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  1. Role of Deubiquitinating Enzymes in DNA Repair

    OpenAIRE

    2016-01-01

    Both proteolytic and nonproteolytic functions of ubiquitination are essential regulatory mechanisms for promoting DNA repair and the DNA damage response in mammalian cells. Deubiquitinating enzymes (DUBs) have emerged as key players in the maintenance of genome stability. In this minireview, we discuss the recent findings on human DUBs that participate in genome maintenance, with a focus on the role of DUBs in the modulation of DNA repair and DNA damage signaling.

  2. Putative Enzymes of UV Photoproduct Repair

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    Cynthia J. Sakofsky

    2011-01-01

    Full Text Available In order to determine the biological relevance of two S. acidocaldarius proteins to the repair of UV photoproducts, the corresponding genes (Saci_1227 and Saci_1096 were disrupted, and the phenotypes of the resulting mutants were examined by various genetic assays. The disruption used integration by homologous recombination of a functional but heterologous pyrE gene, promoted by short sequences attached to both ends via PCR. The phenotypic analyses of the disruptants confirmed that ORF Saci_1227 encodes a DNA photolyase which functions in vivo, but they could not implicate ORF Saci_1096 in repair of UV- or other externally induced DNA damage despite its similarity to genes encoding UV damage endonucleases. The success of the gene-disruption strategy, which used 5′ extensions of PCR primers to target cassette integration, suggests potential advantages for routine construction of Sulfolobus strains.

  3. A Rare Case of Laparoscopic Repair of Simultaneously Occurring Morgagni and Paraesophageal Hernias.

    Science.gov (United States)

    Zhou, Zu-Li; Li, Hao; Li, Jian-Feng; Liu, Yan-Guo; Wang, Chong; Wang, Jun

    2016-01-01

    Simultaneously occurring Morgagni hernia and paraesophageal hernia is an extremely rare clinical condition with only six case reports in the English-language literature and only two laparoscopic repair reports. We report a 73-year-old woman with both Morgagni hernia and paraesophageal hernia who underwent successful laparoscopic repair of the hernia defects using transabdominal wall suturing. The laparoscopic operation can provide excellent exposure and repair the hernia defect easily with minimal invasiveness and fewer complications. This case report reported the concurring Morgagni and paraesophageal hernias and validated the feasibility of laparoscopic repair both hernias simultaneously.

  4. Do all hemolytic anemias that occur after mitral valve repair require surgical treatment?

    Science.gov (United States)

    Gungunes, Askin; Akpinar, Ibrahim; Dogan, Mehmet; Baser, Kazim; Yildirim, Ismail Safa; Haznedaroglu, Ibrahim C

    2010-12-01

    We report on a 29-year-old woman with severe hemolytic anemia following mitral valve annuloplasty. Although hemolysis due to mechanical prosthetic mitral valve is well recognized, hemolytic anemia associated with mitral valve repair is an uncommon condition. Reoperation may be considered if the patient has serious and persistent anemia. Although valve replacement is suggested to be a unique intervention, it may not be the solution every time because of mechanical effects. Various mechanisms of hemolysis related to mitral valve repair were suggested, but sufficient and precise data is not available. In this case, we tried to emphasize whether all hemolytic anemias that occur after mitral valve repair require surgical treatment.

  5. FISH comets show that the salvage enzyme TK1 contributes to gene-specific DNA repair

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    Stephen eDownes

    2014-08-01

    Full Text Available Thymidine kinase 1 (TK1 is a salvage enzyme that phosphorylates thymidine, imported from surrounding fluids, to create dTMP, which is further phosphorylated to the DNA precursor dTTP. TK1 deficiency has for a long time been known to cause increased cellular sensitivity to DNA damage. We have examined preferential strand break repair of DNA domains in TK1+ and TK1- clones of the Raji cell line, by the Comet-FISH technique, in bulk DNA and in the actively transcribed tumour suppressor (TP53 and human telomerase reverse transcriptase (hTERT gene regions, over 1 hour after 5Gy γ-irradiation. Results showed that repair of the TP53 and hTERT gene regions was more efficient in TK1+ compared to TK1- cells, while levels of genomic DNA repair were consistant between the two cell-lines. The targeted gene-specific repair in TK+ cells occurred rapidly, mainly over the first 15 minute repair-period. Therefore, TK1 is needed for preferential repair of actively transcribed regions, through a previously unsuspected mechanism. In principle, TK1 could exert its protective effects through supply of a supplementary dTTP pool for accurate repair of damaged genes; but Raji TK1+ cells in thymidine free media still show preferential repair of transcribed regions. TK1 therefore does not exert its protective effects through dTTP pools, but through another unidentified mechanism, which affects sensitivity to and mutagenicity by DNA damaging agents.

  6. FISH comets show that the salvage enzyme TK1 contributes to gene-specific DNA repair

    Science.gov (United States)

    McAllister, Katherine A.; Yasseen, Akeel A.; McKerr, George; Downes, C. S.; McKelvey-Martin, Valerie J.

    2014-01-01

    Thymidine kinase 1 (TK1) is a salvage enzyme that phosphorylates thymidine, imported from surrounding fluids, to create dTMP, which is further phosphorylated to the DNA precursor dTTP. TK1 deficiency has for a long time been known to cause increased cellular sensitivity to DNA damage. We have examined preferential strand break repair of DNA domains in TK1+ and TK1- clones of the Raji cell line, by the Comet-FISH technique, in bulk DNA and in the actively transcribed tumor suppressor (TP53) and human telomerase reverse transcriptase (hTERT) gene regions, over 1 h after 5Gy γ-irradiation. Results showed that repair of the TP53 and hTERT gene regions was more efficient in TK1+ compared to TK1- cells, a trend also reflected to a lesser degree in genomic DNA repair between the cell-lines. The targeted gene-specific repair in TK+ cells occurred rapidly, mainly over the first 15 min repair-period. Therefore, TK1 is needed for preferential repair of actively transcribed regions, through a previously unsuspected mechanism. In principle, TK1 could exert its protective effects through supply of a supplementary dTTP pool for accurate repair of damaged genes; but Raji TK1+ cells in thymidine free media still show preferential repair of transcribed regions. TK1 therefore does not exert its protective effects through dTTP pools, but through another unidentified mechanism, which affects sensitivity to and mutagenicity by DNA damaging agents. PMID:25152750

  7. Divergent Requirement for a DNA Repair Enzyme during Enterovirus Infections

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    Sonia Maciejewski

    2015-12-01

    Full Text Available Viruses of the Enterovirus genus of picornaviruses, including poliovirus, coxsackievirus B3 (CVB3, and human rhinovirus, commandeer the functions of host cell proteins to aid in the replication of their small viral genomic RNAs during infection. One of these host proteins is a cellular DNA repair enzyme known as 5′ tyrosyl-DNA phosphodiesterase 2 (TDP2. TDP2 was previously demonstrated to mediate the cleavage of a unique covalent linkage between a viral protein (VPg and the 5′ end of picornavirus RNAs. Although VPg is absent from actively translating poliovirus mRNAs, the removal of VPg is not required for the in vitro translation and replication of the RNA. However, TDP2 appears to be excluded from replication and encapsidation sites during peak times of poliovirus infection of HeLa cells, suggesting a role for TDP2 during the viral replication cycle. Using a mouse embryonic fibroblast cell line lacking TDP2, we found that TDP2 is differentially required among enteroviruses. Our single-cycle viral growth analysis shows that CVB3 replication has a greater dependency on TDP2 than does poliovirus or human rhinovirus replication. During infection, CVB3 protein accumulation is undetectable (by Western blot analysis in the absence of TDP2, whereas poliovirus protein accumulation is reduced but still detectable. Using an infectious CVB3 RNA with a reporter, CVB3 RNA could still be replicated in the absence of TDP2 following transfection, albeit at reduced levels. Overall, these results indicate that TDP2 potentiates viral replication during enterovirus infections of cultured cells, making TDP2 a potential target for antiviral development for picornavirus infections.

  8. Photoprotection by topical DNA repair enzymes: molecular correlates of clinical studies.

    Science.gov (United States)

    Yarosh, D B; O'Connor, A; Alas, L; Potten, C; Wolf, P

    1999-02-01

    A new approach to photoprotection is to repair DNA damage after UV exposure. This can be accomplished by delivery of a DNA repair enzyme with specificity to UV-induced cyclobutane pyrimidine dimers into skin by means of specially engineered liposomes. Treatment of DNA-repair-deficient xeroderma pigmentosum patients or skin cancer patients with T4N5 liposome lotion containing such DNA repair liposomes increases the removal of DNA damage in the first few hours after treatment. In these studies, a DNA repair effect was observed in some patients treated with heat-inactivated enzyme. Unexpectedly, it was discovered that the heat-inactivated T4 endonuclease V enzyme refolds and recovers enzymatic activity. These studies demonstrate that measurements of molecular changes induced by biological drugs are useful adjuvants to clinical studies.

  9. Enzymic and structural aspects of repair DNA synthesis activation in mammalian chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Belyakova, N.V.; Naryzhnyj, S.N.; Filatov, M.V.; Krutyakov, V.M. (AN SSSR, Leningrad. Inst. Yadernoj Fiziki)

    Analysis was made of the enzymic and structural factors responsible for activation of repair DNA synthesis in ..gamma..-irradiated chromatin isolated from rat liver or some human cells. The results obtained prompted us to reduce by 10-12 times the dose of radiation used before. With doses of 30 Gy and 10 Gy, the value of the original repair synthesis was doubled in the chromatin of rat liver and HeLa cells, respectively.

  10. Location of DNA damage by charge exchanging repair enzymes: effects of cooperativity on location time

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    Eriksen Kasper

    2005-04-01

    Full Text Available Abstract Background How DNA repair enzymes find the relatively rare sites of damage is not known in great detail. Recent experiments and molecular data suggest that individual repair enzymes do not work independently of each other, but interact with each other through charges exchanged along the DNA. A damaged site in the DNA hinders this exchange. The hypothesis is that the charge exchange quickly liberates the repair enzymes from error-free stretches of DNA. In this way, the sites of damage are located more quickly; but how much more quickly is not known, nor is it known whether the charge exchange mechanism has other observable consequences. Results Here the size of the speed-up gained from this charge exchange mechanism is calculated and the characteristic length and time scales are identified. In particular, for Escherichia coli, I estimate the speed-up is 50000/N, where N is the number of repair enzymes participating in the charge exchange mechanism. Even though N is not exactly known, a speed-up of order 10 is not entirely unreasonable. Furthermore, upon over expression of all the repair enzymes, the location time only varies as N-1/2 and not as 1/N. Conclusion The revolutionary hypothesis that DNA repair enzymes use charge exchange along DNA to locate damaged sites more efficiently is actually sound from a purely theoretical point of view. Furthermore, the predicted collective behavior of the location time is important in assessing the impact of stress-ful and radioactive environments on individual cell mutation rates.

  11. DNA repair enzymes: an important role in skin cancer prevention and reversal of photodamage--a review of the literature.

    Science.gov (United States)

    Kabir, Yasmeen; Seidel, Rachel; Mcknight, Braden; Moy, Ronald

    2015-03-01

    The incidence of skin cancer continues to increase annually despite preventative measures. Non-melanoma skin cancer affects more than 1,000,000 people in the United States every year.1 The current preventative measures, such as sunscreens and topical antioxidants, have not shown to be effective in blocking the effects of UV radiation based on these statistics. The level of antioxidants contained in the majority of skin creams is not sufficient to majorly impact free radical damage. Sunscreens absorb only a portion of UV radiation and often are not photostable. In this review article, we present the novel use of exogenous DNA repair enzymes and describe their role in combating photocarcinogenesis and photoaging. Topical application of these enzymes serves to supplement intrinsic DNA repair mechanisms. The direct repair of DNA damage by endogenous repair enzymes lessens rates of mutagenesis and strengthens the immune response to tumor cells. However, these innate mechanisms are not 100% efficient. The use of exogenous DNA repair enzymes presents a novel way to supplement intrinsic mechanisms and improve their efficacy. Several DNA repair enzymes critical to the prevention of cutaneous malignancies have been isolated and added to topical preparations designed for skin cancer prevention. These DNA repair enzymes maximize the rate of DNA repair and provide a more efficient response to carcinogenesis.

  12. Association of thymine glycol lesioned DNA with repair enzyme endonuclease III-molecular dynamics study

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    Pinak, Miroslav [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-07-01

    The 2 nanoseconds molecular dynamics (MD) simulation has been performed for the system consisting of repair enzyme and DNA 30-mer with native thymine at position 16 replaced by thymine glycol (TG) solvated in water environment. After 950 picoseconds of MD the enzyme and DNA associated together to form complex that lasted stable up to 2 ns when simulation was terminated. At the contact area of enzyme and DNA there is glutamic acid located as close as 1.6 A to the C3' atom of phosphodiester bond of TG. Initial B-DNA molecule was bent and kinked at the TG during MD. This distortion caused that phosphodiester bond was easier accessible by amino acids of enzyme. The negative value of electrostatic energy (-26 kcal/mol) discriminates TG from nearly neutral native thymine and contributes to the specific recognition of this lesion. Higher number of close water molecules at TG site before formation of complex (compared with other nucleotides) indicates that glycosyl bond of the lesion is easily approached by repair enzyme during scanning of DNA surface and suggests the importance of specific hydration at the lesion during recognition process. (author)

  13. Biochemical Characterization of Mycobacterium tuberculosis DNA Repair Enzymes – Nfo, XthA and Nei2

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    Sailau Abeldenov

    2014-01-01

    Full Text Available Introduction: Tuberculosis (TB is a human disease caused by Mycobacterium tuberculosis (Mtb. Treatment of TB requires long-term courses of multi-drug therapies to eliminate subpopulations of bacteria, which sometimes persist against antibiotics. Therefore, understanding of the mechanism of Mtb antibiotic-resistance is extremely important. During infection, Mtb overcomes a variety of body defense mechanisms, including treatment with the reactive species of oxygen and nitrogen. The bases in DNA molecule are susceptible to the damages caused by reactive forms of intermediate compounds of oxygen and nitrogen. Most of this damage is repaired by the base excision repair (BER pathway. In this study, we aimed to biochemically characterize three Mtb DNA repair enzymes of BER pathway. Methods: XthA, nfo, and nei genes were identified in mycobacteria by homology search of genomic sequences available in the GenBank database. We used standard methods of genetic engineering  to clone and sequence Mtb genes, which coded Nfo, XthA and Nei2 repair enzymes. The protein products of Mtb genes were expressed and purified in Escherichia coli using affinity tags. The enzymatic activity of purified Nfo, XthA, and Nei2 proteins were measured using radioactively labeled DNA substrates containing various modified residues. Results: The genes end (Rv0670, xthA (Rv0427c, and nei (Rv3297 were PCR amplified using genomic DNA of Mtb H37Rv with primers that contain specific restriction sites. The amplified products were inserted into pET28c(+ expression vector in such a way that the recombinant proteins contain C-terminal histidine tags. The plasmid constructs were verified by sequencing and then transformed into the Escherichia coli BL21 (DE3 strain. Purification of recombinant proteins was performed using Ni2+ ions immobilized affinity column, coupled with the fast performance liquid chromatography machine AKTA. Identification of the isolated proteins was performed by

  14. Novel mechanism of regulation of the DNA repair enzyme OGG1 in tuberin-deficient cells

    Science.gov (United States)

    Habib, Samy L.; Bhandari, Besant K.; Sadek, Nahed; Abboud-Werner, Sherry L.; Abboud, Hanna E.

    2010-01-01

    Tuberin (protein encodes by tuberous sclerosis complex 2, Tsc2) deficiency is associated with the decrease in the DNA repair enzyme 8-oxoG-DNA glycosylase (OGG1) in tumour kidney of tuberous sclerosis complex (TSC) patients. The purpose of this study was to elucidate the mechanisms by which tuberin regulates OGG1. The partial deficiency in tuberin expression that occurs in the renal proximal tubular cells and kidney cortex of the Eker rat is associated with decreased activator protein 4 (AP4) and OGG1 expression. A complete deficiency in tuberin is associated with loss of AP4 and OGG1 expression in kidney tumour from Eker rats and the accumulation of significant levels of 8-oxo-deoxyguanosine. Knockdown of tuberin expression in human renal epithelial cells (HEK293) with small interfering RNA (siRNA) also resulted in a marked decrease in the expression of AP4 and OGG1. In contrast, overexpression of tuberin in HEK293 cells increased the expression of AP4 and OGG1 proteins. Downregulation of AP4 expression using siRNA resulted in a significant decrease in the protein expression of OGG1. Immunoprecipitation studies show that AP4 is associated with tuberin in cells. Gel shift analysis and chromatin immunoprecipitation identified the transcription factor AP4 as a positive regulator of the OGG1 promoter. AP4 DNA-binding activity is significantly reduced in Tsc2−/− as compared with Tsc2+/+ cells. Transcriptional activity of the OGG1 promoter is also decreased in tuberin-null cells compared with wild-type cells. These data indicate a novel role for tuberin in the regulation of OGG1 through the transcription factor AP4. This regulation may be important in the pathogenesis of kidney tumours in patients with TSC disease. PMID:20837600

  15. Esterase catalysis of substrate vapour: enzyme activity occurs at very low hydration.

    Science.gov (United States)

    Lind, Penelope A; Daniel, Roy M; Monk, Colin; Dunn, Rachel V

    2004-10-01

    It has been generally accepted that enzyme activity requires a minimal hydration of about 0.2 g H2O g(-1) protein. This fits well with evidence that hydration above this level is associated with the onset of intramolecular motions. The influence of enzyme hydration on the hydrolysis of substrate by Candida rugosa Lipase B and pig liver esterase was investigated. Each enzyme was studied as a powder at various hydration levels, using vapour phase ethyl butyrate as substrate. This procedure allows the separation of those effects that are due to hydration from those arising from diffusional constraints. We found hydrolytic activity in both enzymes at all hydration levels above zero (between 0.054-0.47 and 0.029-0.60 g H2O g(-1) protein, respectively) that were investigated. The lowest hydration level investigated, hydrolysis of ethyl butyrate requires water as a second substrate, the absence of activity at zero hydration does not rule out the possibility of enzyme activity in the absence of water. These results suggest that the properties conferred on proteins by water, at least above 10% surface coverage (in this case corresponding to a hydration level of 0.03 g H2O g(-1) protein), are not a requirement for enzyme catalysis.

