Ana Budimir

Metal ions, Alzheimer's disease and chelation therapy

Metal ions, Alzheimers disease and chelation therapy In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases. Kovinski ioni, Alzheimerova bolest i kelacijska terapija Najnovija istraživanja na polju neurodegeneracije jasno pokazuju da kovinski ioni imaju značajnu ulogu u patogenezi Alzheimerove kao i drugih neurodegenerativnih bolesti. U skladu s ovim spoznajama upotreba kovinskih kelatora predstavlja zanimljiv i inovativan farmakološki pristup daljnjem istraživanju i mogućoj terapiji neurodegenerativnih stanja. U ovom radu ukratko je dan sažetak istraživanja upotrebe kovinskih kelatora u tretmanu Alzheimerove bolesti s posebnim osvrtom na istraživanja analoga 8-hidroksikinolina.

Hydroxyquinoline based binders: Promising ligands for chelatotherapy?

We report here a thorough physico-chemical study of the coordination properties of clioquinol, an oxine-type active neurological drug in Alzheimers disease, toward biologically relevant divalent metal ions (Cu, Zn, Ni, Co and Mn). Using a fruitful combination of electrospray mass spectrometry, absorption spectrophotometry and potentiometry, we have characterized the mono- and bis-chelated metal ion species. The determination of the stability constants showed a classical thermodynamic behavior along the studied series with the cupric complexes being by far the most stable species. Our data are discussed within the scope of Alzheimers disease.

NDM-1-producing Klebsiella pneumoniae, Croatia.

To the Editor: The novel metallo-β-lactamase named New Delhi metallo-β-lactamase (NDM-1) was identified from Klebsiella pneumoniae and Escherichia coli isolates in Sweden from a patient previously hospitalized in India (1). NDM-1 is spreading rapidly worldwide to nonclonally related isolates, many of which are directly or indirectly tracked to the Indian subcontinent (2). A carbapenem-resistant K. pneumoniae strain, KLZA, was isolated in May 2009 from the culture of a blood sample from of a 40-year-old man on the day after his admission to a surgical intensive care unit of the Clinical Hospital Center in Zagreb, Croatia. The patient had been transferred after 5 days of hospitalization in Bosnia and Herzegovina following a car accident. The clinical history mentioned antimicrobial drug treatment that did not include carbapenems (gentamicin, metronidazole, and ceftriaxone) and no link to the Indian subcontinent. Antimicrobial drug susceptibility testing was performed by Vitek2 (bioMerieux, Marcy-l’Etoile, France) and broth microdilution and interpreted according to the latest documents from the European Committee on Antimicrobial Susceptibility Testing (www.eucast.org/clinical_breakpoints/, version 1.1). The strain proved resistant to imipenem and meropenem, to all broad-spectrum cephalosporins, and to aminoglycosides and susceptible to ciprofloxacin and tigecycline (Table). We checked for blaVIM, blaIMP, blaSPM, blaGIM, blaSIM, and blaNDM resistance genes by using PCR. A PCR product was obtained only with the NDM primers, after being purified (QIAquick PCR Purification Kit, QIAGEN, Hilden, Germany), its sequence showed 100% identity with blaNDM-1. Table MIC of the KLZA strain of Klebsiella pneumoniae and its transconjugant and recipient Strain genotyping was performed by multilocus sequence typing to determine the sequence type (ST) of the isolate and to establish a comparison with previously reported NDM-1–producing isolates. Allelic numbers were obtained on the basis of sequences of 7 housekeeping genes at www.pasteur.fr/recherche/genopole/PF8/mlst/Kpneumoniae.html. Multilocus sequence typing identified K. pneumoniae KLZA as an ST25 strain, which significantly differs from the ST14 type found in the index NDM-1–producing strain and from other isolates originating from India (1) and then in other countries. ST25 K. pneumoniae was also found in K. pneumoniae isolates in Geneva (3). Other K. pneumoniae STs harboring NDM-1 were ST15, ST16, and ST147 (4–7). Resistance was transferred by conjugation to E. coli J53, with selection based on growth on agar in the presence of ceftazidime (10 mg/L) and azide (100 mg/L). The conjugant T1 showed resistance to β-lactams, including all carbapenems, as well as decreased susceptibility to ciprofloxacin. The KLZA strain and its transconjugant harbored other determinant of resistance, namely blaCTX-M-15, blaCMY-16, and qnrA6. Plasmid incompatibility groups, determined by a PCR-based replicon typing method, belonged to the incA/C replicon type. This report of an NDM-1–producing K. pneumoniae in Croatia adds to those of other cases in patients from patients hospitalized in the Balkan area. The patient in this report had no apparent link to the Indian subcontinent. In a survey conducted by the European Centre for Disease Prevention and Control to gather information about the spread of NDM-1–producing Enterobacteriaceae in Europe and reporting cases from 13 countries during 2008–2010, five of the 55 persons with known travel histories had traveled to the Balkan region during the month before diagnosis of their infection: 2 to Kosovo and 1 each to Serbia, Montenegro, and Bosnia and Herzegovina. All had received hospital care in Balkan countries because of an illness or accident that occurred during the journey (7). Two of the latter cases (4,8) and a case from Germany (9) were subsequently published. No patient had any apparent link to the Indian subcontinent. Although the way NDM-1 isolates might have been imported to western Europe not only from the Indian subcontinent but also from Balkan countries (10) has been highlighted, awareness of western Europe as a possible area of endemicity remains limited. The aforementioned report from Germany, although recognizing that the patient had been repatriated after hospitalization in Serbia, declared “no evidence about contact with people from regions where NDM-enterobacteria are endemic” (9). This limited awareness shows the threat of neglecting to screen patients who are transferred from countries thought not to be at risk for NDM-1. Furthermore, it means that specimen are not sent to the local reference laboratories and recognized as positive for NDM-1, thus permitting wide dissemination of NDM-1–producing enterobacteria in the community (4). The accumulating evidence of NDM-1 from the Balkan area could suggest a possible multifocal spread of this enzyme, with the Balkans as a possible second area of endemicity, in addition to the Indian subcontinent, and prompts for widespread epidemiologic surveillance.

