cu(II), pa je kompleks sastavljen ili od katjona BV radikala i jona Cu(I) ili od anjona BV radikala i jona Cu(III). Kompleks je podložan oksidaciji samo u prisustvu O2 i višku jona Cu(II), ili jakog oksidacionog sredstva, dok je otporan na redukciona sredstva. Biološki efekti stabilnog metalokompleksa BV koji sadrže delokalizovani nesparni elektron zahtevaju dalje istraživanje. Ovo može dati odgovor na dugogodišnje pitanje razloga ulaganje velike količine energije u katabolizam BV, koji sam po sebi predstavlja relativno bezopasan molekul...Biliverdin (BV) is one of the products of heme catabolism that is known to interact with redox-active metals. (Patho)physiological roles of BV and details of its interactions with metals under physiological conditions, which may be interconnected, are not fully understood. In the current work, we examined coordinate and redox interactions of BV with copper ions (Cu(II)). The interactions were exaimined under conditions that mimic physiological settings - in the phosphate buffer with pH 7.4. A battery of physico-chemical methods were applied, including UV-VIS spectrophotometry, fluorescence spectroscopy, nuclear magnetic resonance spectroscopy (NMR), mass spectrometry, Raman spectroscopy, electron paramagnetic resonance (EPR), and electrochemical methods. BV and copper formed a stable coordination complex with 1 : 1 stoichiometry, with BV showing a more planar structure and energetic stability in the complex. The complex showed strong paramagnetic effects, most likely due to a delocalized unpaired electron. The delocalized e- may come from copper ion or BV. The complex is formally composed of BV radical cation and Cu(I) ion or of BV radical anion and Cu(III) ion. The complex underwent oxidation only in the presence of both O2 and an excess of Cu(II) ion, or a strong oxidizing agent, and it was resistant to reducing agents. The biological effects of the stable BV metallocomplex containing a delocalized unpaired electron should be further examined, and may provide an answer to the long-standing question of high energy investment in the catabolism of BV, which represents a relatively harmless molecule per se..

Effects of Trace Elements on the Fatty Acid Composition in Danubian Fish Species

Anthropogenic pollution poses a major threat to aquatic ecosystems, which can lead to their degradation. The accumulation and toxicity of metals and trace elements in fish leads to physiological and chemical changes in the fish body. In this study, we investigated the effects of bioaccumulation of metals and trace elements on freshwater fish fatty acid profiles at two different sites before and after the discharge of untreated municipal wastewater in two fish species with different diet habits. Although the concentrations of toxic elements were below the maximum levels proposed by the EU and the Republic of Serbia, this study showed statistically significant correlations between the presence of certain elements and the fatty acid (FA) profile in fish muscle. Lower concentrations of polyunsaturated FA in fish sampled after the discharge of untreated municipal wastewater were detected.In this study, the concentrations of metals and trace elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were determined in the muscle tissue of adult roach and white bream at two different sites in the Belgrade section of the Danube. Twenty-six fatty acids, consisting of nine saturated FA (SFAs), seven monosaturated FA (MUFAs) and ten polysaturated FA (PUFAs), were identified. The analysis of the concentration of metals and trace elements of the roach and white bream showed species-specific differences in their bioaccumulation. Four of all elements analyzed (As, Hg, Ni and Pb) correlated significantly with the changes in FA profiles in fish from both sampling sites, with the exception of Cu, which correlated with the FA profile at the site before, and Zn, whose concentration influenced the FA profile at the site after wastewater discharges. The lower PUFA content in the fish from a site under higher environment pressure could indicate that the fish are stressed. The results suggest that changes in lipid composition may be one of the protective mechanisms of cells to cope with anthropogenic stressors

Supplementary data for article: Dimitrijević, M. S.; Bogdanović Pristov, J.; Žižić, M.; Stanković, D. M.; Bajuk-Bogdanović, D.; Stanić, M.; Spasić, S.; Hagen, W.; Spasojević, I. Biliverdin-Copper Complex at Physiological PH. Dalton Transactions 2019, 48 (18), 6061–6070. https://doi.org/10.1039/c8dt04724c

Supplementary material for: [https://pubs.rsc.org/en/content/articlelanding/2019/DT/C8DT04724C#!divAbstract]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3066]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3068

