Antimutageno djelovanje vitamina C na oksidacijske promjene uzrokovane kinolonima

Quinolones are broad-spectrum antibiotics effective against both Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) generated by quinolones may damage cell structures and could be a risk to health. The use of vitamin C to reduce such risks may have the opposite effects: vitamin C in the presence of divalent metal ions can induce the Fenton reaction, leading to hydroxyl radical (HO˙) generation and oxidative damage. The purpose of this study is to evaluate the antioxidant and prooxidant properties of vitamin C by measuring its effects on both lipid peroxidation and mutagenesis induced by quinolones nalidixic acid (NLX) or norfloxacin (NOR) in Salmonella typhimurium TA102. Mutagenicity was evaluated by the Ames test and the results were expressed as (histidine+ revertants/ng of quinolone), while lipoperoxidation was measured as thiobarbituric acid reactive substances (μmol malondialdehyde/(mL·h)). The effects of different concentrations of nalidixic acid (10–1000 ng) or norfloxacin (7–700 ng) on S. typhimurium TA102 were studied, employing the S9 mix (liver homogenate from rats pre-treated with Arochlor 1254) in the presence of 10–1000 μg of ascorbic acid (AA) with 0.1 mM FeCl3 or EDTA. Minimal inhibitory concentrations of NOR and NLX against 25 uropathogenic Escherichia coli strains were obtained using the plate dilution method in the presence of vitamin C. Vitamin C (1 mg) together with 0.1 mM FeCl3 showed a prooxidant effect in the S9 mix and enhanced the lipoperoxidation induced by either NOR or NLX. Mutagenic potency was also increased for both NOR and NLX. When metal ions were chelated with EDTA, ascorbate showed both antimutagenic and antioxidant properties. Mutagenic potency and lipoperoxidation were reduced for both NOR and NLX. The addition of vitamin C did not change the minimal in vitro inhibitory concentrations of NLX or NOR against the 25 uropathogenic E. coli strains. The antimutagenic and antioxidant effects of vitamin C were especially marked when the Salmonella strain was exposed to NOR or NLX in the presence of EDTA. In contrast, the vitamin C in the presence of FeCl3 increased ROS generation, enhancing both the mutagenic effect of the quinolones and malondialdehyde production from lipoperoxidation induced in the bacterial membranes. Therapeutic use of quinolones together with vitamin C and divalent cations might induce the Fenton reaction involving norfloxacin and nalidixic acid. However, our results suggest that vitamin C could be a good alternative for reducing the genotoxic risk of these therapeutic drugs if it is carefully handled.Kinoloni su antibiotici širokog spektra koji djeluju na Gram-pozitivne i Gram-negativne bakterije. Stvaraju reaktivne metabolite kisika što mogu oštetiti strukturu stanica i time narušiti zdravlje ljudi. Da bi se taj rizik smanjio, koristi se vitamin C koji međutim može imati i suprotno djelovanje: u prisutnosti dvovalentnih iona metala potiče Fentonovu reakciju, što dovodi do stvaranja hidroksil radikala (HO˙) koji oštećuju stanicu. Svrha je ovoga rada utvrditi antioksidativna i prooksidativna svojstva vitamina C ispitivanjem njegova utjecaja na peroksidaciju lipida i mutagenezu induciranu kinolonima poput nalidiksinske kiseline i norfloksacina iz soja bakterije Salmonella typhimurium TA102. Mutagenost je procijenjena Amesovim testom, a rezultati su izraženi kao broj revertanata histidin+/ng kinolona. Peroksidacija lipida mjerena je reakcijom produkata s tiobarbiturnom kiselinom, te izražena kao μmol malonaldehida/(mL·h). Istražen je utjecaj različitih koncentracija nalidiksinske kiseline (10-1000 ng) ili norfloksacina (7-700 ng) na bakteriju S. typhimurium TA102 pomoću mješavine S9 (homogenat jetre štakora tretiranih aroklorom 1254), 10-1000 μg vitamina C i 0,1 mM FeCl3 ili etilendiamintetraoctene kiseline (EDTA). Najmanje koncentracije norfloksacina i nalidiksinske kiseline, potrebne za inhibiciju 25 uropatogenih sojeva bakterije Escherichia coli, određene su metodom na agaru u prisutnosti vitamina C. Vitamin C (1 mg) uz 0,1 mM FeCl3 imao je prooksidativno djelovanje u mješavini S9, pospješio je peroksidaciju lipida uzrokovanu norfloksacinom ili nalidiksinskom kiselinom, te pojačao mutagenost oba kinolona. Stvaranje kelatnog kompleksa iona metala s EDTA potaknulo je antimutageno i antioksidativno djelovanje vitamina C, te smanjilo mutageno i lipoperoksidacijsko djelovanje norfloksacina i nalidiksinske kiseline. Dodatak vitamina C nije smanjio minimalnu koncentraciju nalidiksinske kiseline i norfloksacina in vitro, potrebnu za inhibiciju 25 uropatogenih sojeva bakterije E. coli. Antimutageno i antioksidativno djelovanje vitamina C bilo je osobito izraženo kada je soj bakterije Salmonella izložen djelovanju norfloksacina ili nalidiksinske kiseline u prisutnosti EDTA. Zajedno s FeCl3 vitamin C je ubrzao stvaranje reaktivnih metabolita kisika, pojačavajući time mutageno djelovanje kinolona te proizvodnju malondialdehida peroksidacijom lipida u membrani bakterija. Uporaba kinolona u kombinaciji s vitaminom C i dvovalentnim kationima pri liječenju bolesti mogla bi pokrenuti Fentonovu reakciju s norfloksacinom i nalidiksinskom kiselinom. Međutim, rezultati autora pokazuju da bi se vitamin C, pravilnom primjenom, mogao upotrijebiti kako bi se smanjila opasnost od genotoksičnog djelovanja tih lijekova