A variant of the Southern German clone of methicillin-resistant Staphylococcus aureus is predominant in Croatia

The aim of the present study was to investigate the antibiotic susceptibility patterns and molecular epidemiology of clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered in 24 hospitals in 20 cities in Croatia from October to December 2004. A total of 1815 consecutive S. aureus isolates were recovered, 248 of which were MRSA. The MRSA isolates were analysed using spa typing, multilocus sequence typing and SCCmec typing. Furthermore, the presence of Panton-Valentine leukocidin (PVL) genes was determined as a genetic marker for community-associated MRSA. The MRSA prevalence was 14%. Ninety-six per cent of the MRSA isolates were resistant to ciprofloxacin, 95% to clindamycin and azithromycin, 94% to gentamicin, and 93% to erythromycin. The majority of the MRSA isolates (78%) was associated with the ST111-MRSA-I clone. In addition, various other endemic MRSA clones were observed, such as the ST247-MRSA-I (4%), the ST45-MRSA-IV (2%), the ST5-MRSA-I (2%), the ST239-MRSA-III (2%), the ST5-MRSA-II (1%), the ST8-MRSA-IV (1%) and the ST5-MRSA-IV (<1%) clones. Furthermore, we observed one PVL-negative ST80-MRSA-IV isolate. Four PVL-positive MRSA isolates were found, associated with ST8-MRSA-IV, ST80-MRSA-IV and ST80-MRSA-I. The ST111-MRSA-I clone was predominant in Croatia. Future surveillance studies of MRSA are important to elucidate whether changes in the clonal distribution of MRSA will occur, and if the minor endemic MRSA clones observed in the present study will replace the ST111-MRSA-I clone on a large scale.

Cotton textiles modified with citric acid as efficient anti-bacterial agent for prevention of nosocomial infections

