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Greussing R, Hackl M, Charoentong P, Pauck A, Monteforte R, Cavinato M, Hofer E, Scheideler M, Neuhaus M, Micutkova L, Mueck C, Trajanoski Z, Grillari J, Jansen-Dürr P. Identification of microRNA-mRNA functional interactions in UVB-induced senescence of human diploid fibroblasts. BMC Genomics 2013; 14:224. [PMID: 23557329 PMCID: PMC4008267 DOI: 10.1186/1471-2164-14-224] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 03/08/2013] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Cellular senescence can be induced by a variety of extrinsic stimuli, and sustained exposure to sunlight is a key factor in photoaging of the skin. Accordingly, irradiation of skin fibroblasts by UVB light triggers cellular senescence, which is thought to contribute to extrinsic skin aging, although molecular mechanisms are incompletely understood. Here, we addressed molecular mechanisms underlying UVB induced senescence of human diploid fibroblasts. RESULTS We observed a parallel activation of the p53/p21(WAF1) and p16(INK4a)/pRb pathways. Using genome-wide transcriptome analysis, we identified a transcriptional signature of UVB-induced senescence that was conserved in three independent strains of human diploid fibroblasts (HDF) from skin. In parallel, a comprehensive screen for microRNAs regulated during UVB-induced senescence was performed which identified five microRNAs that are significantly regulated during the process. Bioinformatic analysis of miRNA-mRNA networks was performed to identify new functional mRNA targets with high confidence for miR-15a, miR-20a, miR-20b, miR-93, and miR-101. Already known targets of these miRNAs were identified in each case, validating the approach. Several new targets were identified for all of these miRNAs, with the potential to provide new insight in the process of UVB-induced senescence at a genome-wide level. Subsequent analysis was focused on miR-101 and its putative target gene Ezh2. We confirmed that Ezh2 is regulated by miR-101 in human fibroblasts, and found that both overexpression of miR-101 and downregulation of Ezh2 independently induce senescence in the absence of UVB irradiation. However, the downregulation of miR-101 was not sufficient to block the phenotype of UVB-induced senescence, suggesting that other UVB-induced processes induce the senescence response in a pathway redundant with upregulation of miR-101. CONCLUSION We performed a comprehensive screen for UVB-regulated microRNAs in human diploid fibroblasts, and identified a network of miRNA-mRNA interactions mediating UVB-induced senescence. In addition, miR-101 and Ezh2 were identified as key players in UVB-induced senescence of HDF.
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Hofer E, Sanchez-Quintana D, Arnold R. Rapid Pacing Induces Fractionation of the Activation Wavefront into Multiple Wavelets. BIOMED ENG-BIOMED TE 2013; 58 Suppl 1:/j/bmte.2013.58.issue-s1-S/bmt-2013-4421/bmt-2013-4421.xml. [DOI: 10.1515/bmt-2013-4421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Arnold R, Hofer E. Variations in Pacing Dynamics Result in Different Heterogeneity and Development of Conduction Block. BIOMED ENG-BIOMED TE 2013; 58 Suppl 1:/j/bmte.2013.58.issue-s1-S/bmt-2013-4422/bmt-2013-4422.xml. [DOI: 10.1515/bmt-2013-4422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Oliveira I, Almeida R, Hofer E, Almeida P. Bacteriophage amplification assay for detection of Listeria spp. using virucidal laser treatment. Braz J Microbiol 2012. [DOI: 10.1590/s1517-83822012000300040] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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105
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Althaus D, Hofer E, Corti S, Julmi A, Stephan R. Bacteriological survey of ready-to-eat lettuce, fresh-cut fruit, and sprouts collected from the Swiss market. J Food Prot 2012; 75:1338-41. [PMID: 22980021 DOI: 10.4315/0362-028x.jfp-12-022] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The consumption of ready-to-eat fresh vegetables has increased significantly in the recent decades. So far, no data are available on the bacteriological burden and the prevalence of foodborne pathogens in ready-to-eat lettuce, fresh-cut fruit, and sprouts on the Swiss market. This study was based on investigations carried out during 2 months of the summer season in 2011. Samples of 142 salads, 64 fresh-cut fruit, and 27 sprouts were included in this study. Escherichia coli, an indicator microorganism for fecal contamination, was only found in 5 lettuce samples, with amounts ranging between 2 and 3 log CFU/g. No Salmonella spp. were detected from any of the 233 samples analyzed in this study, and a low occurrence was found for contamination with L. monocytogenes, Shiga toxin-producing E. coli, enteropathogenic E. coli, and Cronobacter. From the results of the present study, we conclude that even in a country where the use of chlorine solutions to sanitize fruits and vegetables in the fresh-cut industry is not allowed, it is possible to produce ready-to-eat lettuce, fresh-cut fruit, and sprouts with high microbiological standards. Strict maintenance of good practices of hygiene at preharvest, harvest, and postharvest levels is of central importance to ensure both public health protection and product quality.