Populist Mobilization: A New Theoretical Approach to Populism*

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112280/1/j.1467-9558.2011.01388.x.pd

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Causes, consequences and biomarkers of stress in swine: an update

BACKGROUND: In recent decades there has been a growing concern about animal stress on intensive pig farms due to the undesirable consequences that stress produces in the normal physiology of pigs and its effects on their welfare and general productive performance. This review analyses the most important types of stress (social, environmental, metabolic, immunological and due to human handling), and their biological consequences for pigs. The physio-pathological changes associated with stress are described, as well as the negative effects of stress on pig production. In addition an update of the different biomarkers used for the evaluation of stress is provided. These biomarkers can be classified into four groups according to the physiological system or axis evaluated: sympathetic nervous system, hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-gonadal axis and immune system. CONCLUSIONS: Stress it is a process with multifactorial causes and produces an organic response that generates negative effects on animal health and production. Ideally, a panel of various biomarkers should be used to assess and evaluate the stress resulting from diverse causes and the different physiological systems involved in the stress response. We hope that this review will increase the understanding of the stress process, contribute to a better control and reduction of potential stressful stimuli in pigs and, finally, encourage future studies and developments to better monitor, detect and manage stress on pig farms

The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Antimutagenic Effects of Vitamin C Against Oxidative Changes Induced by Quinolones

Quinolones are broad-spectrum antibiotics effective against both Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) generated by quinolones may damage cell structures and could be a risk to health. The use of vitamin C to reduce such risks may have the opposite effects: vitamin C in the presence of divalent metal ions can induce the Fenton reaction, leading to hydroxyl radical (HO˙) generation and oxidative damage. The purpose of this study is to evaluate the antioxidant and prooxidant properties of vitamin C by measuring its effects on both lipid peroxidation and mutagenesis induced by quinolones nalidixic acid (NLX) or norfloxacin (NOR) in Salmonella typhimurium TA102. Mutagenicity was evaluated by the Ames test and the results were expressed as (histidine+ revertants/ng of quinolone), while lipoperoxidation was measured as thiobarbituric acid reactive substances (μmol malondialdehyde/(mL·h)). The effects of different concentrations of nalidixic acid (10–1000 ng) or norfloxacin (7–700 ng) on S. typhimurium TA102 were studied, employing the S9 mix (liver homogenate from rats pre-treated with Arochlor 1254) in the presence of 10–1000 μg of ascorbic acid (AA) with 0.1 mM FeCl3 or EDTA. Minimal inhibitory concentrations of NOR and NLX against 25 uropathogenic Escherichia coli strains were obtained using the plate dilution method in the presence of vitamin C. Vitamin C (1 mg) together with 0.1 mM FeCl3 showed a prooxidant effect in the S9 mix and enhanced the lipoperoxidation induced by either NOR or NLX. Mutagenic potency was also increased for both NOR and NLX. When metal ions were chelated with EDTA, ascorbate showed both antimutagenic and antioxidant properties. Mutagenic potency and lipoperoxidation were reduced for both NOR and NLX. The addition of vitamin C did not change the minimal in vitro inhibitory concentrations of NLX or NOR against the 25 uropathogenic E. coli strains. The antimutagenic and antioxidant effects of vitamin C were especially marked when the Salmonella strain was exposed to NOR or NLX in the presence of EDTA. In contrast, the vitamin C in the presence of FeCl3 increased ROS generation, enhancing both the mutagenic effect of the quinolones and malondialdehyde production from lipoperoxidation induced in the bacterial membranes. Therapeutic use of quinolones together with vitamin C and divalent cations might induce the Fenton reaction involving norfloxacin and nalidixic acid. However, our results suggest that vitamin C could be a good alternative for reducing the genotoxic risk of these therapeutic drugs if it is carefully handled