Environmental microbial degradation of xenobiotics

Fizičke i kemijske osobine spojeva, kao i razni činioci iz okoliša, mogu utjecati na razgradljivost spoja. Neke je spojeve moguće razgraditi samo u prisustvu nekog drugog spoja koji služi kao izvor ugljika i energije. Često se spojevi razgrađuju postupno kroz sudjelovanje većeg broja različitih mikroorganizama. Najveći dio biološke razgradnje u prirodi obavljaju mikroorganizmi, najčešće bakterije i neke gljive. Selekcijom mikroorganizama s visokim razgradnim potencijalom te njihovom postupnom prilagodbom na različite prirodno nerazgradljive spojeve dobivene su mikrobne kulture koje se primjenjuju u detoksikaciji otpadnih voda i tla, no o njihovoj širokoj primjeni još ne možemo govoriti. Bolje razumijevanje metaboličkih putova za biodegradaciju pojedinih organskih spojeva, kao i bolje poznavanje mikroorganizama koji razgrađuju organske spojeve omogućit ce svrsishodnu primjenu biodegradacije.Biodegradation of naturally occurring organic compounds follows their synthesis. In contrast, man-made compounds, also known as xenobiotics, are often refractory to degradation. The main reason is that they cannot be recognized by naturally present organisms and therefore do not enter common metabolic pathways. The physical and chemical characteristics of the compounds, as well as environmental factors, may influence their biodegradability. Some compounds may be transformed only in the presence of another compound which appears as a carbon and energy source. Very often compounds are degraded sequentially through the activity of a series of different organisms. The main degraders in nature are microorganisms, mostly bacteria and some fungi. These organisms, due to their rapid rates of multiplication and great metabolic potential, are able to adapt to new substrates. Selection of degradative potent microorganisms and their successive adaptation to a naturally persistent compound might be a powerful means for environmental detoxification. Although numerous laboratory experiments have given positive results, very few are applicable on a large scale. It is necessary to select microorganisms or microbial communities capable of controlled degradation of persistent organic chemicals without their translormation to other, more hazardous compounds. Better understanding of metabolic pathways.for the biodegradation of specific organic compounds as well as more thorough knowledge of degrading microorganisms will make purposeful application of biodegradation possible

Biological effects of uranium

U radu je prikazano djelovanje urana na organizam, pojedine organe ili organske sisteme, stanicu te genetski materijal. Pored visoke toksičnosti, svi su uranovi izotopi radioaktivni, te je i njegov učinak na organizam dvojak: kemijski i aktinički. Nakon apsorpcije uran se prenosi u organizmu u obliku kompleksa s bikarbonatom ili proteinom. Glavno mjesto kemijskog oštećenja je bubreg, dok se netopljivi spojevi mogu odlagati u plućima duže vrijeme gdje će izazvati aktinička oštećenja. U dodiru sa staničnom DNK uran djeluje na genetski materijal uzrokujući ozbiljna oštećenja kromosoma.The effects of uranium on the body, certain organs or organic systems, the cell and genetic material are reviewed. In addition to being highly toxic all uranium isotopes are radioactive and their effect on the body is twofold: chemical and actinic. On absorption uranium is transported in the body in the form of a bicarbonate or a protein complex. The main site of chemical damage is the kidney, whereas non-soluble compounds may be deposited in the lungs where, with time, they are bound to induce actinic impairments. In contact with cellular DNA uranium harms the genetic material by causing serious chromosome damage

Calmodulin levels and the changes in cell physiology

Kalmodulin je modulatorski protein ovisan o kalciju, koji regulira tridesetak enzimskih sustava. Do poremećaja njegove razine u stanici, a i do njegove preraspodjele između citosolne i membranske frakcije dolazi pod utjecajem kemijskih (ioni metala) i bioloških činilaca (hormoni, virusi). Te su pojave osobito izražene pri malignoj transformaciji stanice. Zasebno su obrađena oba razreda činilaca, a ovaj pregled ukratko opisuje i najvažnijc analitičke postupke za određivanje razine kalmodulina u homogenatima tkiva i stanica. Detaljni mehanizam djelovanja kemijskih i bioloških činilaca na razinu kalmodulina još nije poznat.Calmodulin is a calcium-dependent regulator protein which activates about thirty enzymatic systems. Its intracellular levels, as well as the distribution between cytosolic and membrane fractions, are dependent on chemical (metal ions) and biological agents (hormones, viruses). The changes in levels are particularly pronounced after the cell transformation. The influence of transformation and the effect of chemical/biological agents are discussed separately as are the analytical methods for calmodulin determination. A detailed mechanism of action of chemical and biological agents on calmodulin levels is not yet known