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Sattler S, Reiche D, Sturtzel C, Karas I, Richter S, Kalb ML, Gregor W, Hofer E. The human C-type lectin-like receptor CLEC-1 is upregulated by TGF-β and primarily localized in the endoplasmic membrane compartment. Scand J Immunol 2012; 75:282-92. [PMID: 22117783 DOI: 10.1111/j.1365-3083.2011.02665.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The orphan receptor CLEC-1 is part of a subfamily of C-type lectin-like receptors, which is encoded in the human natural killer gene complex and comprises several pattern recognition receptors important for innate immune functions. As information on human CLEC-1 is still very limited, we aimed to further characterize this receptor. Similar to another subfamily member, LOX-1, expression of CLEC-1 mRNA was detected in myeloid cells as well as in endothelial cells. CLEC-1 protein displayed N-linked glycosylation and formed dimers. However, in contrast to other members of the subfamily, expression levels were upregulated by transforming growth factor (TGF)-β, but not significantly affected by proinflammatory stimuli. It is intriguing that human CLEC-1 could only be detected intracellularly with a staining pattern resembling endoplasmic reticulum proteins. Neither TGF-β nor inflammatory stimuli could promote significant translocation to the cell surface. These findings are in accordance with a primarily intracellular localization and function of human CLEC-1.
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Arnold R, Wiener T, Sanchez-Quintana D, Hofer E. Topology and conduction in the inferior right atrial isthmus measured in rabbit hearts. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:247-50. [PMID: 22254296 DOI: 10.1109/iembs.2011.6090047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The inferior right atrial isthmus consisting of the terminal crest, the network of pectinate muscles, and the vestibule shows very complex anatomical structure. It is seen as potential substrate for atrial flutter. In this work we present results from an electro-anatomical characterization of this region based on Cardiac Near Field recordings taken from five preparations of rabbit atrium. Pectinate muscles in the region of interest were divided into three segments: central as well as proximal and distal with respect to the terminal crest. Electrograms measured in these segments showed differences in the degree of fractionation, i.e. the numbers of distinct local activation events, indicating heterogeneities in microstructure. From 249 recording sites 63.9% showed no fractionation, 26.9% showed two activation events, and 9.2% were highly fractionated. The proximal starting sequence of activation in a series of adjacent pectinate muscles is not sorted but rather seems to be arbitrary. The same applies to the arrival sequence of activation close to the vestibule. In the network of pectinate muscles on average one proximal segment branches into two central strands and two central strands merge into one distal stem.
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Oliveira IC, Almeida RCC, Hofer E, Almeida PF. Bacteriophage amplification assay for detection of Listeria spp. using virucidal laser treatment. Braz J Microbiol 2012; 43:1128-36. [PMID: 24031937 PMCID: PMC3768892 DOI: 10.1590/s1517-838220120003000040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 06/07/2012] [Indexed: 11/22/2022] Open
Abstract
A protocol for the bacteriophage amplification technique was developed for quantitative detection of viable Listeria monocytogenes cells using the A511 listeriophage with plaque formation as the end-point assay. Laser and toluidine blue O (TBO) were employed as selective virucidal treatment for destruction of exogenous bacteriophage. Laser and TBO can bring a total reduction in titer phage (ca. 10(8) pfu/mL) without affecting the viability of L. monocytogenes cells. Artificially inoculated skimmed milk revealed mean populations of the bacteria as low as between 13 cfu/mL (1.11 log cfu/mL), after a 10-h assay duration. Virucidal laser treatment demonstrated better protection of Listeria cells than the other agents previously tested. The protocol was faster and easier to perform than standard procedures. This protocol constitutes an alternative for rapid, sensitive and quantitative detection of L. monocytogenes.