  16. DNA double strand break repair enzymes function at multiple steps in retroviral infection

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    Agematsu Kazunaga

    2009-12-01

    Full Text Available Abstract Background DNA double strand break (DSB repair enzymes are thought to be necessary for retroviral infection, especially for the post-integration repair and circularization of viral cDNA. However, the detailed roles of DSB repair enzymes in retroviral infection remain to be elucidated. Results A GFP reporter assay showed that the infectivity of an HIV-based vector decreased in ATM- and DNA-PKcs-deficient cells when compared with their complemented cells, while that of an MLV-based vector was diminished in Mre11- and DNA-PKcs-deficient cells. By using a method based on inverse- and Alu-PCR, we analyzed sequences around 3' HIV-1 integration sites in ATM-, Mre11- and NBS1- deficient cells. Increased abnormal junctions between the HIV-1 provirus and the host DNA were found in these mutant cell lines compared to the complemented cell lines and control MRC5SV cells. The abnormal junctions contained two types of insertions: 1 GT dinucleotides, which are normally removed by integrase during integration, and 2 inserted nucleotides of unknown origin. Artemis-deficient cells also showed such abnormalities. In Mre11-deficient cells, part of a primer binding site sequence was also detected. The 5' host-virus junctions in the mutant cells also contained these types of abnormal nucleotides. Moreover, the host-virus junctions of the MLV provirus showed similar abnormalities. These findings suggest that DSB repair enzymes play roles in the 3'-processing reaction and protection of the ends of viral DNA after reverse transcription. We also identified both 5' and 3' junctional sequences of the same provirus by inverse PCR and found that only the 3' junctions were abnormal with aberrant short repeats, indicating that the integration step was partially impaired in these cells. Furthermore, the conserved base preferences around HIV-1 integration sites were partially altered in ATM-deficient cells. Conclusions These results suggest that DSB repair enzymes are

  17. Effects of microinjected photoreactivating enzyme on thymine dimer removal and DNA repair synthesis in normal human and xeroderma pigmentosum fibroblasts

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    Roza, L.; Vermeulen, W.; Bergen Henegouwen, J.B.; Eker, A.P.; Jaspers, N.G.; Lohman, P.H.; Hoeijmakers, J.H. (TNO Medical Biological Laboratory, Rijswijk (Netherlands))

    1990-03-15

    UV-induced thymine dimers (10 J/m2 of UV-C) were assayed in normal human and xeroderma pigmentosum (XP) fibroblasts with a monoclonal antibody against these dimers and quantitative fluorescence microscopy. In repair-proficient cells dimer-specific immunofluorescence gradually decreased with time, reaching about 25% of the initial fluorescence after 27 h. Rapid disappearance of dimers was observed in cells which had been microinjected with yeast photoreactivating enzyme prior to UV irradiation. This photoreactivation (PHR) was light dependent and (virtually) complete within 15 min of PHR illumination. In general, PHR of dimers strongly reduces UV-induced unscheduled DNA synthesis (UDS). However, when PHR was applied immediately after UV irradiation, UDS remained unchanged initially; the decrease set in only after 30 min. When PHR was performed 2 h after UV exposure, UDS dropped without delay. An explanation for this difference is preferential removal of some type(s) of nondimer lesions, which is responsible for the PHR-resistant UDS immediately following UV irradiation. After the rapid removal of these photoproducts, the bulk of UDS is due to dimer repair. From the rapid effect of dimer removal by PHR on UDS it can be deduced that the excision of dimers up to the repair synthesis step takes considerably less than 30 min. Also in XP fibroblasts of various complementation groups the effect of PHR was investigated. The immunochemical dimer assay showed rapid PHR-dependent removal comparable to that in normal cells. However, the decrease of (residual) UDS due to PHR was absent (in XP-D) or much delayed (in XP-A and -E) compared to normal cells. This supports the idea that in these XP cells preferential repair of nondimer lesions does occur, but at a much lower rate.

  18. Yeast redoxyendonuclease, a DNA repair enzyme similar to Escherichia coli endonuclease III

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    Gossett, J.; Lee, K.; Cunningham, R.P.; Doetsch, P.W.

    1988-04-05

    A DNA repair endonuclease (redoxyendonuclease) was isolated from bakers' yeast (Saccharomyces cerevisiae). The enzyme has been purified by a series of column chromatography steps and cleaves OsO/sub 4/-damaged, double-stranded DNA at sites of thymine glycol and heavily UV-irradiated DNA at sites of cytosine, thymine, and guanine photoproducts. The base specificity and mechanism of phosphodiester bond cleavage for the yeast redoxyendonuclease appear to be identical with those of Escherichia coli endonuclease III when thymine glycol containing, end-labeled DNA fragments of defined sequence are employed as substrates. Yeast redoxyendonuclease has an apparent molecular size of 38,000-42,000 daltons and is active in the absence of divalent metal cations. The identification of such an enzyme in yeast may be of value in the elucidation of the biochemical basis for radiation sensitivity in certain yeast mutants.

  19. Primase-polymerases are a functionally diverse superfamily of replication and repair enzymes.

    Science.gov (United States)

    Guilliam, Thomas A; Keen, Benjamin A; Brissett, Nigel C; Doherty, Aidan J

    2015-08-18

    Until relatively recently, DNA primases were viewed simply as a class of proteins that synthesize short RNA primers requisite for the initiation of DNA replication. However, recent studies have shown that this perception of the limited activities associated with these diverse enzymes can no longer be justified. Numerous examples can now be cited demonstrating how the term 'DNA primase' only describes a very narrow subset of these nucleotidyltransferases, with the vast majority fulfilling multifunctional roles from DNA replication to damage tolerance and repair. This article focuses on the archaeo-eukaryotic primase (AEP) superfamily, drawing on recently characterized examples from all domains of life to highlight the functionally diverse pathways in which these enzymes are employed. The broad origins, functionalities and enzymatic capabilities of AEPs emphasizes their previous functional misannotation and supports the necessity for a reclassification of these enzymes under a category called primase-polymerases within the wider functional grouping of polymerases. Importantly, the repositioning of AEPs in this way better recognizes their broader roles in DNA metabolism and encourages the discovery of additional functions for these enzymes, aside from those highlighted here.

  20. 6-Hydroxydopamine-induced glutathione alteration occurs via glutathione enzyme system in primary cultured astrocytes

    Institute of Scientific and Technical Information of China (English)

    Ji ZHANG; Jun HU; Jian-hua DING; Hong-hong YAO; Gang HU

    2005-01-01

    Aim: To define the role of enzymes involved in glutathione metabolism in 6-hydroxydopamine (6-OHDA)-induced glutathione alteration in primary cultured astrocytes.Methods: Total glutathione (GSx) levels were determined using the modified enzymatic microtiter plate assay.The mRNA levels ofγ-glutamylcysteine synthetase (γGCS), γ-glutamyltransferase (γGT), glutathione peroxidase (GPx), GR (glutathione reductase), and glutathione transferases (GST) were determined using RT-PCR.γGT activity was determined using γGT assay kits.Results: In primary cultured astrocytes, 6-OHDA induced a significant elevation of cellular GSx levels after treatment for 24 h.However, the GSx levels decreased after 24 h and the values were even lower than the value in the control group without 6-OHDA at 48 h.RT-PCR data showed that the mRNA levels of γGCS, the ratelimiting enzyme of γ-L-glutamyl-L-cysteinylglycine (GSH) synthesis, were increased by 6-OHDA after treatment for 24 h and 48 h; the mRNA levels of GPx, GR, and GST did not alter in 6-OHDA-treated astrocytes after treatment for 24 h and 48 h; and 6-OHDA increased the mRNA levels and the activity of γGT after treatment for 48 h,which induced a decrease in GSx levels, despite the up-regulation of γGCS after exposure to 6-OHDA for 48 h.Conclusion: The change in γGCS correlated with the increase in GSH levels induced by 6-OHDA after treatment for 24 h.GSx levels decreased because of increased γGT mRNA levels and γGT activity induced by 6-OHDA after treatment for 48 h.

  1. Enzyme therapy of xeroderma pigmentosum: safety and efficacy testing of T4N5 liposome lotion containing a prokaryotic DNA repair enzyme.

    Science.gov (United States)

    Yarosh, D; Klein, J; Kibitel, J; Alas, L; O'Connor, A; Cummings, B; Grob, D; Gerstein, D; Gilchrest, B A; Ichihashi, M; Ogoshi, M; Ueda, M; Fernandez, V; Chadwick, C; Potten, C S; Proby, C M; Young, A R; Hawk, J L

    1996-06-01

    Xeroderma pigmentosum (XP) is a rare genetic disease in which patients are defective in DNA repair and are extremely sensitive to solar UV radiation exposure. A new treatment approach was tested in these patients, in which a prokaryotic DNA repair enzyme specific for UV-induced DNA damage was delivered into the skin by means of topically applied liposomes to supplement the deficient activity. Acute and chronic safety testing in both mice and humans showed neither adverse reactions nor significant changes in serum chemistry or in skin histology. The skin of XP patients treated with the DNA repair liposomes had fewer cyclobutylpyrimidine dimers in DNA and showed less erythema than did control sites. The results encourage further clinical testing of this new enzyme therapy approach.

  2. Islet expression of the DNA repair enzyme 8-oxoguanosine DNA glycosylase (Ogg1) in human type 2 diabetes

    OpenAIRE

    Yoon Kun-Ho; Wang-Rodriguez Jessica; Dib Sergio A.; Anachkov Kamen A; Tyrberg Björn; Levine Fred

    2002-01-01

    Abstract Background It has become increasingly clear that β-cell failure plays a critical role in the pathogenesis of type 2 diabetes. Free-radical mediated β-cell damage has been intensively studied in type 1 diabetes, but not in human type 2 diabetes. Therefore, we studied the protein expression of the DNA repair enzyme Ogg1 in pancreases from type 2 diabetics. Ogg1 was studied because it is the major enzyme involved in repairing 7,8-dihydro-8-oxoguanosine DNA adducts, a lesion previously o...

  3. Recombinational repair of radiation-induced double-strand breaks occurs in the absence of extensive resection

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    Westmoreland, James W.; Resnick, Michael A.

    2016-01-01

    Recombinational repair provides accurate chromosomal restitution after double-strand break (DSB) induction. While all DSB recombination repair models include 5′-3′ resection, there are no studies that directly assess the resection needed for repair between sister chromatids in G-2 arrested cells of random, radiation-induced ‘dirty’ DSBs. Using our Pulse Field Gel Electrophoresis-shift approach, we determined resection at IR-DSBs in WT and mutants lacking exonuclease1 or Sgs1 helicase. Lack of either reduced resection length by half, without decreased DSB repair or survival. In the exo1Δ sgs1Δ double mutant, resection was barely detectable, yet it only took an additional hour to achieve a level of repair comparable to WT and there was only a 2-fold dose-modifying effect on survival. Results with a Dnl4 deletion strain showed that remaining repair was not due to endjoining. Thus, similar to what has been shown for a single, clean HO-induced DSB, a severe reduction in resection tract length has only a modest effect on repair of multiple, dirty DSBs in G2-arrested cells. Significantly, this study provides the first opportunity to directly relate resection length at DSBs to the capability for global recombination repair between sister chromatids. PMID:26503252

  4. Rev1 is a base excision repair enzyme with 5′-deoxyribose phosphate lyase activity

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    Prasad, Rajendra; Poltoratsky, Vladimir; Hou, Esther W.; Wilson, Samuel H.

    2016-01-01

    Rev1 is a member of the Y-family of DNA polymerases and is known for its deoxycytidyl transferase activity that incorporates dCMP into DNA and its ability to function as a scaffold factor for other Y-family polymerases in translesion bypass events. Rev1 also is involved in mutagenic processes during somatic hypermutation of immunoglobulin genes. In light of the mutation pattern consistent with dCMP insertion observed earlier in mouse fibroblast cells treated with a base excision repair-inducing agent, we questioned whether Rev1 could also be involved in base excision repair (BER). Here, we uncovered a weak 5′-deoxyribose phosphate (5′-dRP) lyase activity in mouse Rev1 and demonstrated the enzyme can mediate BER in vitro. The full-length Rev1 protein and its catalytic core domain are similar in their ability to support BER in vitro. The dRP lyase activity in both of these proteins was confirmed by NaBH4 reduction of the Schiff base intermediate and kinetics studies. Limited proteolysis, mass spectrometry and deletion analysis localized the dRP lyase active site to the C-terminal segment of Rev1's catalytic core domain. These results suggest that Rev1 could serve as a backup polymerase in BER and could potentially contribute to AID-initiated antibody diversification through this activity. PMID:27683219

  5. Encounter and extrusion of an intrahelical lesion by a DNA repair enzyme

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    Qi, Yan; Spong, Marie C.; Nam, Kwangho; Banerjee, Anirban; Jiralerspong, Sao; Karplus, Martin; Verdine, Gregory L.; Harvard-Med; Harvard

    2010-01-12

    How living systems detect the presence of genotoxic damage embedded in a million-fold excess of undamaged DNA is an unresolved question in biology. Here we have captured and structurally elucidated a base-excision DNA repair enzyme, MutM, at the stage of initial encounter with a damaged nucleobase, 8-oxoguanine (oxoG), nested within a DNA duplex. Three structures of intrahelical oxoG-encounter complexes are compared with sequence-matched structures containing a normal G base in place of an oxoG lesion. Although the protein-DNA interfaces in the matched complexes differ by only two atoms - those that distinguish oxoG from G - their pronounced structural differences indicate that MutM can detect a lesion in DNA even at the earliest stages of encounter. All-atom computer simulations show the pathway by which encounter of the enzyme with the lesion causes extrusion from the DNA duplex, and they elucidate the critical free energy difference between oxoG and G along the extrusion pathway.

  6. Assessing PreCR™ repair enzymes for restoration of STR profiles from artificially degraded DNA for human identification.

    Science.gov (United States)

    Robertson, James M; Dineen, Shauna M; Scott, Kristina A; Lucyshyn, Jonathan; Saeed, Maria; Murphy, Devonie L; Schweighardt, Andrew J; Meiklejohn, Kelly A

    2014-09-01

    Forensic scientists have used several approaches to obtain short tandem repeat (STR) profiles from compromised DNA samples, including supplementing the polymerase chain reaction (PCR) with enhancers and using procedures yielding reduced-length amplicons. For degraded DNA, the peak intensities of the alleles separated by electrophoresis generally decrease as the length of the allele increases. When the intensities of the alleles decrease below an established threshold, they are described as drop-outs, thus contributing to a partial STR profile. This work assesses the use of repair enzymes to improve the STR profiles from artificially degraded DNA. The commercial PreCR™ repair kit of DNA repair enzymes was tested on both purified DNA and native DNA in body fluids exposed to oxidizing agents, hydrolytic conditions, ultraviolet (UV) and ionizing radiation, and desiccation. The strategy was to restrict the level of DNA damage to that which yields partial STR profiles in order to test for allele restoration as opposed to simple allele enhancement. Two protocols were investigated for allele restoration: a sequential protocol using the manufacturer's repair procedure and a modified protocol reportedly designed for optimal STR analysis of forensic samples. Allele restoration was obtained with both protocols, but the peak height appeared to be higher for the modified protocol (determined by Mann-Kendall Trend Test). The success of the approach using the PreCR™ repair enzymes was sporadic; it led to allele restoration as well as allele drop-out. Additionally, allele restoration with the PreCR™ enzymes was compared with restoration by alternative, but commonly implemented approaches using Restorase™, PCRBoost™, bovine serum albumin (BSA) and the Minifiler™ STR system. The alternative methods were also successful in improving the STR profile, but their success also depended on the quality of the template encountered. Our results indicate the PreCR™ repair kit may

  7. Quantum mechanics/molecular mechanics study on the oxygen binding and substrate hydroxylation step in AlkB repair enzymes.

    Science.gov (United States)

    Quesne, Matthew G; Latifi, Reza; Gonzalez-Ovalle, Luis E; Kumar, Devesh; de Visser, Sam P

    2014-01-07

    AlkB repair enzymes are important nonheme iron enzymes that catalyse the demethylation of alkylated DNA bases in humans, which is a vital reaction in the body that heals externally damaged DNA bases. Its mechanism is currently controversial and in order to resolve the catalytic mechanism of these enzymes, a quantum mechanics/molecular mechanics (QM/MM) study was performed on the demethylation of the N(1) -methyladenine fragment by AlkB repair enzymes. Firstly, the initial modelling identified the oxygen binding site of the enzyme. Secondly, the oxygen activation mechanism was investigated and a novel pathway was found, whereby the catalytically active iron(IV)-oxo intermediate in the catalytic cycle undergoes an initial isomerisation assisted by an Arg residue in the substrate binding pocket, which then brings the oxo group in close contact with the methyl group of the alkylated DNA base. This enables a subsequent rate-determining hydrogen-atom abstraction on competitive σ- and π-pathways on a quintet spin-state surface. These findings give evidence of different locations of the oxygen and substrate binding channels in the enzyme and the origin of the separation of the oxygen-bound intermediates in the catalytic cycle from substrate. Our studies are compared with small model complexes and the effect of protein and environment on the kinetics and mechanism is explained.