Comparison of chromosomal aberrations frequency and polymorphism of GSTs genes in workers occupationally exposed to cytostatics or anaesthetics

Authors compared the incidence of chromosomal aberrations (CAs) of workers occupationally exposed to cytostatics (group EXP1) or anaesthetics (group EXP2) in relationship to polymorphism of GSTM1, GSTP1 and GSTT1 genes. The cytogenetic analysis for chromosomal aberrations frequency and for polymorphisms of genes the PCR and PCR-RFLP method were used. Statistically higher frequency of total CAs was detected in both exposed groups: group EXP1 1.90±1.34%; Mann-Whitney U-test, p=0.001; group EXP2 2.53±1.46%, p=0.0008) as compared to control (1.26±0.93%). In group EXP2 was detected statistically higher frequency of aberrations CSA-type as compared to CTA-type. In xenobiotic metabolizing genes for GST higher frequency of total CAs and constituent types chromatid-type aberrations (CTAs) and chromosome-type aberrations (CSAs) of genes GSTM1 and GSTT1 with null genotype was detected. Statistically significant difference was detected only in CSA-type of aberrations in GSTT1 gene. In gene GSTP1 was not detected any difference in frequency of aberrations in presence of the variant allele. Presented results point out importance of individual susceptibility in evaluation of genotoxic agents of anaesthetics or cytostatics

Procjena cito-/genotoksičnosti irinotekana u V79-stanicama primjenom komet-testa, mikronukleus-testa i testa kromosomskih aberacija

Irinotecan is a topoisomerase I interactive agent, widely used in the treatment of metastatic colorectal cancer. The genotoxic effects of the maximum single dose (18 μg mL-1), recommended monotherapy dose (9 μg mL-1), and recommended combined therapy dose (4.5 μg mL-1) of irinotecan were studied on V79 cells using the comet assay, chromosome aberration assay, and micronucleus test. The cells were treated with irinotecan for 2 h or 24 h. The statistical signifi cance of the results was determined using the one-way ANOVA test and a nonparametric Mann Whitney U test. The comet assay did not show dose-dependent or time-dependent effects. The chromosome aberration analysis showed large DNA rearrangements, i.e., chromosome exchanges. Although the exposed cultures showed a signifi cant increase in micronucleated cells in respect to control, no dose-dependent relation was established among the treated cultures. Timedependent effect was also not observed.Irinotekan je citotoksični lijek koji inhibira enzim DNA-topoizomerazu I. U širokoj je primjeni u terapiji metastatskog karcinoma kolona i rektuma. U uvjetima in vitro primjenom komet-testa, analize kromosomskih aberacija i mikronukleus-testa na V79-stanicama istražili smo genotoksični učinak maksimalne pojedinačne doze (18 μg mL-1), preporučene monoterapijske doze (9 μg mL-1) i preporučene doze irinotekana za kombiniranu terapiju (4,5 μg mL-1). Kulture stanica bile su tretirane irinotekanom 2 h i 24 h. Statistička značajnost određivana je jednosmjernim ANOVA-testom i neparametrijskim Mann Whitneyevim U-testom. Komet-testom nije utvrđen učinak koncentracije i/ili vremena izloženosti. Analiza kromosomskih aberacija pokazala je prisutnost izmjena kromatida, tj. porast broja triradijusa i tetraradijusa. Iako je u kulturama stanica izloženi irinotekanu opažen značajan porast broja mikronukleusa u odnosu na kontrolu, nije uočena ovisnost o dozi lijeka ni o vremenu izloženosti u opisanim eksperimentalnim uvjetima. Dobiveni rezultati upućuju na genotoksičnost irinotekana za V79-stanice. Nijednom od primijenjenih metoda nije utvrđena ovisnost učinka irinotekana o vremenu ili dozi

The biological effects of diagnostic cardiac imaging on chronically exposed physicians: the importance of being non-ionizing