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Hevesy GV, Hofer E, Krogh A. The permeability of the skin of frogs to water as determined by D2O and H2O1. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/j.1748-1716.1935.tb00423.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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110
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Hofer E, Stephan R, Reist M, Zweifel C. Application of a real-time PCR-based system for monitoring of O26, O103, O111, O145 and O157 Shiga toxin-producing Escherichia coli in cattle at slaughter. Zoonoses Public Health 2012; 59:408-15. [PMID: 22348425 DOI: 10.1111/j.1863-2378.2012.01468.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Faecal samples were collected from 573 slaughtered cattle aged between three and 24 months in seven abattoirs. After enrichment (mTSB with novobiocin), samples were screened by real-time PCR first for stx and if positive, tested for the top-five Shiga toxin-producing Escherichia coli (STEC) serogroups using PCR assays targeting genes specific for serogroups O26, O103, O111, O145 and O157. Of 563 samples with available results, 74.1% tested positive for stx genes. Amongst them, the serogroups O145, O103, O26, O157 and O111 were detected in 41.9%, 25.9%, 23.9%, 7.8% and 0.8%, respectively. From 95 O26, 166 O145 and 30 O157 PCR-positive samples, 17 O26, 28 O145 and 12 O157 strains were isolated by colony hybridization after immunomagnetic separation. The 17 O26 strains were eae-positive, but only nine strains harboured stx (eight possessing stx1 and one stx2). Of the 28 O145 strains, ten were eae-positive including four harbouring stx1 or stx2, whereas 18 were negative for stx and eae. Five of the 12 O157 strains harboured stx2 and eae, did not ferment sorbitol, and were identified as STEC O157:H7/H⁻. The other seven O157 strains were negative for stx and eae or positive only for eae. Shiga toxin genes and the top-five STEC serogroups were frequently found in young Swiss cattle at slaughter, but success rates for strain isolation were low and only few strains showed a virulence pattern of human pathogenic STEC.
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Arnold R, Wiener T, Schwarz M, Hofer E. Circumferential Pacing Reveals Microstructure of Cardiac Tissue Preparations from Small Animals – An Approach to Classify Microfibrosis. BIOMED ENG-BIOMED TE 2012. [DOI: 10.1515/bmt-2012-4393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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112
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Hofer E, Laschober GT, Hackl M, Thallinger GG, Lepperdinger G, Grillari J, Jansen-Dürr P, Trajanoski Z. GiSAO.db: a database for ageing research. BMC Genomics 2011; 12:262. [PMID: 21609420 PMCID: PMC3113790 DOI: 10.1186/1471-2164-12-262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/24/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Age-related gene expression patterns of Homo sapiens as well as of model organisms such as Mus musculus, Saccharomyces cerevisiae, Caenorhabditis elegans and Drosophila melanogaster are a basis for understanding the genetic mechanisms of ageing. For an effective analysis and interpretation of expression profiles it is necessary to store and manage huge amounts of data in an organized way, so that these data can be accessed and processed easily. DESCRIPTION GiSAO.db (Genes involved in senescence, apoptosis and oxidative stress database) is a web-based database system for storing and retrieving ageing-related experimental data. Expression data of genes and miRNAs, annotation data like gene identifiers and GO terms, orthologs data and data of follow-up experiments are stored in the database. A user-friendly web application provides access to the stored data. KEGG pathways were incorporated and links to external databases augment the information in GiSAO.db. Search functions facilitate retrieval of data which can also be exported for further processing. CONCLUSIONS We have developed a centralized database that is very well suited for the management of data for ageing research. The database can be accessed at https://gisao.genome.tugraz.at and all the stored data can be viewed with a guest account.