Aim To study the antimicrobial activity of citric acid (CA) and sodium hypophosphite monohydrate (SHP) against gram-positive and gram-negative bacteria, and to determine the influence of conventional and microwave thermal treatments on the effectiveness of antimicrobial treatment of cotton textiles. Method Textile material was impregnated with CA and SHP solution and thermally treated by either conventional or microwave drying/curing treatment. Antibacterial effectiveness was tested according to the ISO 20743:2009 standard, using absorption method. The surfaces were morphologically observed by scanning electron microscopy, while physical characteristics were determined by wrinkle recovery angles method (DIN 53 891), tensile strength (DIN 53 837), and whiteness degree method (AATCC 110-2000). Results Cotton fabric treated with CA and SHP showed significant antibacterial activity against MRSA (6.38 log10 treated by conventional drying and 6.46 log10 treated by microwave drying before washing, and 6.90 log10 and 7.86 log10, respectively, after 1 cycle of home domestic laundering washing [HDLW]). Antibacterial activity was also remarkable against S. aureus (4.25 log10 by conventional drying, 4.58 log10 by microwave drying) and against P. aeruginosa (1.93 log10 by conventional and 4.66 log10 by microwave drying). Antibacterial activity against P. aeruginosa was higher in samples subjected to microwave drying/curing than in those subjected to conventional drying/curing. As expected, antibacterial activity was reduced after 10 HDLW cycles but the compound was still effective. The surface of the untreated cotton polymer was smooth, while minor erosion stripes appeared on the surfaces treated with antimicrobial agent, and long and deep stripes were found on the surface of the washed sample. Conclusion CA can be used both for the disposable (non-durable) materials (gowns, masks, and cuffs for blood pressure measurement) and the materials that require durability to laundering. The current protocols and initiatives in infection control could be improved by the use of antimicrobial agents applied on cotton carbohydrate polymer.

The effectiveness of systemic eradication therapy against oral Helicobacter pylori

BACKGROUND Helicobacter pylori infection is associated with numerous gastroduodenal diseases. The oral cavity could be a potential extragastric reservoir for H. pylori, and oral H. pylori might cause gastric reinfection after the eradication therapy. The aim of the study was to evaluate the presence of H. pylori in oral cavity of patients with gastric H. pylori infection and to examine the effectiveness of the eradication therapy against H. pylori in stomach and in the oral cavity. METHODS Fifty-six patients with chronic periodontitis and gastric H. pylori were enrolled in the study. Gastric H. pylori infection was determined using (13) C-urea breath test before and 3 months after eradication therapy. The presence of the oral H. pylori was assessed using polymerase chain reaction before and 3 months after eradication therapy. The 1-week eradication therapy consisted of amoxycilin 1 g, clarithromycin 500 mg, and proton pump inhibitor 20 mg twice a day. RESULTS Of 56 subjects with gastric infection, 23 (41.1%) harbored H. pylori in the oral cavity. Eradication rate in stomach was 78.3%, whereas in the oral cavity, H. pylori was not detected from any sample after the eradication therapy. CONCLUSION Almost half of the patients with gastric H. pylori harbored the bacterium in the oral cavity. After the eradication therapy, H. pylori was not detected in the oral cavity, what suggests high effectiveness of the therapy protocol in the oral cavity, or it is possible that oral H. pylori is of a transient character.

Clonal spread of carbapenem-resistant OXA-72-positive Acinetobacter baumannii in a Croatian university hospital

BACKGROUND From July to October 2008, 34 Acinetobacter baumannii isolates were involved in an outbreak at the Clinical Hospital Center, Zagreb. The aim of this study was to characterize the mechanisms of carbapenem resistance in our A. baumannii isolates and determine their epidemiology. METHODS Antibiotic susceptibilities were determined by broth microdilution. PCR was used to detect the presence of carbapenemases. Genotyping of the isolates was performed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and repetitive sequence-based PCR (rep-PCR). RESULTS Thirty-three carbapenem-resistant isolates were positive for the acquired bla(OXA-72) and one unrelated isolate was positive for bla(OXA-58). The bla(OXA-72)-positive isolates were shown to be clonally related by RAPD, rep-PCR, and PFGE. CONCLUSIONS On the basis of susceptibility testing, β-lactamase characterization, and genotyping of the isolates we can conclude that clonal spread of endemic isolates was responsible for the high frequency of OXA-72-positive multidrug-resistant A. baumannii in this setting. Most of the isolates originated from the intensive care unit indicating local dissemination within the hospital and pointing to the potential source of isolates.

