Photodynamic cytotoxicity and antibacterial effects of graphene quantum dots in vitro

U ovoj doktorskoj disertaciji ispitivano je fotodinamičko citotoksično dejstvo grafenskih kvantnih tačaka (GKT) na ćelije humanog glioma, kao i njihov antibakterijski efekat na bakterije rezistentne na konvencionalnu antibiotsku terapiju. Iako odlične fotoluminiscentne karakteristike GKT omogućavaju njihovu široku primenu u biomedicini, njihova citotoksičnost, kao i antibakterijsko dejstvo do sada nisu ispitivani. Gliomi su najčešći i najletalniji tumori mozga otporni na konvencionalnu terapiju i često inoperabilni, pa su stoga neophodni novi terapijski pristupi u njihovom lečenju. GKT, ovalne ugljenične dvodimenzionalne nanočestice, sintetisane su elektrohemijskom oksidacijom grafita i karakterisane su metodama UV-Vis spektroskopije, mikroskopijom atomskih sila i transmisionom elektronskom mikroskopijom. Nakon fotoekscitacije plavom svetlošću (470 nm, 1 W) GKT su produkovale reaktivne kiseonične vrste, uključujući i singletni kiseonik (1O2), što je dovelo do oksidativnog stresa i smrti U251 ćelija humanog glioma. Ćelijska smrt indukovana fotoekscitiranim GKT pokazivala je morfološke i biohemijske karakteristike kako apoptoze (eksternalizacija fosfatidil-serina, aktivacija kaspaza, DNK fragmentacija), tako i autofagije (formiranje autofagnih vezikula, konverzija LC3-I u LC3-II, degradacija autofagnog kargo receptora SQSTM1/p62). Genetska inaktivacija ključnog autofagnog proteina LC3B smanjila je fotodinamičku citotoksičnost GKT. Otkrivanje novih, efikasnijih metoda lečenja bakterijskih infekcija postalo je neophodno usled porasta učestalosti infekcija uzrokovanih sojevima bakterija koje pokazuju rezistenciju na veliki broj antibiotika. Iz tih razloga je ispitivan uticaj fotoekscitiranih GKT na Gram-pozitivne i Gram-negativne bakterije, meticilinrezistentni Staphylococcus aureus i Escherichia coli, koje spadaju u grupu najznačajnijih nozokomijalnih patogena, ali se sa velikom učestalošću izoluju i kao izazivači infekcija u vanbolničkoj sredini...In this doctoral dissertation the photodynamic cytotoxic effect of graphene quantum dots (GQD) was investigated in human glioma cells and antibiotic-resistant bacteria. The excellent physicochemical properties of GQD make them suitable candidates for biomedical applications, but their cytotoxicity towards cancer cells or bacteria has not been extensively studied thus far. Gliomas are among the most frequent and letal brain tumors, often inoperable and highly refractive to the standard chemotherapy protocols, thus there is a pressing need for the development of new therapy approaches. GQD, the two-dimensional carbon nanoparticles, were synthesized by the electrochemical oxidation of graphite and characterized by UV-Vis, atomic force microscopy, and transmission electronic microscopy. It was shown that GQD irradiated with the blue light (470 nm, 1 W) produced reactive oxygen species, including singlet oxygen (1O2), which killed U251 human glioma cells by causing oxidative stress. The cell death induced by the photoexcited GQD displayed morphological and/or biochemical characteristics of both apoptosis (phosphatidylserine externalization, caspase activation, DNA fragmentation) and autophagy (formation of autophagic vesicles, LC3-I/LC3-II conversion, degradation of autophagic cargo receptor SQSTM1/p62). Moreover, genetic inactivation of autophagy-essential LC3B protein partly abrogated the photodynamic cytotoxicity of GQD. Searching for new treatments for bacterial infections has become necessary, because of a dramatic increase in the frequency of infections caused by drug-resistant bacteria. Therefore, we examined potential antimicrobial effect of photoexcited GQD on the Gram-positive and Gram-negative bacteria, methicillin-resistant Staphylococcus aureus and Escherichia coli, which are leading nosocomial pathogens..