  8. Characteristics of soil enzymes and the dominant species of repair trees in the reclamation of coal mine area

    Institute of Scientific and Technical Information of China (English)

    Wen-Ying ZHANG; Duo-Xi YAO; Zhi-Guo ZHANG; Qing YANG; Kui ZHAO; Shi-Kai AN

    2013-01-01

    In order to study the soil enzyme content at the mine reclamation area and choose a tree species with superior restoration capabilities,this paper takes Huainan Datong Mine as the study area,and five different enzymes under nine tree species as the study subject.The different enzyme activity indexes were measured,and the correlation analysis and the principal component analysis (PCA) method were applied to evaluate and screen the tree species with advanced restoration.The results demonstrate that there are some correlations among the different soil enzymes,including some very significant positive correlations among urease,phosphatase,invertase and protease.The best species in terms of repair is privet,and the worst is Haitong.This study provides a scientific basis for the selection of restoration-capable tree species in the reclamation area of the coal mine.

  9. Current advances in DNA repair: regulation of enzymes and pathways involved in maintaining genomic stability.

    Science.gov (United States)

    Neher, Tracy M; Turchi, John J

    2011-06-15

    Novel discoveries in the DNA repair field have lead to continuous and rapid advancement of our understanding of not only DNA repair but also DNA replication and recombination. Research in the field transcends numerous areas of biology, biochemistry, physiology, and medicine, making significant connections across these broad areas of study. From early studies conducted in bacterial systems to current analyses in eukaryotic systems and human disease, the innovative research into the mechanisms of repair machines and the consequences of ineffective DNA repair has impacted a wide scientific community. This Forum contains a select mix of primary research articles in addition to a number of timely reviews covering a subset of DNA repair pathways where recent advances and novel discoveries are improving our understanding of DNA repair, its regulation, and implications to human disease.

  10. Presence of base excision repair enzymes in the wheat aleurone and their activation in cells undergoing programmed cell death.

    Science.gov (United States)

    Bissenbaev, Amangeldy K; Ishchenko, Alexander A; Taipakova, Sabira M; Saparbaev, Murat K

    2011-10-01

    Cereal aleurone cells are specialized endosperm cells that produce enzymes to hydrolyze the starchy endosperm during germination. Aleurone cells can undergo programmed cell death (PCD) when incubated in the presence of gibberellic acid (GA) in contrast to abscisic acid (ABA) which inhibits the process. The progression of PCD in aleurone layer cells of wheat grain is accompanied by an increase in deoxyribonuclease (DNase) activities and the internucleosomal degradation of nuclear DNA. Reactive oxygen species (ROS) are increased during PCD in the aleurone cells owing to the β-oxidation of triglycerides and inhibition of the antioxidant enzymes possibly leading to extensive oxidative damage to DNA. ROS generate mainly non-bulky DNA base lesions which are removed in the base excision repair (BER) pathway, initiated by the DNA glycosylases. At present, very little is known about oxidative DNA damage repair in cereals. Here, we study DNA repair in the cell-free extracts of wheat aleurone layer incubated or not with phytohormones. We show, for the first time, the presence of 8-oxoguanine-DNA and ethenoadenine-DNA glycosylase activities in wheat aleurone cells. Interestingly, the DNA glycosylase and AP endonuclease activities are strongly induced in the presence of GA. Based on these data we propose that GA in addition to activation of nuclear DNases also induces the DNA repair activities which remove oxidized DNA bases in the BER pathway. Potential roles of the wheat DNA glycosylases in GA-induced oligonucleosomal fragmentation of DNA and metabolic activation of aleurone layer cells via repair of transcribed regions are discussed.

  11. The Emerging Roles of ATP-Dependent Chromatin Remodeling Enzymes in Nucleotide Excision Repair

    Directory of Open Access Journals (Sweden)

    Wioletta Czaja

    2012-09-01

    Full Text Available DNA repair in eukaryotic cells takes place in the context of chromatin, where DNA, including damaged DNA, is tightly packed into nucleosomes and higher order chromatin structures. Chromatin intrinsically restricts accessibility of DNA repair proteins to the damaged DNA and impacts upon the overall rate of DNA repair. Chromatin is highly responsive to DNA damage and undergoes specific remodeling to facilitate DNA repair. How damaged DNA is accessed, repaired and restored to the original chromatin state, and how chromatin remodeling coordinates these processes in vivo, remains largely unknown. ATP-dependent chromatin remodelers (ACRs are the master regulators of chromatin structure and dynamics. Conserved from yeast to humans, ACRs utilize the energy of ATP to reorganize packing of chromatin and control DNA accessibility by sliding, ejecting or restructuring nucleosomes. Several studies have demonstrated that ATP-dependent remodeling activity of ACRs plays important roles in coordination of spatio-temporal steps of different DNA repair pathways in chromatin. This review focuses on the role of ACRs in regulation of various aspects of nucleotide excision repair (NER in the context of chromatin. We discuss current understanding of ATP-dependent chromatin remodeling by various subfamilies of remodelers and regulation of the NER pathway in vivo.

  12. Origin and evolution of the protein-repairing enzymes methionine sulphoxide reductases.

    Science.gov (United States)

    Zhang, Xing-Hai; Weissbach, Herbert

    2008-08-01

    The majority of extant life forms thrive in an O2-rich environment, which unavoidably induces the production of reactive oxygen species (ROS) during cellular activities. ROS readily oxidize methionine (Met) residues in proteins/peptides to form methionine sulphoxide [Met(O)] that can lead to impaired protein function. Two methionine sulphoxide reductases, MsrA and MsrB, catalyse the reduction of the S and R epimers, respectively, of Met(O) in proteins to Met. The Msr system has two known functions in protecting cells against oxidative damage. The first is to repair proteins that have lost activity due to Met oxidation and the second is to function as part of a scavenger system to remove ROS through the reversible oxidation/reduction of Met residues in proteins. Bacterial, plant and animal cells lacking MsrA are known to be more sensitive to oxidative stress. The Msr system is considered an important cellular defence mechanism to protect against oxidative stress and may be involved in ageing/senescence. MsrA is present in all known eukaryotes and eubacteria and a majority of archaea, reflecting its essential role in cellular life. MsrB is found in all eukaryotes and the majority of eubacteria and archaea but is absent in some eubacteria and archaea, which may imply a less important role of MsrB compared to MsrA. MsrA and MsrB share no sequence or structure homology, and therefore probably emerged as a result of independent evolutionary events. The fact that some archaea lack msr genes raises the question of how these archaea cope with oxidative damage to proteins and consequently of the significance of msr evolution in oxic eukaryotes dealing with oxidative stress. Our best hypothesis is that the presence of ROS-destroying enzymes such as peroxiredoxins and a lower dissolved O2 concentration in those msr-lacking organisms grown at high temperatures might account for the successful survival of these organisms under oxidative stress.

  13. [Photoreactivating Activity of Bioluminescence: Repair of UV-damaged DNA of Escherichia coli Occurs with Assistance of lux-Genes of Marine Bacteria].

    Science.gov (United States)

    Zavilgelsky, G B; Melkina, O E; Kotova, V Yu; Konopleva, M N; Manukhov, I V; Pustovoit, K Ss

    2015-01-01

    The UV resistance of luminescent bacteria Escherichia coli AB1886 uvrA6 (pLeo1) containing the plasmid with luxCDABE genes of marine bacteria Photobacterium leiognathi is approximately two times higher than the UV resistance of non-luminous bacteria E. coli AB1886 uvrA6. Introduction of phr::kan(r) mutations (a defect in the functional activity of photolyase) into the genome of E. coli AB1886 uvrA6 (pLeo1) completely removes the high UV resistance of the cells. Therefore, photoreactivation that involves bacterial photolyase contributes mainly to the bioluminescence-induced DNA repair. It is shown that photoreactivating activity of bioluminescence of P. leiognathi is about 2.5 times lower compared with that one induced by a light source with λ > 385 nm. It is also shown that an increase in the bioluminescence intensity, induced by UV radiation in E. coli bacterial cells with a plasmid containing the luxCD ABE genes under RecA-LexA-regulated promoters, occurs only 25-30 min later after UV irradiation of cells and does not contribute to DNA repair. A quorum sensing regulatory system is not involved in the DNA repair by photolyase.

  14. Salidroside stimulates DNA repair enzyme Parp-1 activity in mouse HSC maintenance.

    Science.gov (United States)

    Li, Xue; Sipple, Jared; Pang, Qishen; Du, Wei

    2012-05-03

    Salidroside is a phenylpropanoid glycoside isolated from the medicinal plant Rhodiola rosea, which has potent antioxidant properties. Here we show that salidroside prevented the loss of hematopoietic stem cells (HSCs) in mice under oxidative stress. Quiescent HSCs were recruited into cell cycling on in vivo challenge with oxidative stress, which was blocked by salidroside. Surprisingly, salidroside does not prevent the production of reactive oxygen species but reduces hydrogen peroxide-induced DNA-strand breaks in bone marrow cells enriched for HSCs. We tested whether salidroside enhances oxidative DNA damage repair in mice deficient for 5 DNA repair pathways known to be involved in oxidative DNA damage repair; we found that salidroside activated poly(ADP-ribose)polymerase-1 (PARP-1), a component of the base excision repair pathway, in mouse bone marrow HSCs as well as primary fibroblasts and human lymphoblasts. PARP-1 activation by salidroside protects quiescent HSCs from oxidative stress-induced cycling in native animals and self-renewal defect in transplanted recipients, which was abrogated by genetic ablation or pharmacologic inhibition of PARP-1. Together, these findings suggest that activation of PARP-1 by salidroside could affect the homeostasis and function of HSCs and contribute to the antioxidant effects of salidroside.

  15. Enzyme

    Science.gov (United States)

    Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For ... use them. Blood clotting is another example of enzymes at work. Enzymes are needed for all body ...

  16. Sublethal gamma irradiation affects reproductive impairment and elevates antioxidant enzyme and DNA repair activities in the monogonont rotifer Brachionus koreanus

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jeonghoon; Won, Eun-Ji [Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Il-Chan; Yim, Joung Han [Division of Life Sciences, Korea Polar Research Institute, Incheon 406-840 (Korea, Republic of); Lee, Su-Jae [Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Jae-Seong, E-mail: jslee2@skku.edu [Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-10-15

    Highlights: • No mortality within 96 h even at a high intensity (1200 Gy). • A reduced fecundity of Brachionus koreanus at over 150 Gy with a decrease in lifespan. • Dose-dependent ROS increase with GST enzyme activity at sub-lethal doses. • Significant impact on life table parameters, particularly fecundity. • Significant up-regulation of DNA repair-associated genes at sublethal doses. - Abstract: To examine the effects of gamma radiation on marine organisms, we irradiated several doses of gamma ray to the microzooplankton Brachionus koreanus, and measured in vivo and in vitro endpoints including the survival rate, lifespan, fecundity, population growth, gamma ray-induced oxidative stress, and modulated patterns of enzyme activities and gene expressions after DNA damage. After gamma radiation, no individuals showed any mortality within 96 h even at a high intensity (1200 Gy). However, a reduced fecundity (e.g. cumulated number of offspring) of B. koreanus at over 150 Gy was observed along with a slight decrease in lifespan. At 150 Gy and 200 Gy, the reduced fecundity of the rotifers led to a significant decrease in population growth, although in the second generation the population growth pattern was not affected even at 200 Gy when compared to the control group. At sub-lethal doses, reactive oxygen species (ROS) levels dose-dependently increased with GST enzyme activity. In addition, up-regulations of the antioxidant and chaperoning genes in response to gamma radiation were able to recover cellular damages, and life table parameters were significantly influenced, particularly with regard to fecundity. DNA repair-associated genes showed significantly up-regulated expression patterns in response to sublethal doses (150 and 200 Gy), as shown in the expression of the gamma-irradiated B. koreanus p53 gene, suggesting that these sublethal doses were not significantly fatal to B. koreanus but induced DNA damages leading to a decrease of the population size.

  17. Regulation of Ceramide Synthase-Mediated Crypt Epithelium Apoptosis by DNA Damage Repair Enzymes

    Science.gov (United States)

    Rotolo, Jimmy A.; Mesicek, Judith; Maj, Jerzy; Truman, Jean-Philip; Haimovitz-Friedman, Adriana; Kolesnick, Richard; Fuks, Zvi

    2015-01-01

    Acute endothelial cell apoptosis and microvascular compromise couple GI tract irradiation to reproductive death of intestinal crypt stem cell clonogens (SCCs) following high-dose radiation. Genetic or pharmacologic inhibition of endothelial apoptosis prevents intestinal damage, but as the radiation dose is escalated, SCCs become directly susceptible to an alternate cell death mechanism, mediated via ceramide synthase (CS)-stimulated de novo synthesis of the pro-apoptotic sphingolipid ceramide, and p53-independent apoptosis of crypt SCCs. We previously reported that ATM deficiency resets the primary radiation lethal pathway, allowing CS-mediated apoptosis at the low-dose range of radiation. The mechanism for this event, termed target reordering, remains unknown. Here we show that inactivation of DNA damage repair pathways signal CS-mediated apoptosis in crypt SCCs, presumably via persistent unrepaired DNA double strand breaks (DSBs). Genetic loss-of-function of sensors and transducers of DNA DSB repair confers the CS-mediated lethal pathway in intestines of sv129/B6Mre11ATLD1/ATLD1 and C57BL/6Prkdc/SCID (SCID) mice exposed to low-dose radiation. In contrast, CS-mediated SCC lethality was mitigated in irradiated gain-of-function Rad50S/S mice, and epistasis studies order Rad50 upstream of Mre11. These studies suggest unrepaired DNA DSBs as causative in target re-ordering in intestinal SCCs. As such, we provide an in vivo model of DNA damage repair that is standardized, can be exploited to understand allele-specific regulation in intact tissue, and is pharmacologically tractable. PMID:20086180

  18. Effects of naturally occurring dihydroflavonols from Inula viscosa on inflammation and enzymes involved in the arachidonic acid metabolism.

    Science.gov (United States)

    Hernández, Victoriano; Recio, M Carmen; Máñez, Salvador; Giner, Rosa M; Ríos, José-Luis

    2007-07-19

    The anti-inflammatory properties of three flavanones isolated from Inula viscosa, sakuranetin, 7-O-methylaromadendrin, and 3-acetyl-7-O-methylaromadendrin, have been tested both in vitro and in vivo. Acute inflammation in vivo was induced by means of topical application of 12-O-tetradecanoylphorbol 13-acetate (TPA) to mouse ears or by subcutaneous injection of phospholipase A(2) (PLA(2)) into mouse paws. The test compounds were evaluated in vitro for their effect on both the metabolism of arachidonic acid and on the release and/or activity of enzymes involved in the inflammatory response such as elastase, myeloperoxidase (MPO), and protein kinase C (PKC). The most active compounds in vivo against PLA(2)-induced paw oedema were 7-O-methylaromadendrin (ED(50)=8 mg/kg) and sakuranetin (ED(50)=18 mg/kg). In contrast, the most potent compound against TPA-induced ear oedema was 3-acetyl-7-O-methylaromadendrin (ED(50)=185 microg/ear), followed by sakuranetin (ED(50)=205 microg/ear). In vitro, the latter compound was the most potent inhibitor of leukotriene (LT) B(4) production by peritoneal rat neutrophils (IC(50)=9 microM) and it was also the only compound that directly inhibited the activity of 5-lipoxygenase (5-LOX). 3-Acetyl-7-O-methylaromadendrin also inhibited LTB(4) production (IC(50)=15 microM), but had no effect on 5-LOX activity. The only flavanone that inhibited the secretory PLA(2) activity in vitro was 7-O-methylaromadendrin. This finding may partly explain the anti-inflammatory effect observed in vivo, although other mechanisms such as the inhibition of histamine release by mast cells may also be implicated. Sakuranetin at 100 microM was found to inhibit elastase release, although this result is partly due to direct inhibition of the enzyme itself. At the same concentration, 7-O-methylaromadendrin only affected the enzyme release. Finally, none of the flavanones exhibited any effect on MPO or PKC activities. Taken together, these findings indicate that

  19. The Vsr endonuclease of Escherichia coli: an efficient DNA repair enzyme and a potent mutagen.

    Science.gov (United States)

    Macintyre, G; Doiron, K M; Cupples, C G

    1997-01-01

    The Vsr endonuclease of Escherichia coli initiates the repair of T/G mismatches caused by deamination of 5-methylcytosine to thymine. In this paper, we examine the capacity of Vsr to prevent CG-to-TA mutations in cells with increased transcription of the cytosine methylase gene (dcm). We find that sufficient Vsr is produced by a single chromosomal copy of vsr to prevent mutagenesis. We also investigate the cause of the transition and frameshift mutations in cells overproducing Vsr. Neither the absence of the dcm methylase nor its overproduction affects Vsr-stimulated mutagenesis. However, addition of mutS, mutL, or mutH on multicopy plasmids has a significant effect: mutL or mutH decreases the number of mutations, while mutS stimulates mutagenesis. The mut-containing plasmids have the same effect in cells treated with 2-aminopurine and in cells made defective in DNA proofreading, two experimental situations known to cause transition and frameshift mutations by saturating mismatch repair. PMID:9324251

  20. Head and neck squamous-cell cancer and its association with polymorphic enzymes of xenobiotic metabolism and repair.

    Science.gov (United States)

    Harth, Volker; Schafer, Martin; Abel, Josef; Maintz, Laura; Neuhaus, Thomas; Besuden, Mette; Primke, Robert; Wilkesmann, Anja; Thier, Ricarda; Vetter, Hans; Ko, Yon-Dschun; Bruning, Thomas; Bolt, Hermann M; Ickstadt, Katja

    2008-01-01

    Tobacco smoking, alcohol drinking, and occupational exposures to polycyclic aromatic hydrocarbons are the major proven risk factors for human head and neck squamous-cell cancer (HNSCC). Major research focus on gene-environment interactions concerning HNSCC has been on genes encoding enzymes of metabolism for tobacco smoke constituents and repair enzymes. To investigate the role of genetically determined individual predispositions in enzymes of xenobiotic metabolism and in repair enzymes under the exogenous risk factor tobacco smoke in the carcinogenesis of HNSCC, we conducted a case-control study on 312 cases and 300 noncancer controls. We focused on the impact of 22 sequence variations in CYP1A1, CYP1B1, CYP2E1, ERCC2/XPD, GSTM1, GSTP1, GSTT1, NAT2, NQO1, and XRCC1. To assess relevant main and interactive effects of polymorphic genes on the susceptibility to HNSCC we used statistical models such as logic regression and a Bayesian version of logic regression. In subgroup analysis of nonsmokers, main effects in ERCC2 (Lys751Gln) C/C genotype and combined ERCC2 (Arg156Arg) C/A and A/A genotypes were predominant. When stratifying for smokers, the data revealed main effects on combined CYP1B1 (Leu432Val) C/G and G/G genotypes, followed by CYP1B1 (Leu432Val) G/G genotype and CYP2E1 (-70G>T) G/T genotype. When fitting logistic regression models including relevant main effects and interactions in smokers, we found relevant associations of CYP1B1 (Leu432Val) C/G genotype and CYP2E1 (-70G>T) G/T genotype (OR, 10.84; 95% CI, 1.64-71.53) as well as CYP1B1 (Leu432Val) G/G genotype and GSTM1 null/null genotype (OR, 11.79; 95% CI, 2.18-63.77) with HNSCC. The findings underline the relevance of genotypes of polymorphic CYP1B1 combined with exposures to tobacco smoke.