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Laschober GT, Ruli D, Hofer E, Muck C, Carmona-Gutierrez D, Ring J, Hutter E, Ruckenstuhl C, Micutkova L, Brunauer R, Jamnig A, Trimmel D, Herndler-Brandstetter D, Brunner S, Zenzmaier C, Sampson N, Breitenbach M, Fröhlich KU, Grubeck-Loebenstein B, Berger P, Wieser M, Grillari-Voglauer R, Thallinger GG, Grillari J, Trajanoski Z, Madeo F, Lepperdinger G, Jansen-Dürr P. Identification of evolutionarily conserved genetic regulators of cellular aging. Aging Cell 2010; 9:1084-97. [PMID: 20883526 PMCID: PMC2997327 DOI: 10.1111/j.1474-9726.2010.00637.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
To identify new genetic regulators of cellular aging and senescence, we performed genome-wide comparative RNA profiling with selected human cellular model systems, reflecting replicative senescence, stress-induced premature senescence, and distinct other forms of cellular aging. Gene expression profiles were measured, analyzed, and entered into a newly generated database referred to as the GiSAO database. Bioinformatic analysis revealed a set of new candidate genes, conserved across the majority of the cellular aging models, which were so far not associated with cellular aging, and highlighted several new pathways that potentially play a role in cellular aging. Several candidate genes obtained through this analysis have been confirmed by functional experiments, thereby validating the experimental approach. The effect of genetic deletion on chronological lifespan in yeast was assessed for 93 genes where (i) functional homologues were found in the yeast genome and (ii) the deletion strain was viable. We identified several genes whose deletion led to significant changes of chronological lifespan in yeast, featuring both lifespan shortening and lifespan extension. In conclusion, an unbiased screen across species uncovered several so far unrecognized molecular pathways for cellular aging that are conserved in evolution.
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Sattler S, Ghadially H, Reiche D, Karas I, Hofer E. Evolutionary Development and Expression Pattern of the Myeloid Lectin-Like Receptor Gene Family Encoded Within the NK Gene Complex. Scand J Immunol 2010; 72:309-18. [DOI: 10.1111/j.1365-3083.2010.02433.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Cariri FAMO, Costa APR, Melo CC, Theophilo GND, Hofer E, de Melo Neto OP, Leal NC. Characterization of potentially virulent non-O1/non-O139 Vibrio cholerae strains isolated from human patients. Clin Microbiol Infect 2010; 16:62-7. [PMID: 19456828 DOI: 10.1111/j.1469-0691.2009.02763.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Traditional methods of typing Vibrio cholerae define virulent strains according to their recognition by sera directed against the known epidemic serogroups O1 and O139, overlooking potentially virulent non-O1/non-O139 strains. Here, we have undertaken the characterization of eight clinical isolates of non-O1/non-O139 V. cholerae, collected during cholera outbreaks in Brazil. Seven of these were typed as O26 and one, 17155, was defined as non-typable. A PCR-based approach has previously detected in these strains several virulence genes derived from the CTXvarphi prophage and generally associated with pathogenic strains. Here, the presence of the O1-specific wbeN gene was investigated through PCR and found to be restricted to strain 17155, as well as one of the O26 strains, 4756, although neither strain was recognized by O1-specific antisera. The same two isolates were the only strains able to express the cholera toxin in culture, assayed by western blotting. They also possessed four repeats of the heptanucleotide TTTTGAT upstream of the ctxAB genes encoding the cholera toxin. The remaining strains possessed only two intact repeats, whereas pathogenic O1 possessed four to six repeats. To define their evolutionary relationships, selected 16S-23S intergenic rRNA spacer regions were sequenced from the various strains and the resulting sequences used to build phylogenetic trees. Strains 4756 and 17155 always clustered with control O1 strains, whereas the remaining O26 strains clustered separately. These results confirm that, despite their serological phenotype, these two strains are genotypically related to O1 strains and potentially able to produce epidemic cholera.