Investigations of genotoxic potential of levamisole hydrochloride in bone marrow cells of Wistar rats

An experiment was performed under in vivo conditions on bone marrow cells of Wistar rats. The following doses of levamisole hydrochloride were tested: a therapeutic dose of 2.2 mg/kg bm, a dose of 4.4 mg/kg bm, LD50 -25% mg/kg bm, and LD50 -75% mg/kg bm. We followed the effect of levamisole hydrochloride on kinetics of the cell cycle and the appearance of structural and numeric changes in chromosomes in bone marrow cells. The therapeutic dose of levamisole of 2.2 mg/kg bm exhibited a capability to increase mitotic activity in the observed cells, thus confirming knowledge of the immunostimulative effect of this dose of the medicine under in vivo conditions. The other tested doses of levamisole in this experiment, observed in comparison with the control group, had an opposite effect, namely, they caused a reduction in the mitotic activity of bone marrow cells. All the examined doses in vivo exhibited the ability to induce numeric (aneuploid and polyploid) and structural (lesions, breaks and insertions) chromosomal aberrations. It can be concluded on the grounds of these findings that the examined doses have a genotoxic effect

Landscape Planning and Green Infrastructure in Serbia: From National to Belgrade City Planning

The development of landscape planning in Serbia began in the middle of the last century. The principles and objectives of landscape planning were modeled on European trends and developed within the academic framework of the School of landscape architecture at the Faculty of Forestry of the University of Belgrade. The General Plan of Landscapes (1995) was a failed attempt to introduce landscape planning from the framework of academic and scientific debate to institutional spatial planning in Serbia (Vasiljević, 2008). After the ratification of the European Landscape Convention in 2011, a more favorable climate for landscape planning was created in Serbia. As a result of defining a landscape policy, which harmonized the contemporary conceptualization of landscape planning with planning trends in Serbia, ensued the chapter Protection and Arrangement of Landscapes, as part of the Spatial Plan of the Republic of Serbia 2020. For the first time, the spatial concept included all landscapes – urban and rural/ natural, whereas planning principles integrated the principles of landscape ecology (e.g. landscape connectivity) with the principles of aesthetics of landscapes as systems. Landscape character was defined as the target quality and spatial development was supposed to be aligned with it (Vasiljević, 2013). The landscape-ecological approach in the planning of cityscapes, advocated by many authors had little influence on the planning of Belgrade in the past. As the final stage of the project „Green regulations of Belgrade“, the Program for elaboration of the urban plan of the green spaces system of Belgrade is the first bigger shift towards landscape-ecological planning of the City (Cvejić and Teofilović, 2010). The Plan of General Regulation of Green Spaces of the City of Belgrade (2014) was developed as a result of the project in which green infrastructure and its elements were observed through the core, inner and outer ring of the green spaces system. However, this plan has not been adopted yet, and the reason is the insufficiently grounded form of this planning document for which there are no known and well-established planning mechanisms of implementation. In contemporary academic research in Serbia, the concept of green infrastructure is observed through Turner\u27s interpretation of the urban route that is useful from the aspect of environmental quality in a city (Turner, 1995), Ahern’s strategy of landscape planning in which landscapes are designed as green infrastructure (Ahern, 1995), and the spatial planning strategy, which is considered the only way to a certain future of urban landscapes in the light of climate change (Fabos, 2001). The contemporary theoretical approach to planning at the landscape scale was created in such an atmosphere, based on the concept of landscapes as wholes, transdisciplinary approach to research and landscape character as a new value in spatial development planning (Vasiljević, 2012). This theoretical concept is based on unifying the principles of the multifunctionality of landscapes, redundancy and modularity of landscape functions, diversity of landscape structures and connectedness of landscapes at different levels and adaptability of landscapes (Ahern, 2011). Given that the theoretical framework of landscape planning in Serbia is new, as well as its application within the framework of the 2020 SPRS, and that in terms of planning practice in Serbia the understanding of this theoretical concept is in the domain of socialization and cultural reproduction (Vasiljević, 2012 according to Faludi, 2004), it was necessary to find a principle – the idea that local interpretation of theories and their application can be assumed to be consistent with ideas operating at a higher (often national) scale (Allmendinger, 2002). The principle of connectivity, which is materialized through green infrastructure, was considered as a way to implement this theoretical concept at the local level. In order to achieve landscape stability, the principle of connectivity is applied to establish short-term goals, which are seen as long-term adaptation measures to climate change. However, the experience in the implementation of this principle through legal framework points to numerous problems. Although the criteria for establishing green infrastructure are defined through theoretical and strategic research, the existing landscape policies are limited (European Communities, 2008)