  1. Islet expression of the DNA repair enzyme 8-oxoguanosine DNA glycosylase (Ogg1 in human type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Yoon Kun-Ho

    2002-04-01

    Full Text Available Abstract Background It has become increasingly clear that β-cell failure plays a critical role in the pathogenesis of type 2 diabetes. Free-radical mediated β-cell damage has been intensively studied in type 1 diabetes, but not in human type 2 diabetes. Therefore, we studied the protein expression of the DNA repair enzyme Ogg1 in pancreases from type 2 diabetics. Ogg1 was studied because it is the major enzyme involved in repairing 7,8-dihydro-8-oxoguanosine DNA adducts, a lesion previously observed in a rat model of type 2 diabetes. Moreover, in a gene expression screen, Ogg1 was over-expressed in islets from a human type 2 diabetic. Methods Immunofluorescent staining of Ogg1 was performed on pancreatic specimens from healthy controls and patients with diabetes for 2–23 years. The intensity and islet area stained for Ogg1 was evaluated by semi-quantitative scoring. Results Both the intensity and the area of islet Ogg1 staining were significantly increased in islets from the type 2 diabetic subjects compared to the healthy controls. A correlation between increased Ogg1 fluorescent staining intensity and duration of diabetes was also found. Most of the staining observed was cytoplasmic, suggesting that mitochondrial Ogg1 accounts primarily for the increased Ogg1 expression. Conclusion We conclude that oxidative stress related DNA damage may be a novel important factor in the pathogenesis of human type 2 diabetes. An increase of Ogg1 in islet cell mitochondria is consistent with a model in which hyperglycemia and consequent increased β-cell oxidative metabolism lead to DNA damage and the induction of Ogg1 expression.

  2. NAD(PH-hydrate dehydratase- a metabolic repair enzyme and its role in Bacillus subtilis stress adaptation.

    Directory of Open Access Journals (Sweden)

    Miroslava Petrovova

    Full Text Available BACKGROUND: One of the strategies for survival stress conditions in bacteria is a regulatory adaptive system called general stress response (GSR, which is dependent on the SigB transcription factor in Bacillus sp. The GSR is one of the largest regulon in Bacillus sp., including about 100 genes; however, most of the genes that show changes in expression during various stresses have not yet been characterized or assigned a biochemical function for the encoded proteins. Previously, we characterized the Bacillus subtilis168 osmosensitive mutant, defective in the yxkO gene (encoding a putative ribokinase, which was recently assigned in vitro as an ADP/ATP-dependent NAD(PH-hydrate dehydratase and was demonstrated to belong to the SigB operon. METHODS AND RESULTS: We show the impact of YxkO on the activity of SigB-dependent Pctc promoter and adaptation to osmotic and ethanol stress and potassium limitation respectively. Using a 2DE approach, we compare the proteomes of WT and mutant strains grown under conditions of osmotic and ethanol stress. Both stresses led to changes in the protein level of enzymes that are involved in motility (flagellin, citrate cycle (isocitrate dehydrogenase, malate dehydrogenase, glycolysis (phosphoglycerate kinase, and decomposition of Amadori products (fructosamine-6-phosphate deglycase. Glutamine synthetase revealed a different pattern after osmotic stress. The patterns of enzymes for branched amino acid metabolism and cell wall synthesis (L-alanine dehydrogenase, aspartate-semialdehyde dehydrogenase, ketol-acid reductoisomerase were altered after ethanol stress. CONCLUSION: We performed the first characterization of a Bacillus subtilis168 knock-out mutant in the yxkO gene that encodes a metabolite repair enzyme. We show that such enzymes could play a significant role in the survival of stressed cells.

  3. The relationship between microsomal enzyme induction and liver tumour formation : a study on the effects of xenobiotic and naturally occurring microsomal enzyme inducers on livers of male CF-1 mice

    NARCIS (Netherlands)

    Tennekes, H.A.

    1979-01-01

    The effects of naturally occurring microsomal enzyme inducers on important hepatocellular pathways for the metabolism of foreign compounds (xenobiotics) and also upon the incidence of liver tumours in CF-1 mice treated or not with 10 mg dieldrin.kg -1diet were inves

  4. The relationship between microsomal enzyme induction and liver tumour formation : a study on the effects of xenobiotic and naturally occurring microsomal enzyme inducers on livers of male CF-1 mice

    NARCIS (Netherlands)

    Tennekes, H.A.

    1979-01-01

    The effects of naturally occurring microsomal enzyme inducers on important hepatocellular pathways for the metabolism of foreign compounds (xenobiotics) and also upon the incidence of liver tumours in CF-1 mice treated or not with 10 mg dieldrin.kg

  5. Inactivation of the HR6B ubiquitin-conjugating DNA repair enzyme in mice causes male sterility associated with chromatin modification.

    NARCIS (Netherlands)

    J. van Klaveren; J. de Wit (Jan); C.G. van Gurp; M.H.M. Koken (Marcel); M. Vermey; J.H. van Roijen (Jan Herman); J.T.M. Vreeburg (Jan); W.M. Baarends (Willy); D. Bootsma (Dirk); J.A. Grootegoed (Anton); J.H.J. Hoeijmakers (Jan); H.P. Roest (Henk)

    1996-01-01

    textabstractThe ubiquitin-conjugating yeast enzyme RAD6 and its human homologs hHR6A and hHR6B are implicated in postreplication repair and damage-induced mutagenesis. The yeast protein is also required for sporulation and may modulate chromatin structure via histone ubiquitination. We report the ph

  6. Lack of the DNA repair enzyme OGG1 sensitizes dopamine neurons to manganese toxicity during development.

    Science.gov (United States)

    Cardozo-Pelaez, Fernando; Cox, David P; Bolin, Celeste

    2005-01-01

    Onset of Parkinson's disease (PD) and Parkinson-like syndromes has been associated with exposure to diverse environmental stimuli. Epidemiological studies have demonstrated that exposure to elevated levels of manganese produces neuropathological changes localized to the basal ganglia, including neuronal loss and depletions in striatal dopamine content. However, understanding the mechanisms associated with manganese neurotoxicity has been hampered by the lack of a good rodent model. Elevated levels of 8-hydroxy-2'-deoxyguanosine (oxo8dG) have been found in brain areas affected in PD. Whether increased DNA damage is responsible for neuronal degeneration or is a mere epiphenomena of neuronal loss remains to be elucidated. Thus, by using mice deficient in the ability to remove oxo8dG we aimed to determine if dysregulation of DNA repair coupled to manganese exposure would be detrimental to dopaminergic neurons. Wild-type and OGG1 knockout mice were exposed to manganese from conception to postnatal day 30; in both groups, exposure to manganese led to alterations in the neurochemistry of the nigrostriatal system. After exposure, dopamine levels were elevated in the caudate of wild-type mice. Dopamine was reduced in the caudate of OGG1 knockout mice, a loss that was paralleled by an increase in the dopamine index of turnover. In addition, the reduction of dopamine in caudate putamen correlated with the accumulation of oxo8dG in midbrain. We conclude that OGG1 function is essential in maintaining neuronal stability during development and identify DNA damage as a common pathway in neuronal loss after a toxicological challenge.

  7. Is engineering O{sub 2}-tolerant hydrogenases just a matter of reproducing the active sites of the naturally occurring O{sub 2}-resistant enzymes?

    Energy Technology Data Exchange (ETDEWEB)

    Leroux, Fanny; Liebgott, Pierre-Pol; Kpebe, Arlette; Leger, Christophe; Rousset, Marc; Dementin, Sebastien [CNRS, Laboratoire de Bioenergetique et Ingenierie des Proteines, Institut de Microbiologie de la Mediterranee, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Cournac, Laurent; Richaud, Pierre [CEA, DSV, IBEB, Laboratoire de Bioenergetique et Biotechnologie des Bacteries et Microalgues, 13108 Saint-Paul-lez-Durance (France); Aix-Marseille Universite, 3 place Victor-Hugo, 13331 Marseille (France); CNRS, UMR Biologie Vegetale et Microbiologie Environnementales, 13108 Saint-Paul-lez-Durance (France); Burlat, Benedicte; Guigliarelli, Bruno; Bertrand, Patrick [CNRS, Laboratoire de Bioenergetique et Ingenierie des Proteines, Institut de Microbiologie de la Mediterranee, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Aix-Marseille Universite, 3 place Victor-Hugo, 13331 Marseille (France)

    2010-10-15

    Reproducing the naturally occurring O{sub 2}-tolerant hydrogenases is a potential strategy to make the oxygen sensitive enzymes, produced by organisms of biotechnological interest, more resistant. The search for resistance ''hotspots'' that could be transposed into sensitive hydrogenases is underway. Here, we replaced two residues (Y77 and V78) of the oxygen sensitive [NiFe] hydrogenase from Desulfovibrio fructosovorans with Gly and with Cys, respectively, to copy the active site pocket of the resistant membrane-bound [NiFe] enzyme from Ralstonia eutropha and we examined how this affected oxygen sensitivity. The results are discussed in the light of a short review of the recent results dealing with the reactivity of hydrogenases towards oxygen. (author)

  8. Expression of DNA Repair Enzyme hMTH1 mRNA and Protein in Hepatocellular Carcinoma

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hejun; CHENG Bin; LIN Jusheng

    2005-01-01

    To study the expression of DNA repair enzyme hMTH1 mRNA and protein in hepatocellular carcinoma (HCC) tissues, tissues adjacent to the cancers, normal liver cells and hepatoma cell lines, and to investigate their function in the progress of HCC, semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) was employed to examine the expression of hMTH1 mRNA in matched HCC tissues (HT)/surrounding tissues (HST) of HCC, normal liver cell L02 and hepatoma cell lines SMMC7721, HepG2. hMTH1 protein was detected in corresponding HT as well as their HST by immunohistochemistry. Our results showed that the expression level of hMTH1 mRNA in HT was higher than that in HST (t=2.424, P <0.05). The expression level of hMTH1 mRNA in two hepatoma cell lines was higher than that in normal liver cell line (F=6.810, P <0.01). The expression of hMTH1 mRNA in SMMC7721 was similar to that in HepG2. hMTH1 protein was 88.2 % (15 of 17) positive in HT and 82.4 % (14 of 17) in HST. The protein level of hMTH1 in HT was correspondingly higher than in their HST (t=2.618,P<0.05). It is concluded that hMTH1 mRNA and protein were over-expressed in HCC and hepatoma cell lines. It may be one of the key events during the carcinogenesis,progression of HCC and may promote the malignant growth. These results suggest that hMTH1 plays a role in HCC and may be a candidate marker for the diagnosis of HCC.

  9. Inhibitory effects in the side reactions occurring during the enzymic synthesis of amoxicillin: p-hydroxyphenylglycine methyl ester and amoxicillin hydrolysis.

    Science.gov (United States)

    Gonçalves, Luciana R B; Fernandez-Lafuente, Roberto; Guisan, Jose M; Giordano, Raquel L C; Giordano, Roberto C

    2003-08-01

    Penicillin G acylase immobilized on glyoxyl-agarose is used to catalyse the reaction between p -hydroxyphenylglycine methyl ester (POHPGME) and 6-aminopenicillanic acid (6-APA). Inhibitory effects affecting the side reactions that occur during the synthesis of amoxicillin have been reported and need to be considered when proposing a kinetic model for the enzymic synthesis. In this work, we present a semi-empirical kinetic model that successively includes different inhibitory effects in the rate equations. The model performance was always compared with experimental data on amoxicillin synthesis. Enzyme load and stirring rate were chosen to prevent diffusional effects. Our results indicate that POHPGME and amoxicillin were competitive inhibitors of the hydrolysis of amoxicillin and POHPGME, respectively. 6-APA was a competitive inhibitor of the hydrolysis of amoxicillin. POHPG was a competitive inhibitor and methanol a non-competitive inhibitor of the hydrolysis of both ester and antibiotic, but the action of methanol was only noticeable at very high concentrations. Adding inhibitory effects to the kinetic model led to a significant increase in the accuracy of the simulations of the overall process of synthesis.

  10. Chemopreventive effects of diverse dietary phytochemicals against DMBA-induced hamster buccal pouch carcinogenesis via the induction of Nrf2-mediated cytoprotective antioxidant, detoxification, and DNA repair enzymes.

    Science.gov (United States)

    Kavitha, K; Thiyagarajan, P; Rathna Nandhini, J; Mishra, Rajakishore; Nagini, S

    2013-08-01

    Identifying agents that activate nuclear factor erythroid-2 related factor-2 (Nrf2), a key regulator of various cytoprotective antioxidant, and detoxifying enzymes has evolved as a promising strategy for cancer chemoprevention. In the present study, we investigated the effect of dietary supplementation of structurally diverse phytochemicals- astaxanthin, blueberry, chlorophyllin, ellagic acid, and theaphenon-E on Nrf2 signaling, and xenobiotic-metabolizing and antioxidant enzymes in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model. We observed that these phytochemicals induce nuclear accumulation of Nrf2 while downregulating its negative regulator, Keap-1. This was associated with reduced expression of CYP1A1 and CYP1B1, the cytochrome P450 isoforms involved in the activation of DMBA, and the oxidative stress marker 8-hydroxy-2'-deoxyguanosine coupled with upregulation of the phase II detoxification enzymes glutathione S-transferases and NAD(P)H:quinone oxidoreductase 1 and the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. In addition, these dietary phytochemicals also enhanced the DNA repair enzymes 8-oxoguanine glycosylase 1 (OGG1), xeroderma pigmentosum D (XPD), xeroderma pigmentosum G (XPG), and x-ray repair cross complementing group 1 (XRCC1). Our data provide substantial evidence that the dietary phytochemicals inhibit the development of HBP carcinomas through the activation of Nrf2/Keap-1 signaling and by upregulating cytoprotective enzymes. The extent of the chemopreventive effects of the phytochemicals was in the order: chlorophyllin > blueberry > ellagic acid > astaxanthin > theaphenon-E. Thus these dietary phytochemicals that function as potent activators of Nrf2 and its orchestrated response are novel candidates for cancer chemoprevention.

  11. CpG island hypermethylation of the DNA repair enzyme methyltransferase predicts response to temozolomide in primary gliomas.

    Science.gov (United States)

    Paz, Maria F; Yaya-Tur, Ricard; Rojas-Marcos, Iñigo; Reynes, Gaspar; Pollan, Marina; Aguirre-Cruz, Lucinda; García-Lopez, Jose Luis; Piquer, Jose; Safont, María-Jose; Balaña, Carmen; Sanchez-Cespedes, Montserrat; García-Villanueva, Mercedes; Arribas, Leoncio; Esteller, Manel

    2004-08-01

    The DNA repair enzyme O(6)-methylguanine DNA methyltransferase (MGMT) inhibits the killing of tumor cells by alkylating agents, and its loss in cancer cells is associated with hypermethylation of the MGMT CpG island. Thus, methylation of MGMT has been correlated with the clinical response to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in primary gliomas. Here, we investigate whether the presence of MGMT methylation in gliomas is also a good predictor of response to another emergent alkylating agent, temozolomide. Using a methylation-specific PCR approach, we assessed the methylation status of the CpG island of MGMT in 92 glioma patients who received temozolomide as first-line chemotherapy or as treatment for relapses. Methylation of the MGMT promoter positively correlated with the clinical response in the glioma patients receiving temozolomide as first-line chemotherapy (n = 40). Eight of 12 patients with MGMT-methylated tumors (66.7%) had a partial or complete response, compared with 7 of 28 patients with unmethylated tumors (25.0%; P = 0.030). We also found a positive association between MGMT methylation and clinical response in those patients receiving BCNU (n = 35, P = 0.041) or procarbazine/1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (n = 17, P = 0.043) as first-line chemotherapy. Overall, if we analyze the clinical response of all of the first-line chemotherapy treatments with temozolomide, BCNU, and procarbazine/1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea as a group in relation to the MGMT methylation status, MGMT hypermethylation was strongly associated with the presence of partial or complete clinical response (P < 0.001). Finally, the MGMT methylation status determined in the initial glioma tumor did not correlate with the clinical response to temozolomide when this drug was administered as treatment for relapses (P = 0.729). MGMT methylation predicts the clinical response of primary gliomas to first-line chemotherapy with the alkylating agent

  12. Expression of the Saccharomyces cerevisiae DNA repair gene RAD6 that encodes a ubiquitin conjugating enzyme, increases in response to DNA damage and in meiosis but remains constant during the mitotic cell cycle.