Citoarhitektura humanog paraventrikularnog jedra

Introduction. The significance of this research in terms of structure and biochemical processes in PVN contributes to further understanding of vital physiological processes from delivery and stress to delicate chemical processes that keep the hypothalamo-hypophysial axis in balance. Conclusion. Comparative studies of the human hypothalamus with the hypothalamus of other mammals enable further research, especially pharmacological and physiological ones. These are made possible with the aid of highly sophisticated equipment for examination of neurophysiological features of the brain.Ovim člankom smo želeli da ukažemo na važnost paraventrikularnog jedra pokazujući novije podele ćelijskih podgrupa, kao i podele prema hemijskom sastavu proteina koji se nalaze u njemu. Fiziološka uloga hipotalamo-hipofiznog kompleksa je svakako uslovljena njegovim vezama sa drugim delovima mozga, kao i hemijskim supstancijama od kojih zavisi prenos signala. Uvođenjem savršenijih tehnika u razvojno-neurobiološka istraživanja, možemo da pratimo i poredimo mnoge delove mozga, pa i paraventrikularno jedro s istim jedrima drugih sisara, a time omogućimo lakši rad na eksperimentalnim modelima fiziološko-farmakoloških i drugih istraživanja

Supplementary data for article: Dimitrijević, M. S.; Bogdanović Pristov, J.; Žižić, M.; Stanković, D. M.; Bajuk-Bogdanović, D.; Stanić, M.; Spasić, S.; Hagen, W.; Spasojević, I. Biliverdin-Copper Complex at Physiological PH. Dalton Transactions 2019, 48 (18), 6061–6070. https://doi.org/10.1039/c8dt04724c

Supplementary material for: [https://pubs.rsc.org/en/content/articlelanding/2019/DT/C8DT04724C#!divAbstract]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3066]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3068

Ground red hot pepper agar in the isolation and presumptive identification of Cryptococcus neoformans

The study compared ground red hot pepper agar (GRHP) and Guzzotia abyssinica creatinine agar (GACA), a medium routinely used for isolation of Cryptococcus neoformans. In order to confirm the capacity of GRHP to support the Cr. neoformans growth and pigment production, 15 strains were inoculated onto GRHP and GACA. No significant differences in the growth and pigmentation of the tested strains on the two media were noted. As heavily contaminated specimens, 50 samples of pigeon droppings were examined by plating on GRHP and GACA, which resulted in the isolation of 14 and nine Cr. neoformans strains, respectively. The results indicate that GRHP, as a result of its superior selectivity and significant reduction of contaminant growth, provides better conditions than GACA for isolation and presumptive identification of Cr. neoformans from heavily contaminated specimens

Staphylococcus sciuri as a part of skin, nasal and oral flora in healthy dogs

The coagulase -negative species Staphylococcus sciuri is widespread in nature and is associated with a variety of domestic and wild animals. However, the occurrence of S. sciuri in dogs has received little attention so far. In the present study, we established the prevalence of S. sciuri in a large population of healthy dogs, and characterized isolated strains. Samples from two mucous membrane sites (anterior nares and mouth), and two hair-coated sites (head and withers) were taken from 122 dogs and inoculated into STS agar, a novel selective medium that was introduced and tested in the study. In total, 116 isolates of S. sciuri were obtained from 488 specimens. S. sciuri was isolated from 56 out of 122 (46%) dogs. The occurrence of S. sciuri in the anterior nares and mouth were significantly higher than those in withers and head. No significant association of S. sciuri occurrence in dogs and factors such as sex, age, and living environment (indoor/outdoor) was found. Out of 56 dogs, which tested positive for S. sciuri, 30 (54%) would have it as a resident flora. Thus, we showed that S. sciuri was frequently present as a part of skin, nasal and oral flora in healthy dogs both as a resident and transient carriage

Prognostic significance of epigenetic inactivation of p16, p15, MGMT and DAPK genes in follicular lymphoma