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Weber dos Santos R, Steinhoff U, Hofer E, Sanchez-Quintana D, Koch H. MODELLING THE ELECTRICAL PROPAGATION IN CARDIAC TISSUE USING DETAILED HISTOLOGICAL DATA. ACTA ACUST UNITED AC 2009. [DOI: 10.1515/bmte.2003.48.s1.476] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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117
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Volkheimer G, Schulz F, Hofer E, Schicht J. Coffeinwirkung auf die Persorptionsrate. ANNALS OF NUTRITION AND METABOLISM 2008. [DOI: 10.1159/000175236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Leal N, da Silva S, Cavalcanti V, Figueiroa ÂDA, Nunes V, Miralles I, Hofer E. Vibrio parahaemolyticusserovar O3:K6 gastroenteritis in northeast Brazil. J Appl Microbiol 2008; 105:691-7. [DOI: 10.1111/j.1365-2672.2008.03782.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hofer E, Keplinger F, Thurner T, Wiener T, Sanchez-Quintana D, Climent V, Plank G. A new floating sensor array to detect electric near fields of beating heart preparations. Biosens Bioelectron 2006; 21:2232-9. [PMID: 16384696 DOI: 10.1016/j.bios.2005.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 11/05/2005] [Accepted: 11/15/2005] [Indexed: 10/25/2022]
Abstract
A new flexible sensor for in vitro experiments was developed to measure the surface potential, Phi, and its gradient, E (electric near field), at given sites of the heart. During depolarisation, E describes a vector loop from which direction and magnitude of local conduction velocity theta can be computed. Four recording silver electrodes (14 microm x 14 microm) separated by 50 microm, conducting leads, and solderable pads were patterned on a 50 microm thick polyimide film. The conductive structures, except the electrodes, were isolated with polyimide, and electrodes were chlorided. Spacer pillars mounted on the tip fulfil two functions: they keep the electrodes 70 microm from the tissue allowing non-contact recording of Phi and prevent lateral slipping. The low mass (9.1 mg) and flexibility (6.33 N/m) of the sensor let it easily follow the movement of the beating heart without notable displacement. We examined the electrodes on criteria like rms-noise of Phi, signal-to-noise ratio of Phi and E, maximum peak-slope recording dPhi/dt, and deviation of local activation time (LAT) from a common signal and obtained values of 24-28 microV, 46 and 41 dB, 497-561 V/s and no differences, respectively. With appropriate data acquisition (sampling rate 100 kHz, 24-bit), we were able to record Phi and to monitor E and theta on-line from beat-to-beat even at heart rates of 600 beats/min. Moreover, this technique can discriminate between uncoupled cardiac activations (as occur in fibrotic tissue) separated by less than 1 mm and 1 ms.
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Windhofer C, Gruber S, Hofer E, Papp C. Free flap survival despite severe anemia after fourth degree hand burn. Burns 2006; 32:261-5. [PMID: 16451819 DOI: 10.1016/j.burns.2005.06.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2005] [Accepted: 06/30/2005] [Indexed: 10/25/2022]
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Majer BJ, Hofer E, Cavin C, Lhoste E, Uhl M, Glatt HR, Meinl W, Knasmüller S. Coffee diterpenes prevent the genotoxic effects of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and N-nitrosodimethylamine in a human derived liver cell line (HepG2). Food Chem Toxicol 2005; 43:433-41. [PMID: 15680679 DOI: 10.1016/j.fct.2004.11.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2004] [Accepted: 11/03/2004] [Indexed: 10/26/2022]
Abstract
Aim of the present experiments was to study the genotoxic effects of coffee diterpenoids, namely cafestol palmitate and a mix of cafestol and kahweol (C+K) in human derived hepatoma (HepG2) cells. Furthermore, we investigated the potential protective properties of these substances towards carcinogens contained in the human diet, namely N-nitrosodimethylamine (NDMA) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). C+K and cafestol palmitate were tested over a broad dose range in micronucleus (MN) assays and no indication for genotoxic effects was seen. In combination experiments with PhIP (300 microM), pronounced inhibition (approximately 1.7-fold) of MN formation was observed with C+K and cafestol palmitate at dose levels > or = 0.9 and 1.7 microg/ml, respectively. Enzyme measurements indicate that the protection is due to inhibition of sulfotransferase, an enzyme involved in the activation of the amine, and/or to induction of UDP-glucuronosyltransferase which detoxifies the DNA-reactive metabolites of PhIP. Furthermore, a significant increase of glutathione-S-transferase was seen, whereas the activities of cytochrome P-450 1A1 and N-acetyltransferase 1 were not significantly altered. Also in combination experiments with C+K and NDMA, strong protective effects (50% reduction of genotoxicity) were seen at low dose levels (> or = 0.3 microg/ml). Since inhibition of MN was also observed when C+K were added after incubation with NDMA, it is likely that the chemoprotective effects are due to induction of DNA repair enzymes. Comparison of data on the effects of C+K on the cholesterol metabolism, which was investigated in earlier in vivo studies, with the present findings suggests that DNA-protective effects take place at exposure levels which are substantially lower than those which cause hypercholesterolemia.