    Science.gov (United States)

    Madura, K; Prakash, S; Prakash, L

    1990-02-25

    The RAD6 gene of Saccharomyces cerevisiae encodes a ubiquitin-conjugating (E2) enzyme and is required for the repair of damaged DNA, mutagenesis, and sporulation. Here, we report our studies on the regulation of RAD6 gene expression after UV damage, during the mitotic cell cycle, in meiosis, and following heat shock and starvation. RAD6 mRNA levels became elevated in cells exposed to UV light, and at all UV doses the increase in mRNA levels was rapid and occurred within 30 min after exposure to UV. RAD6 mRNA levels also increased in sporulating MATa/MAT alpha cells, and the period of maximal accumulation of RAD6 mRNA during meiosis is coincident with the time during which recombination occurs. However, RAD6 mRNA levels showed no periodic fluctuation in the mitotic cell cycle, were not elevated upon heat shock, and fell in cells in the stationary phase of growth. These observations suggest that RAD6 activity is required throughout the cell cycle rather than being restricted to a specific stage, and that during meiosis, high levels of RAD6 activity may be needed at a stage coincident with genetic recombination. The observation that RAD6 transcription is not induced by heat and starvation, treatments that activate stress responses, suggests that the primary role of RAD6 is in the repair of damaged DNA rather than in adapting cells to stress situations.

  13. Archaeal DNA Polymerase-B as a DNA Template Guardian: Links between Polymerases and Base/Alternative Excision Repair Enzymes in Handling the Deaminated Bases Uracil and Hypoxanthine

    Directory of Open Access Journals (Sweden)

    Javier Abellón-Ruiz

    2016-01-01

    Full Text Available In Archaea repair of uracil and hypoxanthine, which arise by deamination of cytosine and adenine, respectively, is initiated by three enzymes: Uracil-DNA-glycosylase (UDG, which recognises uracil; Endonuclease V (EndoV, which recognises hypoxanthine; and Endonuclease Q (EndoQ, (which recognises both uracil and hypoxanthine. Two archaeal DNA polymerases, Pol-B and Pol-D, are inhibited by deaminated bases in template strands, a feature unique to this domain. Thus the three repair enzymes and the two polymerases show overlapping specificity for uracil and hypoxanthine. Here it is demonstrated that binding of Pol-D to primer-templates containing deaminated bases inhibits the activity of UDG, EndoV, and EndoQ. Similarly Pol-B almost completely turns off EndoQ, extending earlier work that demonstrated that Pol-B reduces catalysis by UDG and EndoV. Pol-B was observed to be a more potent inhibitor of the enzymes compared to Pol-D. Although Pol-D is directly inhibited by template strand uracil, the presence of Pol-B further suppresses any residual activity of Pol-D, to near-zero levels. The results are compatible with Pol-D acting as the replicative polymerase and Pol-B functioning primarily as a guardian preventing deaminated base-induced DNA mutations.

  14. Hypospadias repair

    Science.gov (United States)

    ... the problem. If the repair is not done, problems may occur later on such as: Difficulty controlling and directing urine stream A curve in the penis during erection Decreased fertility Embarrassment about appearance of penis Surgery ...

  15. UV radiation effects on a DNA repair enzyme: conversion of a [4Fe-4S](2+) cluster into a [2Fe-2S] (2+).

    Science.gov (United States)

    Folgosa, Filipe; Camacho, Inês; Penas, Daniela; Guilherme, Márcia; Fróis, João; Ribeiro, Paulo A; Tavares, Pedro; Pereira, Alice S

    2015-03-01

    Organisms are often exposed to different types of ionizing radiation that, directly or not, will promote damage to DNA molecules and/or other cellular structures. Because of that, organisms developed a wide range of response mechanisms to deal with these threats. Endonuclease III is one of the enzymes responsible to detect and repair oxidized pyrimidine base lesions. However, the effect of radiation on the structure/function of these enzymes is not clear yet. Here, we demonstrate the effect of UV-C radiation on E. coli endonuclease III through several techniques, namely UV-visible, fluorescence and Mössbauer spectroscopies, as well as SDS-PAGE and electrophoretic mobility shift assay. We demonstrate that irradiation with a UV-C source has dramatic consequences on the absorption, fluorescence, structure and functionality of the protein, affecting its [4Fe-4S] cluster and its DNA-binding ability, which results in its inactivation. An UV-C radiation-induced conversion of the [4Fe-4S](2+) into a [2Fe-2S](2+) was observed for the first time and proven by Mössbauer and UV-visible analysis. This work also shows that the DNA-binding capability of endonuclease III is highly dependent of the nuclearity of the endogenous iron-sulfur cluster. Thus, from our point of view, in a cellular context, these results strengthen the argument that cellular sensitivity to radiation can also be due to loss of radiation-induced damage repair ability.

  16. Effect of apelin on mitosis, apoptosis and DNA repair enzyme OGG 1/2 expression in intestinal cell lines IEC-6 and Caco-2.

    Science.gov (United States)

    Antushevich, Hanna; Krawczynska, Agata; Kapica, Malgorzata; Herman, Andrzej Przemyslaw; Zabielski, Romuald

    2014-01-01

    Apelin is a regulatory peptide, identified as an endogenous ligand of the Apelin receptor (APJ). Both the apelin and the APJ were detected in brain, lung, heart, mammary gland, kidney, placenta, adipose tissues and the gastrointestinal tract. Apelin is considered an important regulatory gut peptide with a potential physiological role in gastrointestinal cytoprotection, regulation of food intake and drinking behaviour. The aim of the present study was to assess the effect of the apelin on mitosis, apoptosis and the expression of DNA repair enzyme (OGG 1/2), and APJ receptor in intestinal cell lines: rat crypt (IEC-6) and human enterocyte model (Caco-2). The cell cultures were incubated with the apelin-12 (10-8 M) for 4, 6, 12, 24 and 48 h and the apoptosis (caspase 3), mitosis (Ki-67) and DNA repair enzyme (OGG1/2) markers were studied by Real-Time qRT-PCR and immunofluorescent methods. The results of Real-Time qRT-PCR and immunocytochemical analysis showed that the levels of mRNAs were inversely related to the expression level of corresponding proteins. Immunofluorescent studies revealed inhibitory effect of apelin-12 on apoptosis, mitosis and the expression of OGG1/2 in the intestinal crypt cell line IEC-6. However, in the enterocyte model Caco-2 cells apelin stimulated apoptosis and mitosis, and reduced OGG1/2 expression. These findings suggest that apelin may be involved in the control of epithelial cell turnover in the gastrointestinal tract.

  17. All three subunits of RecBCD enzyme are essential for DNA repair and low-temperature growth in the Antarctic Pseudomonas syringae Lz4W.

    Directory of Open Access Journals (Sweden)

    Theetha L Pavankumar

    Full Text Available BACKGROUND: The recD mutants of the Antarctic Pseudomonas syringae Lz4W are sensitive to DNA-damaging agents and fail to grow at 4 degrees C. Generally, RecD associates with two other proteins (RecB and RecC to produce RecBCD enzyme, which is involved in homologous recombination and DNA repair in many bacteria, including Escherichia coli. However, RecD is not essential for DNA repair, nor does its deletion cause any growth defects in E. coli. Hence, the assessment of the P. syringae RecBCD pathway was imperative. METHODOLOGY/PRINCIPAL FINDINGS: Mutational analysis and genetic complementation studies were used to establish that the individual null-mutations of all three genes, recC, recB, and recD, or the deletion of whole recCBD operon of P. syringae, lead to growth inhibition at low temperature, and sensitivity to UV and mitomycin C. Viability of the mutant cells dropped drastically at 4 degrees C, and the mutants accumulated linear chromosomal DNA and shorter DNA fragments in higher amounts compared to 22 degrees C. Additional genetic data using the mutant RecBCD enzymes that were inactivated either in the ATPase active site of RecB (RecB(K29Q or RecD (RecD(K229Q, or in the nuclease center of RecB (RecB(D1118A and RecB(Delta nuc suggested that, while the nuclease activity of RecB is not so critical in vivo, the ATP-dependent functions of both RecB and RecD are essential. Surprisingly, E. coli recBCD or recBC alone on plasmid could complement the defects of the Delta recCBD strain of P. syringae. CONCLUSIONS/SIGNIFICANCE: All three subunits of the RecBCD(Ps enzyme are essential for DNA repair and growth of P. syringae at low temperatures (4 degrees C. The RecD requirement is only a function of the RecBCD complex in the bacterium. The RecBCD pathway protects the Antarctic bacterium from cold-induced DNA damages, and is critically dependent on the helicase activities of both RecB and RecD subunits, but not on the nuclease of RecBCD(Ps enzyme.

  18. Endonuclease IV Is the Main Base Excision Repair Enzyme Involved in DNA Damage Induced by UVA Radiation and Stannous Chloride

    Directory of Open Access Journals (Sweden)

    Ellen S. Motta

    2010-01-01

    Full Text Available Stannous chloride (SnCl2 and UVA induce DNA lesions through ROS. The aim of this work was to study the toxicity induced by UVA preillumination, followed by SnCl2 treatment. E. coli BER mutants were used to identify genes which could play a role in DNA lesion repair generated by these agents. The survival assays showed (i The nfo mutant was the most sensitive to SnCl2; (ii lethal synergistic effect was observed after UVA pre-illumination, plus SnCl2 incubation, the nfo mutant being the most sensitive; (iii wild type and nfo mutants, transformed with pBW21 plasmid (nfo+ had their survival increased following treatments. The alkaline agarose gel electrophoresis assays pointed that (i UVA induced DNA breaks and fpg mutant was the most sensitive; (ii SnCl2-induced DNA strand breaks were higher than those from UVA and nfo mutant had the slowest repair kinetics; (iii UVA+SnCl2 promoted an increase in DNA breaks than SnCl2 and, again, nfo mutant displayed the slowest repair kinetics. In summary, Nfo protects E. coli cells against damage induced by SnCl2 and UVA+ SnCl2.

  19. Conserved structural chemistry for incision activity in structurally non-homologous apurinic/apyrimidinic endonuclease APE1 and endonuclease IV DNA repair enzymes.

    Energy Technology Data Exchange (ETDEWEB)

    Tsutakawa, Susan E.; Shin, David S.; Mol, Clifford D.; Izum, Tadahide; Arvai, Andrew S.; Mantha, Anil K.; Szczesny, Bartosz; Ivanov, Ivaylo N.; Hosfield, David J.; Maiti, Buddhadev; Pique, Mike E.; Frankel, Kenneth A.; Hitomi, Kenichi; Cunningham, Richard P.; Mitra, Sankar; Tainer, John A.

    2013-03-22

    Non-coding apurinic/apyrimidinic (AP) sites in DNA form spontaneously and as DNA base excision repair intermediates are the most common toxic and mutagenic in vivo DNA lesion. For repair, AP sites must be processed by 5' AP endonucleases in initial stages of base repair. Human APE1 and bacterial Nfo represent the two conserved 5' AP endonuclease families in the biosphere; they both recognize AP sites and incise the phosphodiester backbone 5' to the lesion, yet they lack similar structures and metal ion requirements. Here, we determined and analyzed crystal structures of a 2.4 ? resolution APE1-DNA product complex with Mg(2+) and a 0.92 Nfo with three metal ions. Structural and biochemical comparisons of these two evolutionarily distinct enzymes characterize key APE1 catalytic residues that are potentially functionally similar to Nfo active site components, as further tested and supported by computational analyses. We observe a magnesium-water cluster in the APE1 active site, with only Glu-96 forming the direct protein coordination to the Mg(2+). Despite differences in structure and metal requirements of APE1 and Nfo, comparison of their active site structures surprisingly reveals strong geometric conservation of the catalytic reaction, with APE1 catalytic side chains positioned analogously to Nfo metal positions, suggesting surprising functional equivalence between Nfo metal ions and APE1 residues. The finding that APE1 residues are positioned to substitute for Nfo metal ions is supported by the impact of mutations on activity. Collectively, the results illuminate the activities of residues, metal ions, and active site features for abasic site endonucleases.

  20. Influence of fatty acid synthase inhibitor orlistat on the DNA repair enzyme O6-methylguanine-DNA methyltransferase in human normal or malignant cells in vitro.

    Science.gov (United States)

    Cioccoloni, Giorgia; Bonmassar, Laura; Pagani, Elena; Caporali, Simona; Fuggetta, Maria Pia; Bonmassar, Enzo; D'Atri, Stefania; Aquino, Angelo

    2015-08-01

    Tetrahydrolipstatin (orlistat), an inhibitor of lipases and fatty acid synthase, is used orally for long-term treatment of obesity. Although the drug possesses striking antitumor activities in vitro against human cancer cells and in vitro and in vivo against animal tumors, it also induces precancerous lesions in rat colon. Therefore, we tested the in vitro effect of orlistat on the expression of O6-methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme that plays an essential role in the control of mutagenesis and carcinogenesis. Western blot analysis demonstrated that 2-day continuous exposure to 40 µM orlistat did not affect MGMT levels in a human melanoma cell line, but downregulated the repair protein by 30-70% in human peripheral blood mononuclear cells, in two leukemia and two colon cancer cell lines. On the other hand, orlistat did not alter noticeably MGMT mRNA expression. Differently from lomeguatrib (a false substrate, strong inhibitor of MGMT) orlistat did not reduce substantially MGMT function after 2-h exposure of target cells to the agent, suggesting that this drug is not a competitive inhibitor of the repair protein. Combined treatment with orlistat and lomeguatrib showed additive reduction of MGMT levels. More importantly, orlistat-mediated downregulation of MGMT protein expression was markedly amplified when the drug was combined with a DNA methylating agent endowed with carcinogenic properties such as temozolomide. In conclusion, even if orlistat is scarcely absorbed by oral route, it is possible that this drug could reduce local MGMT-mediated protection against DNA damage provoked by DNA methylating compounds on gastrointestinal tract epithelial cells, thus favoring chemical carcinogenesis.

  1. Rational Inhibitors of DNA Base Excision Repair Enzymes: New Tools for Elucidating the Role of BER in Cancer Chemotherapy. Addendum

    Science.gov (United States)

    2006-11-01

    PROCEDURES2 Materials. The 2′-deoxynucleoside phosphoramidites, CPG supports, and DNA synthesis reagents were purchased from Glen Research (Sterling, VA...flipping enzymes (28). EXPERIMENTAL PROCEDURES Materials. The 2′-deoxynucleoside phosphoramidites, CPG supports, and DNA synthesis reagents were...28425. (21) Klarmann, G. J.; Chen, X.; North, T. W.; Preston, B. D. J. Biol. Chem. 2003, 278, 7902- 7909 . (22) Mansky, L. M.; Preveral, S.; Selig, L

  2. The long N-terminus of the C. elegans DNA repair enzyme APN-1 targets the protein to the nucleus of a heterologous system.

    Science.gov (United States)

    Wang, Zhiqiang; Yang, Xiaoming; Mazouzi, Abdelghani; Ramotar, Dindial

    2014-12-15

    We previously isolated from a Caenorhabditis elegans cDNA library, designed for two-hybrid screening, a gene encoding the DNA repair enzyme APN-1 using cross-specie complementation analysis of the Saccharomyces cerevisiae apn1∆ apn2∆ tpp1∆ triple mutant deficient in the ability to repair several types of DNA lesions including apurinic/apyrimidinic (AP) sites. We subsequently purified the APN-1 from this yeast mutant and demonstrated that it possesses four distinct DNA repair activities. However, following the re-annotation of the C. elegans genome we discovered that the functionally active APN-1 encoded by the cDNA from the library might lack 108 amino acid residues from the N-terminus. We therefore synthesized the entire C. elegans apn-1 gene encoding the putative full-length APN-1 and created several N-terminal deletion mutants lacking either 63, 83 or 118 amino acid residues. The full-length APN-1, APN-1 (1-63Δ) and APN-1 (1-83Δ), but not APN-1 (1-118Δ) were stably expressed in the yeast triple mutant and cleaved the AP site substrate. However, only the full-length APN-1 rescued the yeast mutant from the genotoxicity caused by methyl methane sulfonate, a DNA damaging agent that creates AP sites in the genome. The full-length APN-1 was localized to the yeast nucleus, while APN-1 (1-63Δ) and APN-1 (1-83Δ) retained a cytoplasmic distribution. Our data suggest that the N-terminal region has no direct role in the DNA repair functions of APN-1 other than to target the protein to the nucleus and possibly to maintain its stability. Thus, the truncated APN-1, previously isolated from the two-hybrid library, ability to complement the yeast triple mutant depends on the engineered SV40 nuclear localization signal. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Combustion products of 1,3-butadiene inhibit catalase activity and induce expression of oxidative DNA damage repair enzymes in human bronchial epithelial cells.

    Science.gov (United States)

    Kennedy, Christopher H; Catallo, W James; Wilson, Vincent L; Mitchell, James B

    2009-10-01

    1,3-Butadiene, an important petrochemical, is commonly burned off when excess amounts need to be destroyed. This combustion process produces butadiene soot (BDS), which is composed of a complex mixture of polycyclic aromatic hydrocarbons in particulates ranging in size from DNA damage in NHBE cells. Thus, our aims were to determine the effect of butadiene soot ethanol extract (BSEE) on both enzyme activity and the expression of proteins involved in the repair of oxidative DNA damage. Catalase was found to be sensitive to BDS as catalase activity was potently diminished in the presence of BSEE. Using Western analysis, both the alpha isoform of human 8-oxoguanine DNA glycosylase (alpha-hOGG1) and human apurinic/apyrimidinic endonuclease (APE-1) were shown to be significantly overexpressed as compared to untreated controls after exposure of NHBE cells to BSEE. Our results indicate that BSEE is capable of effectively inactivating the antioxidant enzyme catalase, presumably via oxidation of protein amino acids. The presence of oxidized biomolecules may partially explain the extranuclear fluorescence that is detected when NHBE cells are treated with an organic extract of BDS. Overexpression of both alpha-hOGG1 and APE-1 proteins following treatment of NHBE cells with BSEE suggests that this mixture causes oxidative DNA damage.

  4. UV-induced DNA incision and proliferating cell nuclear antigen recruitment to repair sites occur independently of p53-replication protein A interaction in p53 wild type and mutant ovarian carcinoma cells

    NARCIS (Netherlands)

    Riva, F.; Zuco, V.; Vink, A.A.; Supino, R.; Prosperi, E.

