The Role of MR Imaging and MR Angiography in the Evaluation of Patients with Headache

BACKGROUND: Headache is one of the most common complaint in medical practice and the most often neurological symptom. AIM: The aim of our study was to estimate the frequency of abnormal magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) findings in patients with non-acute headache without focal neurological abnormalities. MATERIAL AND METHODS: The results of the MRI and MRA were retrospectively analyzed. As major abnormalities, we took into account tumor, stroke, extraaxial collection, Chiari malformations, and vascular pathology (aneurysm and arterial-venous malformation). RESULTS: Two hundred twenty-five patients fulfilled the criteria. Out of 225 patients with median age of 37 (18–85) years, 78% of the patients were female and 22% were male. In total, we found 8.4% of major abnormalities. On MRI head scan without MRA analysis, we found 50.7% of normal finding, 47.1% of minor abnormalities and 2.2% of major abnormalities. On MRA scan, we found we found 52.9% of normal finding, 40.9% of minor abnormalities, and 6.2% of major abnormalities. CONCLUSION: Our study demonstrates a low but important diagnostic yield of MRI and MRA examination for patients with non-acute headache without focal neurological abnormalities

Teški metali u zemljištu Beograda

The main goal of our work was to determine heavy metal content (Pb, Cd, Zn Cu, Ni, Cr, Hg & As) at different soil depths (5, 10 and 50 cm) in the metropolitan area of Belgrade. The analysis was performed during several years, but our results cover only 2006. Sample selection covered areas near heavy traffic streets and urban parks. Taking in account our results (for the year 2006) and the results acquired from the Public health institute (PHI) of Belgrade (for the years 2003, 2004 and 2005), both obtained by EPA 3050b method, it was quite obvious that our results, that are associated to the depth of 5 cm, have shown that the concentrations of Pb, Zn and Cu are greater then those obtained by PHI. At the same time it could be assumed that the mobility of heavy metals from shallow to deeper depths was limited. The results for Pb (obtained in 2006) and Ni (obtained in 2003, 2005), excide the maximal aloud concentrations (MAC) set by Serbian guideline values for maximal allowed concentrations of dangerous substances in soil and irrigation waters.Usled intenzivnog tehnološkog i industrijskog razvoja u životnu sredinu na razne načine dospevaju velike količine štetnih i toksičnih sup-stanci. Među ovim supstancama značajan je udeo teških metala koji zbog svoje neuništivosti, toksičnosti i biogeohemijskog kruženja predstavljaju veliki problem za životnu sredinu. Industrija, industrijski i komunalni otpad, sagorevanje fosilnih goriva (ugalj, nafta) u industriji, saobraćaju i domaćinstvima najčešći su izvori zagađenja životne sredine teškim metalima i drugim elementima u tragovima. U današnjim uslovima ugroženost zemljišta u Beogradu je velika, a posebna opasnost preti od akcidenata koji se često dešavaju, industrije, saobraćaja, kao i sve većeg broja malih privrednih preduzeća sa značajnom količinom otpada koji predstavlja jedan od glavnih izvora zagađenja zemljišta

Enhanced Pt@Ni catalysts obtained by galvanic displacement method for successful methanol electrooxidation

The successful development of catalysts for the electrooxidation of small organic molecules, such as methanol, requires finding an optimal balance between the catalyst's cost and its activity/stability. Thus far, platinum (Pt) remains one of the best choice for methanol electrooxidation, despite its high costs, limited supply and tendency to poison with carbon monoxide (CO). In this work, the synergistic effect of the supporting material and annealing temperature in different atmospheres on the performance of the Pt@Ni catalyst was examined. The thin film Pt@Ni catalyst was obtained through spontaneous galvanic displacement by placing a drop of hexachloroplatinic acid onto the Ni support. To mitigate platinum susceptibility to poisoning species such as CO and enhance the catalytic efficiency of Pt@Ni at low potentials in methanol oxidation, the as-prepared catalyst was modified using controlled thermal treatment in a reductive atmosphere containing 5 % H2 and in an inert atmosphere (N2). The activity of the catalysts was tested in the methanol oxidation reaction, while the influence of thermal treatment on the surface morphology was monitored using atomic force microscopy (AFM). Preliminary results have indicated that the galvanic displacement method produces ultra-thin film Pt@Ni catalysts, which were further enhanced through controlled thermal treatment. The catalysts annealed in the inert atmosphere demonstrated superior activity compared to the as prepared and catalyst annealed in the reducing atmosphere

Synergistic Effects of the Supporting Material and Annealing Temperature on the Performance of Pt Thin Film Catalysts