PRESENCE OF RESISTANCE IN CAMPYLOBACTER JEJUNI AND CAMPYLOBACTER COLI

There are 18 species belonging to the genus of Campylobacter (rRNK group I), of which thermophilic ones are the following: Campylobacter jejuni, Campylobacter coli, Campylobacter lari and Campylobacter upsaliensis. The aim of our research was to determine the sensitivity of Campylobacter species, isolated from human feces, to antibiotics being used in practice. The study involved 50 human strains of C. jejuni/coli isolated from feces in the Center for Microbiology in the Public Health Institute Nis. Sensitivity was tested by applying the disk diffusion method on seven antibiotics (erythromycin, gentamicin, tetracycline, ciprofloxacin, hloramphenicol, cephalexin and nalidixic acid). Our results showed low resistance to erythromycin, gentamicin and tetracycline (2%), which corresponds to the studies conducted in the world. Moreover, these findings indicate that erythromycin may be considered the drug of choice in the treatment of Campylobacter diarrhea in this region. Resistance to fluoroquinolone and nalidixic acid was 44%, and C. coli showed higher resistance compared to C. jejuni, though statistical significance was not proved

Antimicrobial susceptibility profiles of thermophilic campylobacters isolated from patients in the town of Niš

Background/Aim. In some clinical forms of human Campylobacter infections, such as prolonged diarrhea or associated with postinfections sequels, antibacterial treatment is necessary. The aim of the present study was to evaluate the antimicrobial susceptibility of thermophilic Campylobacter strains isolated from patients with diarrhea, as well as from patients with diarrhea followed by postinfections sequels, to drugs used in the therapy of enterocolitis, and to nalidixic acid used in laboratory identification and differentiation of thermophilic Campylobacter spp. Methods. We studied the antimicrobial susceptibility profiles of 131 Campylobacter strains isolated from patients with diarrhea (122 strains), diarrhea associated with rheumatic disorders (8 strains), and one strain isolated from a patient with Guillain-Barré Syndrome following Campylobacter enterocolitis. Susceptibility testing to erythromycin, gentamicin, tetracycline, chloramphenicol, ciprofloxacin and nalidixic acid was performed by the agar dilution method. Results. In the strains we investigated, resistance to gentamicin and chloramphenicol was not recorded, whereas a low rate of strains resistant to erythromycin (2.4%), a higher prevalence of strains resistant to tetracycline (9.9%), and a high level of resistance to ciprofloxacin (29.8%) and nalidixic acid (33.3%) were registered. All strains resistant to nalidixic acid were also resistant to ciprofloxacin. In addition, there was no difference in the occurrence of resistance between strains isolated from patients with diarrhea as compared to those isolated from patients with diarrhea followed by postinfection disorders. Conclusion. The fact that the most of Campylobacter strains were sensitive to erythromycin and all to gentamicin, makes erythromycin an antibiotic of choice in the treatment of Campylobacter diarrhea and gentamicin when parenteral therapy should be administered. Resistance to tetracycline and, especially, ciprofloxacin, necessitates antibiotic susceptibility testing