    2001-01-01

    The tumour suppressor gene TP53 plays an important role in the regulation of DNA repair, and particularly of nucleotide excision repair. The influence of p53 status on the efficiency of the principal steps of this repair pathway was investigated after UV-C irradiation in the human ovarian carcinoma

  5. Biologic characteristic studies of DNA mismatch—repair enzyme hMSH2—deficient cell strain

    Institute of Scientific and Technical Information of China (English)

    HeY; ZhuaZX

    2002-01-01

    The effect of hMSH2 enzyme-deficiency on the cell growing phenotypes,cell ultrastructure,growth character and cell cycle were observed with electronic microscopy examination,cell counting and flow cytometry.hMSH2-deficient cell strain was constructed by transfecting hMSH2 recombination plasmid of antisense RNA into human embryo lung fibroblasts(HLF).In hMSH2-deficient cells,there were a lot of morphological changes under electronic microscopy,such as irregular shape,a lot of protuberances on the surface of cell,the enlarged nuclei.The average time of double increment of HLF and hMSH2-deficient cells were 1.0d and 0.78d,respectively.This suggested that the cell proliferation of hMSH2-deficient cells was greater than that of HLF.The distribution of HLF and hMSH2-deficient cells in G1,G2 and S phases was different.A large part of hMSH2-deficient cells was blocked in G1 phase.hMSH2-deficient cells increased,but it is still not a typical malignant cells.Thus,this cell strain could be used as biologic material to detect mutagenesis of environmental chemicals.

  6. When "Other" Initiate Repair.

    Science.gov (United States)

    Schegloff, Emanuel A.

    2000-01-01

    Elaborates on the locus of other-initiated repair, and reports on a number of environments in which others initiate repair turns later than the one directly following the trouble-source turn. Describes several ways that other initiation of repair, which occurs in next-turn position, may be delayed within that position. (Author/VWL)

  7. Optimality in DNA repair.

    Science.gov (United States)

    Richard, Morgiane; Fryett, Matthew; Miller, Samantha; Booth, Ian; Grebogi, Celso; Moura, Alessandro

    2012-01-07

    DNA within cells is subject to damage from various sources. Organisms have evolved a number of mechanisms to repair DNA damage. The activity of repair enzymes carries its own risk, however, because the repair of two nearby lesions may lead to the breakup of DNA and result in cell death. We propose a mathematical theory of the damage and repair process in the important scenario where lesions are caused in bursts. We use this model to show that there is an optimum level of repair enzymes within cells which optimises the cell's response to damage. This optimal level is explained as the best trade-off between fast repair and a low probability of causing double-stranded breaks. We derive our results analytically and test them using stochastic simulations, and compare our predictions with current biological knowledge.

  8. High altitude exposure alters gene expression levels of DNA repair enzymes, and modulates fatty acid metabolism by SIRT4 induction in human skeletal muscle.

    Science.gov (United States)

    Acs, Zoltan; Bori, Zoltan; Takeda, Masaki; Osvath, Peter; Berkes, Istvan; Taylor, Albert W; Yang, Hu; Radak, Zsolt

    2014-06-01

    We hypothesized that high altitude exposure and physical activity associated with the attack to Mt Everest could alter mRNA levels of DNA repair and metabolic enzymes and cause oxidative stress-related challenges in human skeletal muscle. Therefore, we have tested eight male mountaineers (25-40 years old) before and after five weeks of exposure to high altitude, which included attacks to peaks above 8000m. Data gained from biopsy samples from vastus lateralis revealed increased mRNA levels of both cytosolic and mitochondrial superoxide dismutase. On the other hand 8-oxoguanine DNA glycosylase (OGG1) mRNA levels tended to decrease while Ku70 mRNA levels and SIRT6 decreased with altitude exposure. The levels of SIRT1 and SIRT3 mRNA did not change significantly. However, SIRT4 mRNA level increased significantly, which could indicate decreases in fatty acid metabolism, since SIRT4 is one of the important regulators of this process. Within the limitations of this human study, data suggest that combined effects of high altitude exposure and physical activity climbing to Mt. Everest, could jeopardize the integrity of the particular chromosome. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. The DNA-mismatch repair enzyme hMSH2 modulates UV-B-induced cell cycle arrest and apoptosis in melanoma cells.

    Science.gov (United States)

    Seifert, Markus; Scherer, Stefan J; Edelmann, Wilfried; Böhm, Markus; Meineke, Viktor; Löbrich, Markus; Tilgen, Wolfgang; Reichrath, Jörg

    2008-01-01

    The mechanisms by which the post-replicative DNA mismatch repair (MMR) enzyme MSH2 is involved in the complex response mechanisms to UV damage are yet to be clarified. Here, we show increased levels of MSH2 mRNA in malignant melanoma, metastases of melanoma, and melanoma cell (MeWo) lines as compared with melanocytic nevi or primary cultured benign melanocytes. UV-B treatment modulated MSH2 expression and silencing of MSH2 gene expression using small interfering RNA technology regulated UV-B-induced cell cycle arrest and apoptosis in human MeWo. We show that MSH2-deficient non-malignant mouse fibroblasts (MEF-/-) are partially resistant against UV-B-induced apoptosis and show reduced S-Phase accumulation. In addition, we show that an Msh2 point mutation (MEFGA) that affects MMR does not affect UV-B-induced apoptosis. In conclusion, we demonstrate that MSH2 modulates in human melanocytes both UV-B-induced cell cycle regulation and apoptosis, most likely via independent, uncoupled mechanisms.

  10. The RSC and INO80 chromatin-remodeling complexes in DNA double-strand break repair.

    Science.gov (United States)

    Chambers, Anna L; Downs, Jessica A

    2012-01-01

    In eukaryotes, DNA is packaged into chromatin and is therefore relatively inaccessible to DNA repair enzymes. In order to perform efficient DNA repair, ATP-dependent chromatin-remodeling enzymes are required to alter the chromatin structure near the site of damage to facilitate processing and allow access to repair enzymes. Two of the best-studied remodeling complexes involved in repair are RSC (Remodels the Structure of Chromatin) and INO80 from Saccharomyces cerevisiae, which are both conserved in higher eukaryotes. RSC is very rapidly recruited to breaks and mobilizes nucleosomes to promote phosphorylation of H2A S129 and resection. INO80 enrichment at a break occurs later and is dependent on phospho-S129 H2A. INO80 activity at the break site also facilitates resection. Consequently, both homologous recombination and nonhomologous end-joining are defective in rsc mutants, while subsets of these repair pathways are affected in ino80 mutants.

  11. Preventive Long-Term Effects of a Topical Film-Forming Medical Device with Ultra-High UV Protection Filters and DNA Repair Enzyme in Xeroderma Pigmentosum: A Retrospective Study of Eight Cases

    Directory of Open Access Journals (Sweden)

    Sandra Giustini

    2014-09-01

    Full Text Available Skin cancer is common in xeroderma pigmentosum (XP due to a DNA repair mechanisms genetic defect. Ultraviolet (UV exposure is the main cause of increased incidence of actinic keratosis (AK, basal cell carcinoma (BCC and squamous cell carcinoma (SCC observed in XP subjects. Photoprotection is therefore a mandatory strategy in order to reduce skin damage. A topical DNA repair enzyme has been shown to slow down the development of skin lesions in XP. However, there are no data regarding the effects of photoprotection combined with DNA repair strategies in this clinical setting. A film-forming medical device containing the DNA repair enzyme photolyase and very high-protection UV filters (Eryfotona AK-NMSC, Ery is currently available. We report retrospective data regarding the use of Ery in 8 patients (5 women, 3 men with a diagnosis of XP treated for at least 12 consecutive months, comparing the rate of new skin lesions (AK, BCC and SCC during active treatment with Ery and during 12 months just before the use of the product. New AK, BCC and SCC mean lesion numbers during the 1-year Ery treatment were 5, 3 and 0, respectively in comparison with 14, 6.8 and 3 lesions, respectively during the 1-year pre-treatment period. Ery use was associated with a 65% reduction in appearance of new AK lesions and with 56 and 100% reductions in the incidence of new BCC and SCC lesions, respectively. These data suggest that topical use of photoprotection and DNA repair enzyme could help lower skin cancer lesions in XP. Control prospective trials are advisable in this clinical setting.

  12. Endogenous DNA Damage and Repair Enzymes-A short summary of the scientific achievements of Tomas Lindahl, Nobel Laureate in Chemistry 2015

    Institute of Scientific and Technical Information of China (English)

    Arne Klungland; Yun-Gui Yang

    2016-01-01

    Tomas Lindahl completed his medical studies at Karolinska Institute in 1970. Yet, his work has always been dedicated to unraveling fundamental mechanisms of DNA decay and DNA repair. His research is characterized with groundbreaking discoveries on the instability of our genome, the identification of novel DNA repair activities, the characterization of DNA repair pathways, and the association to diseases, throughout his 40 years of scientific career.

  13. Mitochondrial-targeted DNA repair enzyme 8-oxoguanine DNA glycosylase 1 protects against ventilator-induced lung injury in intact mice.

    Science.gov (United States)

    Hashizume, Masahiro; Mouner, Marc; Chouteau, Joshua M; Gorodnya, Olena M; Ruchko, Mykhaylo V; Potter, Barry J; Wilson, Glenn L; Gillespie, Mark N; Parker, James C

    2013-02-15

    This study tested the hypothesis that oxidative mitochondrial-targeted DNA (mtDNA) damage triggered ventilator-induced lung injury (VILI). Control mice and mice infused with a fusion protein targeting the DNA repair enzyme, 8-oxoguanine-DNA glycosylase 1 (OGG1) to mitochondria were mechanically ventilated with a range of peak inflation pressures (PIP) for specified durations. In minimal VILI (1 h at 40 cmH(2)O PIP), lung total extravascular albumin space increased 2.8-fold even though neither lung wet/dry (W/D) weight ratios nor bronchoalveolar lavage (BAL) macrophage inflammatory protein (MIP)-2 or IL-6 failed to differ from nonventilated or low PIP controls. This increase in albumin space was attenuated by OGG1. Moderately severe VILI (2 h at 40 cmH(2)O PIP) produced a 25-fold increase in total extravascular albumin space, a 60% increase in W/D weight ratio and marked increases in BAL MIP-2 and IL-6, accompanied by oxidative mitochondrial DNA damage, as well as decreases in the total tissue glutathione (GSH) and GSH/GSSH ratio compared with nonventilated lungs. All of these injury indices were attenuated in OGG1-treated mice. At the highest level of VILI (2 h at 50 cmH(2)O PIP), OGG1 failed to protect against massive lung edema and BAL cytokines or against depletion of the tissue GSH pool. Interestingly, whereas untreated mice died before completing the 2-h protocol, OGG1-treated mice lived for the duration of observation. Thus mitochondrially targeted OGG1 prevented VILI over a range of ventilation times and pressures and enhanced survival in the most severely injured group. These findings support the concept that oxidative mtDNA damage caused by high PIP triggers induction of acute lung inflammation and injury.

  14. Inguinal hernia repair - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100027.htm Inguinal hernia repair - series—Normal anatomy To use the sharing ... to slide 4 out of 4 Overview A hernia occurs when part of an organ protrudes through ...

  15. The journey of DNA repair

    OpenAIRE

    Saini, Natalie

    2015-01-01

    21 years ago, the DNA Repair Enzyme was declared “Molecule of the Year”. Today, we are celebrating another “year of repair”, with the 2015 Nobel Prize in Chemistry being awarded to Aziz Sancar, Tomas Lindahl and Paul Modrich for their collective work on the different DNA repair pathways.

  16. Inducible repair of oxidative DNA damage in Escherichia coli.

    Science.gov (United States)

    Demple, B; Halbrook, J

    Hydrogen peroxide is lethal to many cell types, including the bacterium Escherichia coli. Peroxides yield transient radical species that can damage DNA and cause mutations. Such partially reduced oxygen species are occasionally released during cellular respiration and are generated by lethal and mutagenic ionizing radiation. Because cells live in an environment where the threat of oxidative DNA damage is continual, cellular mechanisms may have evolved to avoid and repair this damage. Enzymes are known which evidently perform these functions. We report here that resistance to hydrogen peroxide toxicity can be induced in E. coli, that this novel induction is specific and occurs, in part, at the level of DNA repair.

  17. Rethinking transcription coupled DNA repair.

    Science.gov (United States)

    Kamarthapu, Venu; Nudler, Evgeny

    2015-04-01

    Nucleotide excision repair (NER) is an evolutionarily conserved, multistep process that can detect a wide variety of DNA lesions. Transcription coupled repair (TCR) is a subpathway of NER that repairs the transcribed DNA strand faster than the rest of the genome. RNA polymerase (RNAP) stalled at DNA lesions mediates the recruitment of NER enzymes to the damage site. In this review we focus on a newly identified bacterial TCR pathway in which the NER enzyme UvrD, in conjunction with NusA, plays a major role in initiating the repair process. We discuss the tradeoff between the new and conventional models of TCR, how and when each pathway operates to repair DNA damage, and the necessity of pervasive transcription in maintaining genome integrity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Expression of the ubiquitin-conjugating DNA repair enzymes HHR6A and B suggests a role in spermatogenesis and chromatin modification.

    NARCIS (Netherlands)

    M.H.M. Koken (Marcel); J.W. Hoogerbrugge (Jos); I. Jaspers-Dekker (Iris); J. de Wit (Jan); R. Willemsen (Rob); H.P. Roest (Henk); J.A. Grootegoed (Anton); J.H.J. Hoeijmakers (Jan)

    1996-01-01

    textabstractRAD6, a member of the expanding family of ubiquitin-conjugating (E2) enzymes, functions in the so-called "N-rule" protein breakdown pathway of Saccharomyces cerevisiae. In vitro, the protein can attach one or multiple ubiquitin (Ub) moieties to histones H2A and B and trigger their

  19. Effects of an Antimutagenic 1,4-Dihydropyridine AV-153 on Expression of Nitric Oxide Synthases and DNA Repair-related Enzymes and Genes in Kidneys of Rats with a Streptozotocin Model of Diabetes Mellitus.

    Science.gov (United States)

    Ošiņa, Kristīne; Rostoka, Evita; Isajevs, Sergejs; Sokolovska, Jelizaveta; Sjakste, Tatjana; Sjakste, Nikolajs

    2016-11-01

    Development of complications of diabetes mellitus (DM), including diabetic nephropathy, is a complex multi-stage process, dependent on many factors including the modification of nitric oxide (NO) production and an impaired DNA repair. The goal of this work was to study in vivo effects of 1,4-dihydropyridine AV-153, known as antimutagen and DNA binder, on the expression of several genes and proteins involved in NO metabolism and DNA repair in the kidneys of rats with a streptozotocin (STZ)-induced model of DM. Transcription intensity was monitored by means of real-time RT-PCR and the expression of proteins by immunohistochemistry. Development of DM significantly induced PARP1 protein expression, while AV-153 (0.5 mg/kg) administration decreased it. AV-153 increased the expression of Parp1 gene in the kidneys of both intact and diabetic animals. Expression of H2afx mRNA and γH2AX histone protein, a marker of DNA breakage, was not changed in diabetic animals, but AV-153 up-regulated the expression of the gene without any impact on the protein expression. Development of DM was followed by a significant increase in iNOS enzyme expression, while AV-153 down-regulated the enzyme expression up to normal levels. iNos gene expression was also found to be increased in diabetic animals, but unlike the protein, the expression of mRNA was found to be enhanced by AV-153 administration. Expression of both eNOS protein and eNos gene in the kidneys was down-regulated, and the administration of AV-153 normalized the expression level. The effects of the compound in the kidneys of diabetic animals appear to be beneficial, as a trend for the normalization of expression of NO synthases is observed. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  20. Tendon repair

    Science.gov (United States)

    Repair of tendon ... Tendon repair can be performed using: Local anesthesia (the immediate area of the surgery is pain-free) ... a cut on the skin over the injured tendon. The damaged or torn ends of the tendon ...

  1. Mechanisms of assembly of the enzyme-ssDNA complexes required for recombination-dependent DNA synthesis and repair in bacteriophage T4

    Energy Technology Data Exchange (ETDEWEB)

    Morrical, S.; Hempstead, K.; Morrical, M. [Univ. of Vermont College of Medicine, Burlington, VT (United States)

    1994-12-31

    During late stages of bacteriophage T4 infection in E. coli, the initiation of phage DNA replication is dependent on the homologous recombination activity of the T4 uvsX protein. In vitro, uvsX protein initiates DNA synthesis on a duplex template by inserting the 3{prime} end of a homologous ssDNA molecule into the duplex. The resulting D-loop structure serves as a primer-template junction for the assembly of the T4 replication fork. Two key steps in this initiation process are (A) the assembly of uvsX-ssDNA complexes necessary for recombination activity and for the priming of lead-strand DNA synthesis, and (B) the assembly of the T4 primosome (gp41 helicase/gp61 primase complex) onto the single-stranded template for lagging-strand synthesis. Our laboratory is focusing on the mechanisms of these two different but related enzyme-ssDNA assembly processes. In this extended abstract, we describe recent efforts in our laboratory to elucidate the mechanism by which the gp41 helicase enzyme is assembled onto gp32-covered ssDNA, a process requiring the activity of a special helicase assembly factor, the T4 gp59 protein.

  2. Bladder exstrophy repair

    Science.gov (United States)

    Bladder birth defect repair; Everted bladder repair; Exposed bladder repair; Repair of bladder exstrophy ... Bladder exstrophy repair involves two surgeries. The first surgery is to repair the bladder and the second one is to attach ...

