Biljana Markovic

Modification of Structural and Luminescence Properties of Graphene Quantum Dots by Gamma Irradiation and Their Application in a Photodynamic Therapy

Herein, the ability of gamma irradiation to enhance the photoluminescence properties of graphene quantum dots (GQDs) was investigated. Different doses of γ-irradiation were used on GQDs to examine the way in which their structure and optical properties can be affected. The photoluminescence quantum yield was increased six times for the GQDs irradiated with high doses compared to the nonirradiated material. Both photoluminescence lifetime and values of optical band gap were increased with the dose of applied gamma irradiation. In addition, the exploitation of the gamma-irradiated GQDs as photosensitizers was examined by monitoring the production of singlet oxygen under UV illumination. The main outcome was that the GQDs irradiated at lower doses act as better photoproducers than the ones irradiated at higher doses. These results corroborate that the structural changes caused by gamma irradiation have a direct impact on GQD ability to produce singlet oxygen and their photostability under prolonged UV illumination. This makes low-dose irradiated GQDs promising candidates for photodynamic therapy.

Embolization with absolute ethanol injection of insufficiently ligated renal artery after open nephrectomy

A 54-year-old woman was admitted to hospital for hypotension and anemia which was due to intermittent hemorrhage from a lumbar drain. She had undergone open nephrectomy ten days earlier in another hospital for the right dysfunctional kidney with staghorn calculi. Ultrasound in our hospital showed a right retroperitoneal hematoma. Surgical exploration was performed twice whereby the hematoma was partially eliminated; however, the point of bleeding was not identified. Repeated attacks of bleeding from the drain accompanied by acute pain made the hypotension with tachycardia even worse, which led to a life-threatening hemorrhagic shock. Extravasation from the insufficiently ligated right renal artery was then shown on computed tomography aortography. After selective catheterization of this arterial stump with a mixture of alcohol and contrast media, complete occlusion of the remaining part of the resected renal artery was achieved. Application of absolute alcohol, though risky, proved to be a quick and efficient alternative method of occlusion of the bleeding renal arterial stump.

Antibacterial potential of electrochemically exfoliated graphene sheets

Electrochemically exfoliated graphene is functionalized graphene with potential application in biomedicine. Two most relevant biological features of this material are its electrical conductivity and excellent water dispersibility. In this study we have tried to establish the correlation between graphene structure and its antibacterial properties. The exfoliation process was performed in a two electrode-highly oriented pyrolytic graphite electrochemical cell. Solution of ammonium persulfate was used as an electrolyte. Exfoliated graphene sheets were dispersed in aqueous media and characterized by atomic force microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X photoelectron spectroscopy, X-ray diffraction, electron paramagnetic resonance, zeta potential, contact angle measurements and surface energy. Antibacterial assays have shown lack of the significant antibacterial activity. Major effect on bacteria was slight change of bacteria morphology. Membrane remained intact despite significant change of chemical content of membrane components.

Resolving Erythrocytosis and Hypertension after Open Surgical Extirpation of Giant Renal Cyst Measuring 30 cm: Case Report

The case of giant renal cyst measuring 30 cm, accompanied by abdominal swelling and erythrocytosis, is presented. A 45-year-old male presented with large abdominal mass, atrophic left kidney, hypertension, and erythrocytosis. The patient underwent multiple preoperative phlebotomies, open extirpation of the cyst, and nephrectomy. After the surgery, erythrocytosis ceased completely, blood pressure became normal without any medications whereas function of the remaining kidney was stable. The giant renal cysts measuring more than 15 cm are extremely rare. However, they can cause erythrocytosis and hypertension very frequently, especially in the case of cysts originating from the proximal tubule. To our knowledge, this is the largest renal cyst published in the literature that caused the above-mentioned complications.

Lack of clastogenic effects of L-thyroxine in whole-blood cultured human lymphocytes

Abstract Thyroidhormonesstimulateaerobicmetabolismwhichmayleadtooxidativestressaccompaniedbydamagetovari-ous cellular macromolecules, including DNA. Previous comet assay studies have shown that thyroid hormonescause DNA damage due to the creation of reactive oxygen species (ROS). However, cytogenetic studies have beenequivocal because although an increase in the sister-chromatid exchange frequency per cell has been reported in-creasedmicronucleifrequencyhasnot.Weusedcytogeneticexaminationofchromosomebreakageandaberrationsinwhole-bloodculturesofhumanperipheralbloodlymphocytestoinvestigatepossibleclastogeniceffectswhenlym-phocytes were exposed to 0.002 μMto50μM of L-thyroxine for 24 h and 48 h, these concentrations being chosenbecausetheyhadbeenusedinpreviousstudiesofsister-chromatidexchangeandmicronucleifrequency.Underourexperimental conditions thyroxine did not induced any statistically significant increase in chromosome breakage oraberrations. This lack of clastogenic effects is in contrast to the reported comet assay results obtained using purifiedlymphocytes, possibly because whole-blood cultures contain catalase and glutathione peroxidase capable of reduc-ing the effects of reactive oxygen species.

Photo-induced antibacterial activity of four graphene based nanomaterials on a wide range of bacteria

Due to controversial reports concerning antibacterial activity of different graphene based materials it is very important to investigate their antibacterial action on a wide range of Gram-positive and Gram-negative bacteria. In this paper we have investigated the structure induced phototoxic antibacterial activity of four types of graphene based materials: graphene oxide (GO), graphene quantum dots (GQDs), carbon quantum dots (CQDs) and nitrogen doped carbon quantum dots (N-CQDs). Antibacterial activity was tested on 19 types of bacteria. It is found that nanometer-size CQDs and N-CQDs are the most potent agents whereas micrometer-size GO has very poor antibacterial activity. Electron paramagnetic resonance measurements confirmed photodynamic production of singlet oxygen for all types of used quantum dots. Detailed analysis has shown that N-CQDs are an excellent photodynamic antibacterial agent for treatment of bacterial infections induced by Enterobacter aerogenes (E. aerogenes), Proteus mirabilis (P. mirabilis), Staphylococcus saprophyticus (S. saprophyticus), Listeria monocytogenes (L. monocytogenes), Salmonella typhimurium (S. typhimurium) and Klebsiella pneumoniae.

Repeated endoscopic treatments of multiple recurrent ureteral tumors following 15-year-long history of bladder tumors in the patient from endemic nephropathy region

Ureteral urothelial tumors (UUT) are uncommon; their incidence is higher in areas affected by Balkan endemic nephropathy (BEN), with low–grade lesions prevalent. In these patients, the efficacy of conservative surgery is comparable to that of nephroureterectomy. Endoscopic treatment is indicated for single, small and low grade UUT, in older patients with significant comorbidity. The case of an 84–year–old lady from an area affected by BEN is presented. Over 20 years, the patient underwent five endoscopic interventions for multiple UUT, and numerous endoscopic interventions for recurrent bladder tumors. Among a highly select group of patients, endoscopic treatment of multiple small superficial low–grade ureteral tumors may prove successful.

The remnant of a congenital, blind- ended megaureter in a 23-year-old woman causing chronic pain and urinary infections

Multicystic dysplastic kidney (MCDK) is a congenital anomaly as the result of abnormal interaction between the ureteric bud and metanephric mesenchyme. Unilateral MCDK can be associated with other anomalies of the genitourinary tract. Relatively rare associated anomaly is the presence of ipsilateral refluxing blind megaureter. The patient reported herein is a 23–years–old woman with involuted MCDK and ipsilateral blind megaureter causing chronic urinary infection and chronic abdominal pain. Preoperative and intraoperative examination failed to detect the communication between megaureter and the urinary bladder.