Faktori koji utiču na postoperativni mortalitet kod bolesnika sa prelomom kuka

Background/Aim. One of the most significant predictors of mortality after hip fractures is cognitive impairment (dementia). The aim of this study was to report the results of a prospective study of the influence of some factors on sixmonth mortality in elderly patients with hip fractures. Method. The elderly patients with hip fracture were assessed on admission to the hospital using the measures of cognitive function, the mobility before the fracture, and physical comorbidity, the type of fracture and the place of the injury. Six months later, we checked how many of them were still alive. Results. We performed univariate and multivariate analyses in 132 patients and found that the most significant predictors of six-month mortality were dementia, comorbidity, and prefacture mobility. Conclusions. A comprehensive physical and mental health assessment of an elderly patient after hip fracture could predict mortality. A good examination of cognitive functioning could be very useful in choosing the optimal treatment for this type of patients.Uvod/Cilj. U radu su prikazani rezultati prospektivne studije o uticaju nekih faktora na smrtnost starijih bolesnika sa prelomom kuka. Posebno je analiziran uticaj demencije na šestomesečni mortalitet. Metode. Prilikom prijema u bolnicu svakom bolesniku sa prelomom kuka urađena je procena mentalnog statusa (kognicije), procena mobilnosti pre preloma, procena stanja opšteg zdravlja i prisustvo pratećih bolesti, tip preloma, kao i mesto povređivanja. Praćen je šestomesečni mortalitet bolesnika i urađena je univarijantna i multivarijantna regresiona analiza dobijenih rezultata. Rezultati. Obradom podataka kod 132 bolesnika utvrđeni su kao najznačajniji prediktori šestomesečnog mortaliteta: demencija, komorbiditet (prateće bolesti) i mobilnost pre preloma. Zaključak. Celovita procena fizičkog i mentalnog zdravlja je najvažniji činilac u predviđanju ishoda lečenja starih bolesnika sa prelomom kuka. Dobra procena u vezi sa kognitivnim poremećajima, a pre svega demencijom, može biti veoma korisna u odabiru odgovarajućeg načina lečenja bolesnika sa prelomom kuka

Successful isolation of Helicobacter pylori after prolonged incubation: A case report of prolonged incubation for H. pylori

The culture of Helicobacter pylori from a gastric biopsy is the “gold standard” in the diagnosis of H. pylori infection. However, the primary isolation of H. pylori from gastric biopsies is rather demanding. The duration of incubation for the isolation of H. pylori has been recommended to be five to seven days: in the present case, we found that a prolonged incubation period allowed the successful isolation of H. pylori from a patient with ulcus ventriculi. Biopsies were placed directly into transport medium and processed for culture within two hours. On day 14, one suspected H. pylori-like colony appeared on one of the plates. The isolate was confirmed to be H. pylori based on its typical colony morphology, negative Gram stain, and positive urease, catalase and oxidase tests. The isolate, requiring 14 days recovery, later exhibited the normal growth characteristics of H. pylori strains, indicating its unusually long incubation requirement was a temporary predicament

The influence of nutrition and lifestyles on bone health in patients with schizophrenia and depression

© 2020, Serbian Medical Society. All rights reserved. Objective. The aim of this paper is to investigate the influence of nutrition and pattern behaviors on bone health in people with mental health disorders. Methods. A cross-sectional study has been conducted at the Clinic for Psychiatry of the Clinical Center of Kragujevac and at the Department of Neuropsychiatry of the Specialist-Consultative Service of Health Care Center Kragujevac. The survey included 46 patients from the age of 22 to 81, both genders, with schizophrenia as a diagnosis for mental disorders and depression determined by a psychiatrist. Quantitative testing of calcium, magnesium, phosphorus, sodium and potassium has been performed by standard biochemical methods. Vitamin D has been determined by high performance/pressure liquid chromatography i.e. by a liquid chromatography under high pressure. Results. In the whole group of patients tested, 58.7% of patients were physically active and the patients with schizophrenia (p = 0.026) were less physically active. Out of the total number, 67% of patients eat irregularly and this habit is more present in patients with schizophrenia (p = 0.003). In terms of the presence of certain nutrients, fish is more represented in the nutrition of people suffering from depression. Three patients (6.5%) reported osteoporosis in their medical history, one of whom had a spontaneous fracture. In the anamneses (6.5%) of the patients stated that their parents had had spontaneous bone fractures. Low values of 25 (OH) D in the serum were present in both study groups. Conclusion. Unhealthy lifestyles, low level of Vitamin D found in people who have mental health disorders represent risk factors for the reduced bone mass. The results of our research indicate the need for timely identification of potential risk factors and improvement of prevention in order to raise awareness of the importance of healthy lifestyles and behavior modification