The electrocatalytic oxidation of small organic molecules, such as methanol, ethanol and formic acid has been extensively studied due to their properties that make them suitable for use in fuel cells. Particularly, the electrochemical oxidation of formic acid has been comprehensively examined as the anodic reaction in direct formic acid fuel cell. The main goal in the development of the catalysts for formic acid oxidation (FAO) is to find the optimal balance between catalytic performance (activity/stability) and the catalyst cost, i.e. quantity of the noble metal used. In the work presented herein, we explored the synergistic effects of the supporting material and annealing temperature on the performance of Pt thin film catalysts for FAO in acidic media. Our results show that compared to the as-prepared Pt films, the annealed (500 oC) films show exceptional activity for FAO reaction on both Pt/Ni and Pt/Cr catalysts, with 5-fold and 15-fold improvement, respectively. The 500 oC annealed Pt/Cr catalyst was found to be the most active, the most selective and the most stable catalyst in our study. A catalyst with the best marks for all three characteristics is a very rare find in electrocatalysis in general.Lectur

The design of advanced thin-film catalysts for electrooxidation of formic acid

Successful development of catalysts for electrochemical formic acid oxidation (FAO) requires finding an optimal balance between catalytic performance (activity/stability/selectivity) and the catalyst cost. While platinum is one of the most active catalyst materials for FAO, it suffers from performance loss at low overpotentials due to poisoning with CO, which is one of the intermediates formed in the so-called indirect path of FAO. In this work, we explored the synergistic effects of the supporting material and annealing temperature on the performance of Pt thin films over Cr support for FAO in acidic media. In an attempt to reduce the proneness of Pt to poisoning species i.e. CO and improve the catalytic performance of Pt/Cr at low potentials in the formic oxidation reaction, the as-prepared catalyst was modified using controlled thermal treatment. The influence of thermal treatment on the surface morphology was monitored using atomic force microscopy (AFM). The catalyst was electrochemically characterized with cyclic voltammetry and oxidation of CO monolayer, while the performance of the catalyst was tested in formic acid oxidation reaction. Based on the obtained results it was concluded that the improved activity on the annealed Pt/Cr system is a consequence of surface reconstruction of Pt film with predominant (111) orientation. Compared to other facets, the (111) facet selectively favors the oxidation of HCOOH via the direct path, avoiding the formation of COad at low potentials. Moreover, the Pt (111) facets offer improved stability of the catalyst compared to the as-prepared polycrystalline film. Finally, the Cr substrate also experiences improved stability after annealing, presumably due to the formation of a protective oxide layer. Thus, with the successful choice of the supporting material and annealing temperature, we were able to create a thin film catalyst with improved activity, selectivity, and stability, challenging conventional trade-offs in electrocatalysis

Formic Acid Electrooxidation on Cr-Supported Platinum Thin Film Catalyst

In this study, the formic acid electrooxidation reaction was studied on a platinum thin film catalyst obtained by deposition on chromium support (Pt/Cr). In an attempt to reduce the proneness of Pt to poisoning species i.e. CO and improve the catalytic performance of Pt/Cr at low potentials in the formic oxidation reaction, the as- prepared catalyst was modified using controlled thermal treatment. The influence of thermal treatment on the electrode surface morphology was monitored using an atomic force microscope (AFM). Thus obtained catalyst was electrochemically characterized with cyclic voltammetry and oxidation of CO monolayer, while the performance of the catalyst was tested in a formic acid oxidation reaction. The improved activity on annealed Pt/Cr system is a consequence of the surface reconstruction of Pt film with predominant (111) orientation. Compared to other facets, the (111) facet selectively favors direct HCOOH oxidation, avoiding Coad poisoning at low potentials. Moreover, the Pt (111) facets offer improved stability of the catalyst compared to the as-prepared polycrystalline film. Finally, the Cr substrate also experiences improved stability after annealing, presumably due to the formation of a protective oxide layer. Thus, with the successful choice of the supporting material and annealing temperature, we were able to create a thin film catalyst with improved activity, selectivity and stability, in contrast with commonly observed activity-stability tradeoff in catalysis