  3. PCB126 enhanced the genotoxicity of BaP in HepG2 cells by modulating metabolic enzyme and DNA repair activities.

    Science.gov (United States)

    Wei, Wei; Zhang, Chi; Liu, Ai-Lin; Xie, Shao-Hua; Chen, Xue-Min; Lu, Wen-Qing

    2009-09-10

    Both of benzo(a)pyrene (BaP) and 3,3',4,4',5-pentachlorobiphenyl (PCB126) are ubiquitous and persistent environmental pollutants. These two chemicals coexist in various environmental media and human samples and thus may have combined effects on human health. However, the toxic effects and related mechanism of co-exposure to BaP and PCB126 remain unknown. In a series of experiments using the HepG2 cells exposed to BaP (50microM) or/and PCB126 (0.01, 0.1, 1 and 10nM), we measured the rate of micronucleus (MN) formation, CYP1A1 activity and expression of nucleotide excision repair (NER) proteins (XPA and XPC). We found that the exposure to BaP or PCB126 alone could effectively increase the CYP1A1 activity and the XPA expression. BaP alone had a profound enhancement of MN formation. Compared with BaP alone, co-exposure to both BaP and PCB126 significantly enhanced the CYP1A1 activity and the formation of MN but reduced the expression of both XPA and XPC. The synergistic effect of PCB126 on BaP-induced MN formation was inhibited by alpha-naphthoflavone (ANF), an inhibitor of CYP1A1. Our findings suggest that PCB126 may enhance BaP-induced DNA damage and genotoxicity by increasing cytochrome P450 1A activity and decreasing the NER capacity.

  4. An experimental double-blind irradiation study of a novel topical product (TPF 50) compared to other topical products with DNA repair enzymes, antioxidants, and growth factors with sunscreens: implications for preventing skin aging and cancer.

    Science.gov (United States)

    Emanuele, Enzo; Spencer, James M; Braun, Martin

    2014-03-01

    The exposure to ultraviolet radiation (UVR) is a major risk factor for skin aging and the development of non-melanoma skin cancer (NMSC). Although traditional sunscreens remain the mainstay for the prevention of UVR-induced skin damage, they cannot ensure a complete protection against the whole spectrum of molecular lesions associated with UVR exposure. The formation of helix-distorting photoproducts such as cyclobutane pyrimidine dimers (CPD), as well as oxidative damage to DNA bases, including the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8OHdG) are among the key DNA lesions associated with photoaging and tumorigenesis. Besides DNA lesions, UVR-induced formation of free radicals can result in protein carbonylation (PC), a major form of irreversible protein damage that inactivates their biological function. This study compares a complex novel topical product (TPF50) consisting of three actives, ie, 1) traditional physical sunscreens (SPF 50), 2) a liposome-encapsulated DNA repair enzymes complex (photolyase, endonuclease, and 8-oxoguanine glycosylase [OGG1]), and 3) a potent antioxidant complex (carnosine, arazine, ergothionine) to existing products. Specifically, we assessed the ability of TFP50 vs those of DNA repair and antioxidant and growth factor topical products used with SPF 50 sunscreens in preventing CPD, 8OHdG, and PC formation in human skin biopsies after experimental irradiations. In head-to-head comparison studies, TPF50 showed the best efficacy in reducing all of the three molecular markers. The results indicated that the three TPF50 components had a synergistic effect in reducing CPD and PC, but not 8OHdG. Taken together, our results indicate that TPF50 improves the genomic and proteomic integrity of skin cells after repeated exposure to UVR, ultimately reducing the risk of skin aging and NMSC.

  5. Starch Branching Enzyme 3 Occurs Within Starch Granules in Rice Endosperms%淀粉分支酶3存在于水稻胚乳的淀粉粒之中

    Institute of Scientific and Technical Information of China (English)

    佃蔚敏; 姜华武; 吴平

    2003-01-01

    对水稻胚乳淀粉颗粒结合的淀粉分支酶进行了研究.酶活性分析表明水稻胚乳中存在着与淀粉颗粒结合的淀粉分支酶.氨基酸测序分析结果表明结合于水稻胚乳淀粉粒的淀粉分支酶是分子量为84 kD的淀粉分支酶3(rice starch branching enzyme 3; RBE3).从开花后5 d到种子成熟,淀粉颗粒结合的RBE3蛋白都保持较为稳定的含量.Northern 分析表明水稻胚乳发育过程中RBE4最先表达而RBE3和RBE1的表达滞后.综合以上研究结果说明RBE3存在于水稻胚乳的淀粉之中是由于RBE3与淀粉葡聚糖链具有较高亲和性而难以和葡聚糖链解离,进而随着淀粉粒的增长而被其包裹.%The starch branching enzyme bound to starch granule in rice endosperm was investigated in the present paper. The starch branching enzyme activity assay indicated that some branching enzymes were bound to the starch granule of endosperm in rice. The result of N-terminal protein sequencing suggests that RBE3 (rice starch branching enzyme 3, RBE3), an 84 kD protein, bound to the starch granule of endosperm in rice. The level of starch granule-bound RBE3 protein remained approximately constant during the rice seed development. Northern blot analysis revealed that RBE4 was the earliest expressed starch branching enzyme during the development of rice endosperm and, subsequently RBE3 and RBE1 were expressed. These results suggest that RBE3 is bound to starch granule due to its high affinity to starch in rice endosperms.

  6. Envisioning the molecular choreography of DNA base excision repair.

    Science.gov (United States)

    Parikh, S S; Mol, C D; Hosfield, D J; Tainer, J A

    1999-02-01

    Recent breakthroughs integrate individual DNA repair enzyme structures, biochemistry and biology to outline the structural cell biology of the DNA base excision repair pathways that are essential to genome integrity. Thus, we are starting to envision how the actions, movements, steps, partners and timing of DNA repair enzymes, which together define their molecular choreography, are elegantly controlled by both the nature of the DNA damage and the structural chemistry of the participating enzymes and the DNA double helix.

  7. Epigenetic regulation of DNA repair machinery in Helicobacter pylori-induced gastric carcinogenesis.

    Science.gov (United States)

    Santos, Juliana Carvalho; Ribeiro, Marcelo Lima

    2015-08-14

    Although thousands of DNA damaging events occur in each cell every day, efficient DNA repair pathways have evolved to counteract them. The DNA repair machinery plays a key role in maintaining genomic stability by avoiding the maintenance of mutations. The DNA repair enzymes continuously monitor the chromosomes to correct any damage that is caused by exogenous and endogenous mutagens. If DNA damage in proliferating cells is not repaired because of an inadequate expression of DNA repair genes, it might increase the risk of cancer. In addition to mutations, which can be either inherited or somatically acquired, epigenetic silencing of DNA repair genes has been associated with carcinogenesis. Gastric cancer represents the second highest cause of cancer mortality worldwide. The disease develops from the accumulation of several genetic and epigenetic changes during the lifetime. Among the risk factors, Helicobacter pylori (H. pylori) infection is considered the main driving factor to gastric cancer development. Thus, in this review, we summarize the current knowledge of the role of H. pylori infection on the epigenetic regulation of DNA repair machinery in gastric carcinogenesis.

  8. Femoral hernia repair

    Science.gov (United States)

    Femorocele repair; Herniorrhaphy; Hernioplasty - femoral ... During surgery to repair the hernia, the bulging tissue is pushed back in. The weakened area is sewn closed or strengthened. This repair ...

  9. Undescended testicle repair

    Science.gov (United States)

    Orchidopexy; Inguinal orchidopexy; Orchiopexy; Repair of undescended testicle; Cryptorchidism repair ... first year of life without treatment. Undescended testicle repair surgery is recommended for patients whose testicles do ...

  10. Intestinal obstruction repair

    Science.gov (United States)

    Repair of volvulus; Intestinal volvulus - repair; Bowel obstruction - repair ... Intestinal obstruction repair is done while you are under general anesthesia . This means you are asleep and DO NOT feel pain. ...

  11. Aortic aneurysm repair - endovascular

    Science.gov (United States)

    EVAR; Endovascular aneurysm repair - aorta; AAA repair - endovascular; Repair - aortic aneurysm - endovascular ... Endovascular aortic repair is done because your aneurysm is very large, growing quickly, or is leaking or bleeding. You may have ...

  12. Motorcycle Repair.

    Science.gov (United States)

    Hein, Jim; Bundy, Mike

    This motorcycle repair curriculum guide contains the following ten areas of study: brake systems, clutches, constant mesh transmissions, final drives, suspension, mechanical starting mechanisms, electrical systems, fuel systems, lubrication systems, and overhead camshafts. Each area consists of one or more units of instruction. Each instructional…

  13. Turbine repair process, repaired coating, and repaired turbine component

    Energy Technology Data Exchange (ETDEWEB)

    Das, Rupak; Delvaux, John McConnell; Garcia-Crespo, Andres Jose

    2015-11-03

    A turbine repair process, a repaired coating, and a repaired turbine component are disclosed. The turbine repair process includes providing a turbine component having a higher-pressure region and a lower-pressure region, introducing particles into the higher-pressure region, and at least partially repairing an opening between the higher-pressure region and the lower-pressure region with at least one of the particles to form a repaired turbine component. The repaired coating includes a silicon material, a ceramic matrix composite material, and a repaired region having the silicon material deposited on and surrounded by the ceramic matrix composite material. The repaired turbine component a ceramic matrix composite layer and a repaired region having silicon material deposited on and surrounded by the ceramic matrix composite material.

  14. Pectic enzymes

    NARCIS (Netherlands)

    Benen, J.A.E.; Voragen, A.G.J.; Visser, J.

    2003-01-01

    The pectic enzymes comprise a diverse group of enzymes. They consist of main-chain depolymerases and esterases active on methyl- and acetylesters of galacturonosyl uronic acid residues. The depolymerizing enzymes comprise hydrolases as wel as lyases

  15. Pectic enzymes

    NARCIS (Netherlands)

    Benen, J.A.E.; Voragen, A.G.J.; Visser, J.

    2003-01-01

    The pectic enzymes comprise a diverse group of enzymes. They consist of main-chain depolymerases and esterases active on methyl- and acetylesters of galacturonosyl uronic acid residues. The depolymerizing enzymes comprise hydrolases as wel as lyases

  16. Enzyme assays.

    Science.gov (United States)

    Reymond, Jean-Louis; Fluxà, Viviana S; Maillard, Noélie

    2009-01-07

    Enzyme assays are analytical tools to visualize enzyme activities. In recent years a large variety of enzyme assays have been developed to assist the discovery and optimization of industrial enzymes, in particular for "white biotechnology" where selective enzymes are used with great success for economically viable, mild and environmentally benign production processes. The present article highlights the aspects of fluorogenic and chromogenic substrates, sensors, and enzyme fingerprinting, which are our particular areas of interest.

  17. Diversity of Endonuclease V: From DNA Repair to RNA Editing

    Directory of Open Access Journals (Sweden)

    Isao Kuraoka

    2015-09-01

    Full Text Available Deamination of adenine occurs in DNA, RNA, and their precursors via a hydrolytic reaction and a nitrosative reaction. The generated deaminated products are potentially mutagenic because of their structural similarity to natural bases, which in turn leads to erroneous nucleotide pairing and subsequent disruption of cellular metabolism. Incorporation of deaminated precursors into the nucleic acid strand occurs during nucleotide synthesis by DNA and RNA polymerases or base modification by DNA- and/or RNA-editing enzymes during cellular functions. In such cases, removal of deaminated products from DNA and RNA by a nuclease might be required depending on the cellular function. One such enzyme, endonuclease V, recognizes deoxyinosine and cleaves 3' end of the damaged base in double-stranded DNA through an alternative excision repair mechanism in Escherichia coli, whereas in Homo sapiens, it recognizes and cleaves inosine in single-stranded RNA. However, to explore the role of endonuclease V in vivo, a detailed analysis of cell biology is required. Based on recent reports and developments on endonuclease V, we discuss the potential functions of endonuclease V in DNA repair and RNA metabolism.

  18. Eye muscle repair - discharge

    Science.gov (United States)

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  19. Ventral hernia repair

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/007661.htm Ventral hernia repair To use the sharing features on this page, please enable JavaScript. Ventral hernia repair is surgery to repair a ventral hernia. ...

  20. Brain aneurysm repair

    Science.gov (United States)

    ... aneurysm repair; Dissecting aneurysm repair; Endovascular aneurysm repair - brain; Subarachnoid hemorrhage - aneurysm ... Your scalp, skull, and the coverings of the brain are opened. A metal clip is placed at ...

  1. Choreography of oxidative damage repair in mammalian genomes.

    Science.gov (United States)

    Mitra, Sankar; Izumi, Tadahide; Boldogh, Istvan; Bhakat, Kishor K; Hill, Jeff W; Hazra, Tapas K

    2002-07-01

    The lesions induced by reactive oxygen species in both nuclear and mitochondrial genomes include altered bases, abasic (AP) sites, and single-strand breaks, all repaired primarily via the base excision repair (BER) pathway. Although the basic BER process (consisting of five sequential steps) could be reconstituted in vitro with only four enzymes, it is now evident that repair of oxidative damage, at least in mammalian cell nuclei, is more complex, and involves a number of additional proteins, including transcription- and replication-associated factors. These proteins may be required in sequential repair steps in concert with other cellular changes, starting with nuclear targeting of the early repair enzymes in response to oxidative stress, facilitation of lesion recognition, and access by chromatin unfolding via histone acetylation, and formation of metastable complexes of repair enzymes and other accessory proteins. Distinct, specific subclasses of protein complexes may be formed for repair of oxidative lesions in the nucleus in transcribed vs. nontranscribed sequences in chromatin, in quiescent vs. cycling cells, and in nascent vs. parental DNA strands in replicating cells. Characterizing the proteins for each repair subpathway, their signaling-dependent modifications and interactions in the nuclear as well as mitochondrial repair complexes, will be a major focus of future research in oxidative damage repair.

  2. Bueno y la autorreparacion ("Bueno" and Conversational Self Repairs).

    Science.gov (United States)

    Carranza, Isolda

    The paper discusses the Spanish expression "bueno," which marks the beginning or the end of background and assertion self-repairs in conversation, and often co-occurs with other expressions, such as "viste" and "no?" which mark the other end of the repair. Background repairs provide information the speaker considers necessary for the hearer to…

  3. Chronic pain after inguinal hernia repair

    OpenAIRE

    2008-01-01

    : BACKGROUND: Chronic post herniorrhaphy groin pain is defined as pain lasting > 6 months after surgery, which is one of the most important complication occurring after inguinal hernia repair, occurs with greater frequency than previously thought. Chronic groin pain is one of the most significant complications following inguinal hernia repair, and majority of chronic pain has been attributed to ilioinguinal nerve entrapment. Various other factors are involved in development of...

  4. Failure strengths of repair devices versus meniscus suturing techniques

    OpenAIRE

    Asik, Mehmet; Sener, Nadir; Dikici, Fatih; Sen, Cengiz

    2004-01-01

    Objectives: The purpose of this study was to compare the load to failure of different common suturing techniques with that of repair devices. Methods: Seventy-one calf medial menisci were cut to simulate peripheral longitudinal tears and repaired using either one of the two suture techniques or one of the seven repair devices. Then the two parts of the meniscus were pulled using an Instron tensometer until failure occurred. The techniques and repair devices tested included vertical (0 PDS,...

  5. DNA repair. [UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Setlow, R.

    1978-01-01

    Some topics discussed are as follows: difficulty in extrapolating data from E. coli to mammalian systems; mutations caused by UV-induced changes in DNA; mutants deficient in excision repair; other postreplication mechanisms; kinds of excision repair systems; detection of repair by biochemical or biophysical means; human mutants deficient in repair; mutagenic effects of UV on XP cells; and detection of UV-repair defects among XP individuals. (HLW)

  6. Changes in DNA repair during aging

    Science.gov (United States)

    Gorbunova, Vera; Seluanov, Andrei; Mao, Zhiyong; Hine, Christpher

    2007-01-01

    DNA is a precious molecule. It encodes vital information about cellular content and function. There are only two copies of each chromosome in the cell, and once the sequence is lost no replacement is possible. The irreplaceable nature of the DNA sets it apart from other cellular molecules, and makes it a critical target for age-related deterioration. To prevent DNA damage cells have evolved elaborate DNA repair machinery. Paradoxically, DNA repair can itself be subject to age-related changes and deterioration. In this review we will discuss the changes in efficiency of mismatch repair (MMR), base excision repair (BER), nucleotide excision repair (NER) and double-strand break (DSB) repair systems during aging, and potential changes in DSB repair pathway usage that occur with age. Mutations in DNA repair genes and premature aging phenotypes they cause have been reviewed extensively elsewhere, therefore the focus of this review is on the comparison of DNA repair mechanisms in young versus old. PMID:17913742

  7. DNA repair genes in the Megavirales pangenome.

    Science.gov (United States)

    Blanc-Mathieu, Romain; Ogata, Hiroyuki

    2016-06-01

    The order 'Megavirales' represents a group of eukaryotic viruses with a large genome encoding a few hundred up to two thousand five hundred genes. Several members of Megavirales possess genes involved in major DNA repair pathways. Some of these genes were likely inherited from an ancient virus world and some others were derived from the genomes of their hosts. Here we examine molecular phylogenies of key DNA repair enzymes in light of recent hypotheses on the origin of Megavirales, and propose that the last common ancestors of the individual families of the order Megavirales already possessed DNA repair functions to achieve and maintain a moderately large genome and that this repair capacity gradually increased, in a family-dependent manner, during their recent evolution.

  8. Enzymes in Fermented Fish.

    Science.gov (United States)

    Giyatmi; Irianto, H E

    Fermented fish products are very popular particularly in Southeast Asian countries. These products have unique characteristics, especially in terms of aroma, flavor, and texture developing during fermentation process. Proteolytic enzymes have a main role in hydrolyzing protein into simpler compounds. Fermentation process of fish relies both on naturally occurring enzymes (in the muscle or the intestinal tract) as well as bacteria. Fermented fish products processed using the whole fish show a different characteristic compared to those prepared from headed and gutted fish. Endogenous enzymes like trypsin, chymotrypsin, elastase, and aminopeptidase are the most involved in the fermentation process. Muscle tissue enzymes like cathepsins, peptidases, transaminases, amidases, amino acid decarboxylases, glutamic dehydrogenases, and related enzymes may also play a role in fish fermentation. Due to the decreased bacterial number during fermentation, contribution of microbial enzymes to proteolysis may be expected prior to salting of fish. Commercial enzymes are supplemented during processing for specific purposes, such as quality improvement and process acceleration. In the case of fish sauce, efforts to accelerate fermentation process and to improve product quality have been studied by addition of enzymes such as papain, bromelain, trypsin, pepsin, and chymotrypsin. © 2017 Elsevier Inc. All rights reserved.