Ultrasounds and ionizing radiation are extensively used for diagnostic applications in the cardiology clinical practice. This paper reviewed the available information on occupational risk of the cardiologists who perform, every day, cardiac imaging procedures. At the moment, there are no consistent evidence that exposure to medical ultrasound is capable of inducing genetic effects, and representing a serious health hazard for clinical staff. In contrast, exposure to ionizing radiation may result in adverse health effect on clinical cardiologists. Although the current risk estimates are clouded by approximations and extrapolations, most data from cytogenetic studies have reported a detrimental effect on somatic DNA of professionally exposed personnel to chronic low doses of ionizing radiation. Since interventional cardiologists and electro-physiologists have the highest radiation exposure among health professionals, a major awareness is crucial for improving occupational protection. Furthermore, the use of a biological dosimeter could be a reliable tool for the risk quantification on an individual basis

Normal and Cut-Off Values of the Cytokinesis-Block Micronucleus Assay on Peripheral Blood Lymphocytes in the Croatian General Population

Mikronukleus (MN) test na limfocitima periferne krvi jedna je od najvažnijih metoda koje se primjenjuju u citogenetičkom nadzoru. Osnovni preduvjet za primjenu nekog testa u svrhu nadzora profesionalno izloženih populacija jest poznavanje normalnih vrijednosti promatranoga biološkog pokazatelja (biomarkera) u kontrolnoj populaciji. Baze podataka na razini opće populacije moraju se redovito obnavljati novim podacima. Cilj ovog istraživanja bio je utvrditi normalne i granične vrijednosti MN-testa na limfocitima periferne krvi 200 zdravih ispitanika obaju spolova iz opće populacije Republike Hrvatske te ispitati koji čimbenici pridonose spontanom nastanku MN. Na razini istražene populacije utvrđeno je prosječno (6,90±3,32) MN (medijan 7 MN), dok je raspon pojedinačnih vrijednosti iznosio 0 do 18 MN u 1000 binuklearnih stanica. Gornja granična vrijednost dobivena izračunavanjem 95. percentila za cjelokupnu promatranu populaciju iznosi 12,5 MN na 1000 limfocita. Utvrđeno je da na spontani nastanak MN utječu spol, dob i navika pušenja. Žene u prosjeku imaju više vrijednosti svih parametara MN-testa od muškaraca, a u njih je bio i naglašeniji porast vrijednosti citogenetičkog nalaza zbog navike pušenja. Kako su literaturni podaci o utjecaju pušenja cigareta na nastanak MN kontradiktorni, planiran je nastavak istraživanja radi razjašnjavanja utjecaja dnevno utrošenog broja cigareta i ukupnog trajanja pušačkog staža na vrijednosti parametara MN-testa. Usporedba rezultata s literaturnim podacima potvrdila je da su dobivene vrijednosti u skladu s vrijednostima MN-testa zabilježenim na općoj populaciji u drugim svjetskim laboratorijima. Normalne i granične vrijednosti MN-testa utvrđene u ovome istraživanju poslužit će kao osnova za usporedbu i tumačenje nalaza MN-testa u ispitanika izloženih populacija te daljnju nadogradnju laboratorijske baze podataka.The cytokinesis-block micronucleus (CBMN) assay on peripheral blood lymphocytes is one of the most important methods employed in cytogenetic biomonitoring. For the purposes of biological dosimetry, it is important to kno the spontaneous frequency of a biomarker and its normal values in general population. These values are used for population databases, which should be updated regularly. In this study, MN levels were investigated in cytokinesis-blocked lymphocytes of 200 healthy male and female blood donors selected at random from the general population of Croatia. The aim was to assess the variability and determine possible infl uences of external and/or internal factors on the background levels of MN and to establish the cut-off value for the CBMN assay. The background frequency of MN was (6.90±3.32) MN (median 7 MN) and the range was 0 to 18 MN per 1000 binuclear lymphocytes. The cut-off value, which corresponds to 95th percentile of the distribution of 200 individual values, was 12.5 MN. Spontaneous formation of MN was infl uenced by sex, age, and smoking. Women had higher MN levels than men. However, only age and smoking signifi cantly increased the values of all parameters evaluated by the CBMN assay. Since the existing literature data on smoking-related formation of MN are contradictory, we will continue these investigations to resolve how the number of cigarettes smoked per day and the duration of smoking in years infl uence the results of the CBMN assay. Our results are consistent with the background MN frequencies reported by other cytogenetic laboratories worldwide. Normal and cut-off values estimated in this study will be used to update the current general population data and as reference for occupationally or accidental exposure