Oksidativni mehanizmi toksičnosti metala

Mechanisms of metal toxicity have not been fully understood. It was proven in the last decades that certain metals induce increased generation of free radicals, which react lipids, proteins and nucleic acids in the organism inducing tissue-damaging effects and cell death. Metals such as iron copper, chromium, etc. undergo redox cycling and directly catalyze production of free radicals, while mercury, nickel, lead and some others act indirectly by inhibition of antioxidative mechanisims. This paper presents basic understanding of free radicals, their influence on the organism and antioxidative system. Particular attention is given to oxidative mechanisms in which iron, copper, chromium, mercury and lead play role in generation of free radicals and oxidative stress, contrary to zinc which has a significant role in antioxidative cell protection.Mehanizmi toksičnosti metala su još uvek nedovoljno proučeni. Poslednjih decenija dokazano je da određeni metali indukuju i povećanu produkciju slobodnih radikala koji reaguju sa lipidima, proteinima i nukleinskim kiselinama organizma, što rezultira različitim oštećenjima, pa i smrću ćelija. Metali sa promenljivom valencom, kao što su gvožđe, bakar, hrom i dr. direktno katalizuju produkciju slobodnih radikala u reakcijama redoks-ciklusa, dok kadmijum, živa, nikl, olovo i neki drugi metali deluju indirektno tako što inhibiraju antioksidativne mehanizme organizma. U radu su izneta osnovna saznanja o slobodnim radikalima, njihovom dejstvu na organizam i antioksidativnom sistemu organizma. Posebno su obrađeni oksidativni mehanizmi kojima metali gvožđe, bakar, hrom, kadmijum, živa i olovo ostvaruju ulogu u nastanku slobodnih radikala i oksidativnog stresa za razliku od cinka koji ima značajnu ulogu u antioksidativnoj zaštiti ćelija

Teški metali u zemljištu Beograda

The main goal of our work was to determine heavy metal content (Pb, Cd, Zn Cu, Ni, Cr, Hg & As) at different soil depths (5, 10 and 50 cm) in the metropolitan area of Belgrade. The analysis was performed during several years, but our results cover only 2006. Sample selection covered areas near heavy traffic streets and urban parks. Taking in account our results (for the year 2006) and the results acquired from the Public health institute (PHI) of Belgrade (for the years 2003, 2004 and 2005), both obtained by EPA 3050b method, it was quite obvious that our results, that are associated to the depth of 5 cm, have shown that the concentrations of Pb, Zn and Cu are greater then those obtained by PHI. At the same time it could be assumed that the mobility of heavy metals from shallow to deeper depths was limited. The results for Pb (obtained in 2006) and Ni (obtained in 2003, 2005), excide the maximal aloud concentrations (MAC) set by Serbian guideline values for maximal allowed concentrations of dangerous substances in soil and irrigation waters.Usled intenzivnog tehnološkog i industrijskog razvoja u životnu sredinu na razne načine dospevaju velike količine štetnih i toksičnih sup-stanci. Među ovim supstancama značajan je udeo teških metala koji zbog svoje neuništivosti, toksičnosti i biogeohemijskog kruženja predstavljaju veliki problem za životnu sredinu. Industrija, industrijski i komunalni otpad, sagorevanje fosilnih goriva (ugalj, nafta) u industriji, saobraćaju i domaćinstvima najčešći su izvori zagađenja životne sredine teškim metalima i drugim elementima u tragovima. U današnjim uslovima ugroženost zemljišta u Beogradu je velika, a posebna opasnost preti od akcidenata koji se često dešavaju, industrije, saobraćaja, kao i sve većeg broja malih privrednih preduzeća sa značajnom količinom otpada koji predstavlja jedan od glavnih izvora zagađenja zemljišta

Interpolation and Extrapolation of Precipitation Quantities in Serbia

The aim of this paper is to indicate the problems with filling the missing data in precipitation database using interpolation and extrapolation methods. Investigated periods were from 1981 to 2010 for Northern (Autonomous Province of Vojvodina) and Proper Serbia and from 1971 to 2000 for Southern Serbia (Autonomous Province of Kosovo and Metohia). Database included time series from 78 meteorological stations that had less than 20% of missing data. Interpolation was performed if station had missing data for five consecutive months or less. If station had missing data for six consecutive months or more, extrapolation was performed. For every station with mising data correlation with at least three surrounding stations was performed. The lowest acceptable value of correlation coefficient for precipitation was set at 0,30

Interplay between stress and cancer—A focus on inflammation

Stress is an integral part of life. While acute responses to stress are generally regarded as beneficial in dealing with immediate threats, chronic exposure to threatening stimuli exerts deleterious effects and can be either a contributing or an aggravating factor for many chronic diseases including cancer. Chronic psychological stress has been identified as a significant factor contributing to the development and progression of cancer, but the mechanisms that link chronic stress to cancer remain incompletely understood. Psychological stressors initiate multiple physiological responses that result in the activation of the hypothalamic-pituitary-adrenal (HPA) axis, sympathetic nervous system, and the subsequent changes in immune function. Chronic stress exposure disrupts the homeostatic communication between the neuroendocrine and immune systems, shifting immune signaling toward a proinflammatory state. Stress-induced chronic low-grade inflammation and a decline in immune surveillance are both implicated in cancer development and progression. Conversely, tumor-induced inflammatory cytokines, apart from driving a tumor-supportive inflammatory microenvironment, can also exert their biological actions distantly via circulation and therefore adversely affect the stress response. In this minireview, we summarize the current findings on the relationship between stress and cancer, focusing on the role of inflammation in stress-induced neuroendocrine-immune crosstalk. We also discuss the underlying mechanisms and their potential for cancer treatment and prevention