The effect of intravitreal administration of bevacizumab on macular edema and visual acuity in age-related macular degeneration with subfoveolar choroidal neovascularisation

Background/Aim. Age-related macular degeneration (AMD) is a leading cause of the loss of central visual acuity in population older than 70 years. We can distinguish wet and dry form of AMD. The aim of the study was to present our early results in treatment of the wet (neovascular) form of AMD with intravitreal administration of bevacizumab. Methods. The study included 39 patients. Each patient underwent a complete ophthalmological examination, fluorescein angiography (FA) and optical coherence tomography (OCT). All the patients received 1.25 mg of intravitreal bevacizumab (0.05 mL of commercial phial of Avastin®). The total of three doses was given with a one-month interval between doses. Results. Among 39 patients, 24 were women and 15 men. The average best corrected visual acuity (BCVA) was improved from 0.09 before the therapy to 0.24 after the administration of all the three doses of bevacizumab (p < 0.001). The average central macular thickness (CMT) measured by OCT was improved from 474 μm in the beginning to 341 μm after the administration of all the three doses of the drug (p < 0.001). There were no side effects. Conclusions. Our short-term experience indicates that intravitreal administration of three doses of bevacizumab in one-month intervals between the doses leads to a significant reduction of macular edema and improvement of BCVA in patients with neovascular AMD

In vivo ispitivanje klastogenog efekta levamizol hidrohlorida na ćelijama kostne srži miševa BALB/c soja

Cytotoxic and genotoxic examinations were performed of the effect of levamisole hydrochloride (2.2 mg/kg bm, 4.4 mg/kg bm, LD50-25% mg/kg bm and LD50-75% mg/kg bm) on bone marrow cells of mice of the BALB/c strain. The effect of levamisole hydrochloride on kinetics of the cellular cycle and the appearance of structural and numerical changes in chromosomes of bone marrow cells were followed. The therapeutic dose of levamisole of 2.2 mg/kg bm showed the ability to increase the mitotic activity of the observed cells, thus confirming knowledge of the immunostimulative effect of this dose of the medicine under in vivo conditions. The other tested doses of levamisole in this experiment, observed in comparison with the control group, had an opposite effect, i.e. they caused a reduction in the mitotic activity of bone marrow cells. All the examined doses in vivo showed the ability of inducing numeric (aneuloid and polyploid) and structural (lesions, breaks and insertions) chromosomal aberrations. On this basis, it can be concluded that the examined doses have a genotoxic effect.Obavljena su citotoksična i genotoksična ispitivanja levamizol hidrohlorida (2.2 mg/kg, t.m., 4,4 mg/kg t.m, LD50-25% mg/kg t.m. i LD50-75% mg/kg t.m) na ćelijama kostne srži miša BALB/c soja. Praćen je uticaj levamizol hidrohlorida na kinetiku ćelijskog ciklusa i pojavu strukturnih i numeričkih promena na hromosomima u ćelijama kostne srži. Terapijska doza levamizola od 2,2 mg/kg t.m. pokazala je sposobnost povećanja mitotske aktivnosti posmatranih ćelija, tako potkrepljujući saznanja o imunostimulativnom efektu ove doze leka u in vivo uslovima. Ostale testirane doze levamizola u ovom eksperimentu, posmatrano u odnosu na kontrolnu grupu, imale su suprotan efekat, tj. uslovile su smanjenje mitotske aktivnosti ćelija kostne srži. Sve ispitivane doze in vivo pokazuju sposobnost indukcije numeričkih (aneuploidije polipleidije) i strukturnih (lezije, prekidi i insercije) aberacija hromosoma. Na osnovu toga može da se zaključi da ispitivane doze imaju genotoksični efekat