Study of antimicrobial properties of cotton medical textiles treated with citric acid and dried/cured by microwaves

The purpose of this study was to examine antibacterial and antifungal activity of antibacterial finish based on Citric acid on cotton medical textiles. The ability to effectively reduce the number of gram-negative, gram-positive bacteria and yeast was evaluated, specifically comparing the antibacterial activity after two different drying/curing methods. Citric acid (CA) and diethyl–tetradecyl–[3–(trimethoxysilyl)-propyl] ammonium chloride (Quat) were used for hygiene and disinfection purposes of medical textiles in this study. It was applied by pad-dry process and its fixation to cellulose hydroxyls was enhanced either by high curing temperatures or microwaves (MW). Determination of antibacterial activity of finished products was performed according to ISO 20743:2007 standard before the washing and after the 10 washing cycles. Antibacterial activity was tested against gram-negative bacteria, Escherichia coli, gram-positive-Staphylococcus aureus and yeast, Candida albicans. Obtained results are confirming the possibility of eco-friendly CA application, for the purpose of antimicrobial finishing of cotton medical textiles. Prevention of nosocomial infections with the Citric acid is possible using both curing methods (convection and microwave) and furthermore, the treatment is durable up to 10 washing cycles. Citric acid, as one of the suitable active substances is crosslinked to the cellulose hydroxyls by the formation of ester linkages. Its antimicrobial effectiveness against the chosen microorganisms proved to be the best against S. aureus. Applied finish bath has additional crease proof effectiveness providing sufficient both antimicrobial and crease proof effectiveness, so as the durability against 10 washing cycles.

Acid–base and electrochemical properties of manganese meso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria

The difference in electrostatics and reduction potentials between manganese ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP) and manganese meta-tetrakis(N-ethylpyridinium-3-yl)porphyrin (MnTE-3-PyP) is a challenging topic, particularly because of the high likelihood for their clinical development. Hence, a detailed study of the protolytic and electrochemical speciation of Mn(II-IV)TE-2-PyP and Mn(II-IV)TE-3-PyP in a broad pH range has been performed using the combined spectrophotometric and potentiometric methods. The results reveal that in aqueous solutions within the pH range ∼2-13 the following species exist: (H(2)O)Mn(II)TE-m-PyP(4+), (HO)Mn(II)TE-m-PyP(3+), (H(2)O)(2)Mn(III)TE-m-PyP(5+), (HO)(H(2)O)Mn(III)TE-m-PyP(4+), (O)(H(2)O)Mn(III)TE-m-PyP(3+), (O)(H(2)O)Mn(IV)TE-m-PyP(4+) and (O)(HO)Mn(IV)TE-m-PyP(3+) (m = 2, 3). All the protolytic equilibrium constants that include the accessible species as well as the thermodynamic parameters for each particular protolytic equilibrium have been determined. The corresponding formal reduction potentials related to the reduction of the above species and the thermodynamic parameters describing the accessible reduction couples were calculated as well.

Water exchange rates of water-soluble manganese(III) porphyrins of therapeutical potential

The activation parameters and the rate constants of the water-exchange reactions of Mn(III)TE-2-PyP(5+) (meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin) as cationic, Mn(III)TnHex-2-PyP(5+) (meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin) as sterically shielded cationic, and Mn(III)TSPP(3-) (meso-tetrakis(4-sulfonatophenyl)porphyrin) as anionic manganese(iii) porphyrins were determined from the temperature dependence of (17)O NMR relaxation rates. The rate constants at 298 K were obtained as 4.12 x 10(6) s(-1), 5.73 x 10(6) s(-1), and 2.74 x 10(7) s(-1), respectively. On the basis of the determined entropies of activation, an interchange-dissociative mechanism (I(d)) was proposed for the cationic complexes (DeltaS(double dagger) = approximately 0 J mol(-1) K(-1)) whereas a limiting dissociative mechanism (D) was proposed for Mn(III)TSPP(3-) complex (DeltaS(double dagger) = +79 J mol(-1) K(-1)). The obtained water exchange rate of Mn(III)TSPP(3-) corresponded well to the previously assumed value used by Koenig et al. (S. H. Koenig, R. D. Brown and M. Spiller, Magn. Reson. Med., 1987, 4, 52-260) to simulate the (1)H NMRD curves, therefore the measured value supports the theory developed for explaining the anomalous relaxivity of Mn(III)TSPP(3-) complex. A magnitude of the obtained water-exchange rate constants further confirms the suggested inner sphere electron transfer mechanism for the reactions of the two positively charged Mn(iii) porphyrins with the various biologically important oxygen and nitrogen reactive species. Due to the high biological and clinical relevance of the reactions that occur at the metal site of the studied Mn(iii) porphyrins, the determination of water exchange rates advanced our insight into their efficacy and mechanism of action, and in turn should impact their further development for both diagnostic (imaging) and therapeutic purposes.