Antineoplastic Drugs as a Potential Risk Factor in Occupational Settings: Mechanisms of Action at the Cell Level, Genotoxic Effects, and Their Detection Using Different Biomarkers

U članku je prikazana osnovna podjela antineoplastičnih lijekova prema mehanizmima djelovanja na razini stanice. Objašnjeni su mehanizmi genotoksičnosti najvažnijih vrsta lijekova koji se primjenjuju u okviru uobičajenih protokola za liječenje zloćudnih novotvorina. Navedena je važeća klasifi kacija antineoplastika prema kancerogenom potencijalu, podaci o mutagenom potencijalu te je prikazana njihova podjela u skladu s anatomsko-terapijsko-kemijskim sustavom klasifi kacije. Sustavno su prikazani najvažniji rezultati svjetskih i hrvatskih istraživanja na populacijama radnika izloženih antineoplasticima, provedenih u razdoblju 1980.-2009. s pomoću četiri najčešće primjenjivane metode: analize izmjena sestrinskih kromatida, analize kromosomskih aberacija, mikronukleus-testa i komet-testa. Objašnjena su osnovna načela navedenih metoda te raspravljene njihove prednosti i nedostaci. Biološki pokazatelji daju važne podatke o individualnoj osjetljivosti profesionalno izloženih ispitanika koji mogu poslužiti unaprjeđenju postojećih uvjeta rada i upravljanju rizicima pri izloženosti genotoksičnim agensima. Na osnovi prednosti i nedostataka citogenetičkih metoda zaključeno je da je mikronukleus-test, koji podjednako uspješno dokazuje klastogene i aneugene učinke, jedna od najboljih metoda dostupnih za otkrivanje štetnih djelovanja antineoplastičnih lijekova koji su u aktivnoj primjeni.This article brings an overview of the mechanisms of action of antineoplastic drugs used in the clinical setting. It also describes the genotoxic potentials of the most important classes of antineoplastic drugs involved in standard chemotherapy protocols. Classifi cation of antineoplastic drugs according to the IARC monographs on the evaluation of carcinogenic risks to humans is accompanied by data on their mutagenicity and the most recent updates in the Anatomical Therapeutic Chemical (ATC) Classifi cation System. We report the main fi ndings of biomonitoring studies that were conducted in exposed healthcare workers all over the world between 1980 and 2009 using four biomarkers: sister chromatid exchanges, chromosome aberrations, micronuclei. and the comet assay. The methods are briefl y explained and their advantages and disadvantages discussed. Biomarkers provide important information on individual genome sensitivity, which eventually might help to improve current working practices and to manage the risks related with exposure to genotoxic agents. Taking into consideration all known advantages and drawbacks of the existing cytogenetic methods, the micronucleus assay, which is able to detect both clastogenic and aneugenic action, is the most suitable biomarker for assessing harmful effects of antineoplastic drugs currently used in health care

Calmodulin levels and the changes in cell physiology

Kalmodulin je modulatorski protein ovisan o kalciju, koji regulira tridesetak enzimskih sustava. Do poremećaja njegove razine u stanici, a i do njegove preraspodjele između citosolne i membranske frakcije dolazi pod utjecajem kemijskih (ioni metala) i bioloških činilaca (hormoni, virusi). Te su pojave osobito izražene pri malignoj transformaciji stanice. Zasebno su obrađena oba razreda činilaca, a ovaj pregled ukratko opisuje i najvažnijc analitičke postupke za određivanje razine kalmodulina u homogenatima tkiva i stanica. Detaljni mehanizam djelovanja kemijskih i bioloških činilaca na razinu kalmodulina još nije poznat.Calmodulin is a calcium-dependent regulator protein which activates about thirty enzymatic systems. Its intracellular levels, as well as the distribution between cytosolic and membrane fractions, are dependent on chemical (metal ions) and biological agents (hormones, viruses). The changes in levels are particularly pronounced after the cell transformation. The influence of transformation and the effect of chemical/biological agents are discussed separately as are the analytical methods for calmodulin determination. A detailed mechanism of action of chemical and biological agents on calmodulin levels is not yet known