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Bardow A, Hofer E, Nyvad B, ten Cate JM, Kirkeby S, Moe D, Nauntofte B. Effect of Saliva Composition on Experimental Root Caries. Caries Res 2004; 39:71-7. [PMID: 15591738 DOI: 10.1159/000081660] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Accepted: 07/24/2004] [Indexed: 11/19/2022] Open
Abstract
The aim of this study was to determine the effect of saliva composition on caries lesion development independently of the flow rate of unstimulated whole saliva (UWS) and other caries-related variables such as lesion progression time, oral hygiene level, and fluoride exposure. We hypothesized that this could be done by developing experimental root caries under carefully controlled conditions in situ in test subjects with UWS flow rates within a narrow window of normalcy. Fifteen female and 5 male subjects (66 +/- 6 years) were selected for the study according to their UWS flow rates between 0.2 and 0.4 ml/min. All subjects developed experimental root caries lesions during a 62-day period in which UWS as well as stimulated whole saliva (SWS) were repeatedly collected and analysed for flow rate, pH, buffer capacity, inorganic, and organic composition. Caries lesion development was determined by quantitative microradiography. The mean UWS flow rate was 0.30 +/- 0.05 ml/min. Significant negative correlations were obtained between UWS total phosphate concentration and mineral loss (DeltaZ; r(s) = -0.72, p < 0.001) and UWS total protein concentration and DeltaZ (r(s) = -0.70, p < 0.01). SWS and its constituents had only limited or no effect on DeltaZ. Qualitative UWS protein analysis (SDS-PAGE) revealed that subjects with low DeltaZ values had broader and more stained amylase bands than subjects with high DeltaZ values. These findings were confirmed quantitatively by HPLC. We conclude that, within a group of subjects with normal UWS flow rates, the UWS composition was more important for caries lesion development than the SWS composition. Furthermore, high UWS concentrations of phosphate, protein, and amylase were caries-protective.
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Long JR, Zhang YY, Hofer E, Seemann C, Schatz M, O'Brien D, Deng HW. Rapid Purification of High Quality DNA from Large Whole Blood Samples Using a New Rapid Protocol. Eng Life Sci 2004. [DOI: 10.1002/elsc.200420040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Plank G, Vigmond E, Leon LJ, Hofer E. Cardiac near-field morphology during conduction around a microscopic obstacle--a computer simulation study. Ann Biomed Eng 2004; 31:1206-12. [PMID: 14649494 DOI: 10.1114/1.1615573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In a recent paper, we described the behavior of the cardiac electric near-field, E, parallel to the tissue surface during continuous conduction. We found that the tip of E describes a vector-loop during depolarization with the peak field, E, pointing opposite to the direction of propagation, phiI(m). Experimentally recorded loop morphologies of E, however, frequently showed significant deviations from the theoretically predicted behavior. We hypothesized that this variety of morphologies might be caused by conduction obstacles at a microscopic size scale. This study examines the influence of obstacles on the morphology of vector loops of E and whether the peak of distorted loops remains a reliable indicator for the direction of propagation. We used a computer model of a sheet of cardiac tissue with a central conduction obstacle immersed in an unbounded volume conductor. We studied the loop morphologies of E and the differences between the intracellularly determined direction of propagation, phiI(m), and the direction of E, phiE. Distortions of the vector loop were morphologically similar to those observed experimentally. Differences between phiI(m) and phiE were less than 18 degrees at all observation sites. The obstacle led to deformations of the loop morphology, particularly during the initial and terminal phases, and to a lesser degree near the instant of E. We concluded that E is a reliable indicator of phiI(m).
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Leal NC, Sobreira M, Leal-Balbino TC, de Almeida AMP, de Silva MJB, Mello DM, Seki LM, Hofer E. Evaluation of a RAPD-based typing scheme in a molecular epidemiology study of Vibrio cholerae O1, Brazil. J Appl Microbiol 2004; 96:447-54. [PMID: 14962124 DOI: 10.1111/j.1365-2672.2004.02090.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To evaluate the utility of random amplification of polymorphic DNA (RAPD) technique for routine practice in public health laboratories for epidemiological studies of Vibrio cholerae O1 isolates. MATERIALS AND RESULTS Seventy-nine strains were examined by PCR for the toxin genes (ctx A, zot and ace), virulence-associated genes (tcp A and tox T) and RAPD sequences. Except for one strain (no. 1123) from the Amazonas State, all the strains analysed carried the genes ctx A, zot, ace, tcp A and tox T. RAPD fingerprinting revealed variability but no correlation with serotype, biotype or geographical origin of the isolates was found. CONCLUSION A standardized RAPD method does not enable the establishment of a pattern data bank for the identification of V. cholerae O1 strains. SIGNIFICANCE AND IMPACT OF THE STUDY The simplicity and discriminative capacity of this technique make it useful for detecting genetic diversity among micro-organisms from a defined group or for outbreak investigation.
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