In this study, methylation-specific polymerase chain reaction was used to investigate the role and potential prognostic significance of the methylation status of p16, p15, MGMT and DAPK genes in 32 specimens of follicular lymphoma (FL). Hypermethylation of p15 gene was associated with lower hemoglobin level (P = 0.020) and MGMT/DAPK comethylation with relapsed disease (P = 0.018). Among all patients with FL, there was no significant difference in the overall survival between those with hypermethylated and unmethylated of any examined genes. Therefore, we analyzed methylation in the different groups according to FL International Prognostic Index (FLIPI) and tumor grade. In the high-risk group, patients with hypermethylated p16 gene had significant lower overall survival than those with unmethylated p16 (P = 0.006) and trend toward shorter failure-free survival (P = 0.068). In the same risk group, there was a trend toward longer overall survival for patients with hypermethylated MGMT gene, compared to those with unmethylated MGMT gene (P = 0.066). p15 methylation had impact on shorter overall survival in grade I group of patients (P = 0.013), and DAPK methylation tended to have impact on shorter failure-free survival in the whole examined group (P = 0.079). Our results suggest that promotermethylation of p16 and MGMT genes could have prognostic value when used in combination with the FLIPI and p15 methylation in combination with tumor grade. Concurrent methylation of MGMT and DAPK genes could be the marker of tumor chemoresistance and disease recurrence

p14(ARF) methylation is a common event in the pathogenesis and progression of myxoid and pleomorphic liposarcoma

Liposarcoma represents the most frequent group of soft tissue sarcomas. The group can be divided into three different classes: (1) differentiated/undifferentiated (WDLPS/DDLPS), (2) myxoid/round cell (MLPS/RCLPS) and (3) pleomorphic liposarcoma (PLS). It has become apparent that p53-p14 and Rb-p16 pathways play important roles in the pathogenesis of various sarcoma types. Molecular studies of the genes involved in these two pathways showed wide variations between the liposarcoma subtypes or even within the same subtype. We sought to examine mutational status of p53 and methylation status of p16(INK4a)/p14(ARF) genes in primary and recurrent liposarcoma tumors. There were twelve myxoid (12/18, 66.7 %) and six pleomorphic liposarcoma (6/18, 33.3 %) samples. Immunohistochemical analysis revealed that p53 protein was overexpressed in 3/12 MLPS (25 %) and 6/6 PLS (100 %). Mutational analysis showed that 2/11 MLPS (18.2 %) and 2/6 PLS (33.3 %) contained mutated p53 gene. On the other hand, 3/18 samples (16.7 %) had methylated p16 promoter. However, the frequencies of the p14(ARF) gene methylation were 83.3 % (10/12) and 50 % (3/6) in myxoid and pleomorphic group, respectively. Overall, 15 out of 18 (83.3 %) samples had either p53 gene mutation or methylated p14(ARF) promoter. The results from the current study suggest significant impact of the p14(ARF) gene methylation on the pathogenesis and progression of myxoid and to a lesser extent pleomorphic liposarcoma. Despite the limited number of samples, our study points to necessity of further investigation of p53-p14 and Rb-p16 pathways in liposarcoma

The formation of Fe3+-doxycycline complex is pH dependent: implications to doxycycline bioavailability

The interactions of drugs with iron are of interest in relation to the potential effects of iron-rich foods and iron supplements on sorption and bioavailability. Doxycycline (DOX), a member of the tetracycline class of broad-spectrum antibiotics, is frequently administered by oral route. In the digestive tract, DOX can be exposed to iron at different pH values (stomach pH 1.5–4, duodenum pH 5–6, distal jejunum and ileum pH 7–8). In relation to this, we analyzed the impact of pH on Fe3+-DOX complex formation. The optimal conditions for Fe3+-DOX complex formation are pH = 4 and [Fe3+]/[DOX] = 6 molar ratio. HESI-MS showed that Fe3+-DOX complex has 1:1 stoichiometry. Raman spectra of Fe3+-DOX complex indicate the presence of two Fe3+-binding sites in DOX structure: tricarbonylamide group of ring A and phenolic-diketone oxygens of BCD rings. The Fe3+-DOX complex formed at pH = 4 is less susceptible to oxidation than DOX at this pH. The increase of pH induces the decomposition of Fe3+-DOX complex without oxidative degradation of DOX. The pH dependence of Fe3+-DOX complex formation may promote unwanted effects of DOX, impeding the absorption that mainly takes place in duodenum. This could further result in higher concentrations in the digestive tract and to pronounced impact on gut microbiota.This is the peer-reviewed version of the article: Korać Jačić J, Dimitrijević MS, Bajuk-Bogdanović DV, Stanković DM, Savić SD, Spasojević IB, MIlenković MR. The formation of Fe3+-doxycycline complex is pH dependent: implications to doxycycline bioavailability. in Journal of Biological Inorganic Chemistry. 2023;28:679-687. doi: [10.1007/s00775-023-02018-w]