  9. The Role of Inducible DNA Repair in W-Reactivation and Related Phenomena.

    Science.gov (United States)

    1981-10-14

    sealing the backbone by a DNA ligase (Kushner et al. 1971) This "short-patch" excision repair eliminates photodimers by bacterial Uvr+ functions before DNA...Hart and Ellison 1970). W-reactivation of UV-irradiated phage X also occurs on E. coli with DNA ligase deficiency (Morse and Pauling 1975) or with the...arrest of DNA synthesis is essential for X induction. E. coli lig mutants produce defective DNA ligase , which is an enzyme that closes single-strand

  10. Pectus excavatum repair

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002949.htm Pectus excavatum repair To use the sharing features on this page, please enable JavaScript. Pectus excavatum repair is surgery to correct pectus excavatum . This ...

  11. Hand function after nerve repair.

    Science.gov (United States)

    Lundborg, G; Rosén, B

    2007-02-01

    Treatment of injuries to major nerve trunks in the hand and upper extremity remains a major and challenging reconstructive problem. Such injuries may cause long-lasting disabilities in terms of lost fine sensory and motor functions. Nowadays there is no surgical repair technique that can ensure recovery of tactile discrimination in the hand of an adult patient following nerve repair while very young individuals usually regain a complete recovery of functional sensibility. Post-traumatic nerve regeneration is a complex biological process where the outcome depends on multiple biological and environmental factors such as survival of nerve cells, axonal regeneration rate, extent of axonal misdirection, type of injury, type of nerve, level of the lesion, age of the patient and compliance to training. A major problem is the cortical functional reorganization of hand representation which occurs as a result of axonal misdirection. Although protective sensibility usually occurs following nerve repair, tactile discriminative functions seldom recover--a direct result of cortical remapping. Sensory re-education programmes are routinely applied to facilitate understanding of the new sensory patterns provided by the hand. New trends in hand rehabilitation focus on modulation of central nervous processes rather than peripheral factors. Principles are being evolved to maintain the cortical hand representation by using the brain capacity for visuo-tactile and audio-tactile interaction for the initial phase following nerve injury and repair (phase 1). After the start of the re-innervation of the hand (phase 2), selective de-afferentation, such as cutaneous anaesthesia of the forearm of the injured hand, allows expansion of the nerve-injured cortical hand representation, thereby enhancing the effects of sensory relearning. Recent data support the view that training protocols specifically addressing the relearning process substantially increase the possibilities for improved

  12. Hyperactivation of PARP triggers nonhomologous end-joining in repair-deficient mouse fibroblasts.

    Science.gov (United States)

    Gassman, Natalie R; Stefanick, Donna F; Kedar, Padmini S; Horton, Julie K; Wilson, Samuel H

    2012-01-01

    Regulation of poly(ADP-ribose) (PAR) synthesis and turnover is critical to determining cell fate after genotoxic stress. Hyperactivation of PAR synthesis by poly(ADP-ribose) polymerase-1 (PARP-1) occurs when cells deficient in DNA repair are exposed to genotoxic agents; however, the function of this hyperactivation has not been adequately explained. Here, we examine PAR synthesis in mouse fibroblasts deficient in the base excision repair enzyme DNA polymerase β (pol β). The extent and duration of PARP-1 activation was measured after exposure to either the DNA alkylating agent, methyl methanesulfonate (MMS), or to low energy laser-induced DNA damage. There was strong DNA damage-induced hyperactivation of PARP-1 in pol β nullcells, but not in wild-type cells. In the case of MMS treatment, PAR synthesis did not lead to cell death in the pol β null cells, but instead resulted in increased PARylation of the nonhomologous end-joining (NHEJ) protein Ku70 and increased association of Ku70 with PARP-1. Inhibition of the NHEJ factor DNA-PK, under conditions of MMS-induced PARP-1 hyperactivation, enhanced necrotic cell death. These data suggest that PARP-1 hyperactivation is a protective mechanism triggering the classical-NHEJ DNA repair pathway when the primary alkylated base damage repair pathway is compromised.

  13. Hyperactivation of PARP triggers nonhomologous end-joining in repair-deficient mouse fibroblasts.

    Directory of Open Access Journals (Sweden)

    Natalie R Gassman

    Full Text Available Regulation of poly(ADP-ribose (PAR synthesis and turnover is critical to determining cell fate after genotoxic stress. Hyperactivation of PAR synthesis by poly(ADP-ribose polymerase-1 (PARP-1 occurs when cells deficient in DNA repair are exposed to genotoxic agents; however, the function of this hyperactivation has not been adequately explained. Here, we examine PAR synthesis in mouse fibroblasts deficient in the base excision repair enzyme DNA polymerase β (pol β. The extent and duration of PARP-1 activation was measured after exposure to either the DNA alkylating agent, methyl methanesulfonate (MMS, or to low energy laser-induced DNA damage. There was strong DNA damage-induced hyperactivation of PARP-1 in pol β nullcells, but not in wild-type cells. In the case of MMS treatment, PAR synthesis did not lead to cell death in the pol β null cells, but instead resulted in increased PARylation of the nonhomologous end-joining (NHEJ protein Ku70 and increased association of Ku70 with PARP-1. Inhibition of the NHEJ factor DNA-PK, under conditions of MMS-induced PARP-1 hyperactivation, enhanced necrotic cell death. These data suggest that PARP-1 hyperactivation is a protective mechanism triggering the classical-NHEJ DNA repair pathway when the primary alkylated base damage repair pathway is compromised.

  14. Sister chromatid gene conversion is a prominent double-strand break repair pathway in mammalian cells

    OpenAIRE

    Johnson, Roger D.; Jasin, Maria

    2000-01-01

    In mammalian cells, repair of DNA double-strand breaks (DSBs) occurs by both homologous and non-homologous mechanisms. By definition, homologous recombination requires a template with sufficient sequence identity to the damaged molecule in order to direct repair. We now show that the sister chromatid acts as a repair template in a substantial proportion of DSB repair events. The outcome of sister chromatid repair is primarily gene conversion unassociated with reciprocal exchange. This contras...

  15. Burst strength of laparoscopic and open hernia repair.

    Science.gov (United States)

    Brockman, J B; Patterson, N W; Richardson, W S

    2004-03-01

    There are few reports of overall strength of laparoscopic and open incisional hernia repair. After anesthesia, a 2-inch circular defect was made in the abdominal wall of 28 female swine. Gore-Tex DualMesh Biomaterial (W. L. Gore & Associates, Flagstaff, AZ) was used for all repairs. Sixteen animals underwent open repair and 12 underwent laparoscopic repair. Burst strength was detected within 2 weeks and at 6 weeks by euthanizing the animals and insufflating the abdominal cavity with water while measuring the intraabdominal pressure until it could no longer be pressurized. Three events occurred after insufflation: rupture around patch (R), dissection from insufflation or pressure monitoring sites (D), or rectal prolapse (P). Failure after open early repair occurred at 289 (range 219-388) mmHg with 7-R, 1-P and late 289 (196-343) mmHg with 1-R, 6-P. Failure after laparoscopic early repair occurred at 259 (191-388) mmHg with 4-R, 1-P, 1-D and late 291 (140-330) mmHg with 2-R, 1-P, 3-D. Late groups were less likely to rupture. Both hernia repairs are durable at early and late periods. Tissue ingrowth adds to repair strength. We could not show that one repair was stronger than the other. Nonetheless, laparoscopic repair tended to degrade by dissection, which was our highest pressure event.

  16. Digestive Enzyme Replacement Therapy: Pancreatic Enzymes and Lactase.

    Science.gov (United States)

    Felicilda-Reynaldo, Rhea Faye D; Kenneally, Maria

    2016-01-01

    Maldigestion occurs when digestive enzymes are lacking to help break complex food components into absorbable nutrients within the gastrointestinal tract. Education is needed to help patients manage the intricacies of digestive enzyme replacement therapies and ensure their effectiveness in reducing symptoms of maldigestion.

  17. Repair welding process of friction stir welding groove defect

    Institute of Scientific and Technical Information of China (English)

    LIU Hui-jie; ZHANG Hui-jie

    2009-01-01

    The groove defect formed in the friction stir welding dramatically deteriorates weld appearances and mechanical properties of the joints owing to its larger size and penetration. Therefore, the friction stir repair welding was utilized to remove such a groove defect, and the focus was placed on the mechanical properties and microstructural characteristics of the repair joints so as to obtain an optimum repair welding process. The experimental results indicate that the groove defect can be removed by friction stir repair welding, and the offset repair welding process is superior to the symmetrical repair welding process. In the symmetrical repair welding process, a large number of fine cavity defects and an obvious aggregation of hard-brittle phase Al2Cu occur, accordingly the mechanical properties of the repair joint are weakened, and the fracture feature of repair joint is partially brittle and partially plastic. A good-quality repair joint can be obtained by the offset repair welding process, and the repair joint is fractured near the interface between the weld nugget zone and thermal-mechanically affected zone.

  18. Percutaneous mitral valve repair.

    Science.gov (United States)

    Gillinov, A Marc; Liddicoat, John R

    2006-01-01

    Surgical mitral valve repair is the procedure of choice to treat mitral regurgitation of all etiologies. Whereas annuloplasty is the cornerstone of mitral valve repair, a variety of other surgical techniques are utilized to correct dysfunction of the leaflets and subvalvular apparatus; in most cases, surgical repair entails application of multiple repair techniques in each patient. Preclinical studies and early human experience have demonstrated that some of these surgical repair techniques can be performed using percutaneous approaches. Specifically, there has been great progress in the development of novel technology to facilitate percutaneous annuloplasty and percutaneous edge-to-edge repair. The objectives of this report were to (1) discuss the surgical foundations for these percutaneous approaches; (2) review device design and experimental and clinical results of percutaneous valve repair; and (3) address future directions, including the key challenges of patient selection and clinical trial design.

  19. Myasis occuring in a neonate

    Science.gov (United States)

    Obasa, Temitope O.; Sowunmi, Funmilola Olusola

    2012-01-01

    Myasis is the infestation of skin by larvae or maggots of a variety of flies. It is a condition that occurs more commonly in adults who are living and/or have visited tropical countries. It rarely occurs in neonates, and even when seen, only few larvae are extracted. This case report describes myasis occurring in an 11-day-old female who had 47 larvae in her skin. PMID:23355934

  20. Myasis occuring in a neonate

    Directory of Open Access Journals (Sweden)

    Temitope O. Obasa

    2012-12-01

    Full Text Available Myasis is the infestation of skin by larvae or maggots of a variety of flies. It is a condition that occurs more commonly in adults who are living and/or have visited tropical countries. It rarely occurs in neonates, and even when seen, only few larvae are extracted. This case report describes myasis occurring in an 11-day-old female who had 47 larvae in her skin.

  1. Enhanced DNA repair of cyclobutane pyrimidine dimers changes the biological response to UV-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yarosh, Daniel B

    2002-11-30

    The goal of DNA repair enzyme therapy is the same as that for gene therapy: to rescue a defective proteome/genome by introducing a substitute protein/DNA. The danger of inadequate DNA repair is highlighted in the genetic disease xeroderma pigmentosum. These patients are hypersensitive to sunlight and develop multiple cutaneous neoplasms very early in life. The bacterial DNA repair enzyme T4 endonuclease V was shown over 25 years ago to be capable of reversing the defective repair in xeroderma pigmentosum cells. This enzyme, packaged in an engineered delivery vehicle, has been shown to traverse the stratum corneum, reach the nuclei of living cells of the skin, and enhance the repair of UV-induced cyclobutane pyrimidine dimers (CPD). In such a system, changes in DNA repair, mutagenesis, and cell signaling can be studied without manipulation of the genome.

  2. Studying repair of a single protein-bound nick in vivo using the Flp-nick system

    DEFF Research Database (Denmark)

    2012-01-01

    damage mimics a stabilized topoisomerase I-DNA cleavage complex. DNA topoisomerases are ubiquitous enzymes that relieve topological stress in the DNA arising during DNA replication or transcription. During this process, they make transient enzyme-DNA cleavage complexes, which normally are reversed...... by a rapid ligation step. However, aberrant long-lived enzyme-DNA complexes may occur frequently due to either endogenous or exogenous damage, and the cellular repair machinery therefore needs to be able to eliminate this type of damage. This chapter describes how to establish the Flp-nick system in S....... cerevisiae, how to detect FlpH305L at the FRT site using a modified chromatin immunoprecipitation assay where formaldehyde fixation is omitted, and how to monitor nicking at the FRT site by alkaline denaturing gel analysis...

  3. Dental materials for cleft palate repair.

    Science.gov (United States)

    Sharif, Faiza; Ur Rehman, Ihtesham; Muhammad, Nawshad; MacNeil, Sheila

    2016-04-01

    Numerous bone and soft tissue grafting techniques are followed to repair cleft of lip and palate (CLP) defects. In addition to the gold standard surgical interventions involving the use of autogenous grafts, various allogenic and xenogenic graft materials are available for bone regeneration. In an attempt to discover minimally invasive and cost effective treatments for cleft repair, an exceptional growth in synthetic biomedical graft materials have occurred. This study gives an overview of the use of dental materials to repair cleft of lip and palate (CLP). The eligibility criteria for this review were case studies, clinical trials and retrospective studies on the use of various types of dental materials in surgical repair of cleft palate defects. Any data available on the surgical interventions to repair alveolar or palatal cleft, with natural or synthetic graft materials was included in this review. Those datasets with long term clinical follow-up results were referred to as particularly relevant. The results provide encouraging evidence in favor of dental and other related biomedical materials to fill the gaps in clefts of lip and palate. The review presents the various bones and soft tissue replacement strategies currently used, tested or explored for the repair of cleft defects. There was little available data on the use of synthetic materials in cleft repair which was a limitation of this study. In conclusion although clinical trials on the use of synthetic materials are currently underway the uses of autologous implants are the preferred treatment methods to date.

  4. Predictors of hepatitis B cure using gene therapy to deliver DNA cleavage enzymes: a mathematical modeling approach.

    Directory of Open Access Journals (Sweden)

    Joshua T Schiffer

    Full Text Available Most chronic viral infections are managed with small molecule therapies that inhibit replication but are not curative because non-replicating viral forms can persist despite decades of suppressive treatment. There are therefore numerous strategies in development to eradicate all non-replicating viruses from the body. We are currently engineering DNA cleavage enzymes that specifically target hepatitis B virus covalently closed circular DNA (HBV cccDNA, the episomal form of the virus that persists despite potent antiviral therapies. DNA cleavage enzymes, including homing endonucleases or meganucleases, zinc-finger nucleases (ZFNs, TAL effector nucleases (TALENs, and CRISPR-associated system 9 (Cas9 proteins, can disrupt specific regions of viral DNA. Because DNA repair is error prone, the virus can be neutralized after repeated cleavage events when a target sequence becomes mutated. DNA cleavage enzymes will be delivered as genes within viral vectors that enter hepatocytes. Here we develop mathematical models that describe the delivery and intracellular activity of DNA cleavage enzymes. Model simulations predict that high vector to target cell ratio, limited removal of delivery vectors by humoral immunity, and avid binding between enzyme and its DNA target will promote the highest level of cccDNA disruption. Development of de novo resistance to cleavage enzymes may occur if DNA cleavage and error prone repair does not render the viral episome replication incompetent: our model predicts that concurrent delivery of multiple enzymes which target different vital cccDNA regions, or sequential delivery of different enzymes, are both potentially useful strategies for avoiding multi-enzyme resistance. The underlying dynamics of cccDNA persistence are unlikely to impact the probability of cure provided that antiviral therapy is given concurrently during eradication trials. We conclude by describing experiments that can be used to validate the model, which

  5. Repair of dense connective tissues via biomaterial-mediated matrix reprogramming of the wound interface.

    Science.gov (United States)

    Qu, Feini; Pintauro, Michael P; Haughan, Joanne E; Henning, Elizabeth A; Esterhai, John L; Schaer, Thomas P; Mauck, Robert L; Fisher, Matthew B

    2015-01-01

    Repair of dense connective tissues in adults is limited by their intrinsic hypocellularity and is exacerbated by a dense extracellular matrix (ECM) that impedes cellular migration to and local proliferation at the wound site. Conversely, healing in fetal tissues occurs due in part to an environment conducive to cell mobility and division. Here, we investigated whether the application of a degradative enzyme, collagenase, could reprogram the adult wound margin to a more fetal-like state, and thus abrogate the biophysical impediments that hinder migration and proliferation. We tested this concept using the knee meniscus, a commonly injured structure for which few regenerative approaches exist. To focus delivery and degradation to the wound interface, we developed a system in which collagenase was stored inside poly(ethylene oxide) (PEO) electrospun nanofibers and released upon hydration. Through a series of in vitro and in vivo studies, our findings show that partial digestion of the wound interface improves repair by creating a more compliant and porous microenvironment that expedites cell migration to and/or proliferation at the wound margin. This innovative approach of targeted manipulation of the wound interface, focused on removing the naturally occurring barriers to adult tissue repair, may find widespread application in the treatment of injuries to a variety of dense connective tissues.

  6. Epigenetic reduction of DNA repair in progression togastrointestinal cancer

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Deficiencies in DNA repair due to inherited germ-linemutations in DNA repair genes cause increased risk ofgastrointestinal (GI) cancer. In sporadic GI cancers,mutations in DNA repair genes are relatively rare.However, epigenetic alterations that reduce expressionof DNA repair genes are frequent in sporadic GI cancers.These epigenetic reductions are also found in fielddefects that give rise to cancers. Reduced DNA repairlikely allows excessive DNA damages to accumulatein somatic cells. Then either inaccurate translesionsynthesis past the un-repaired DNA damages or errorproneDNA repair can cause mutations. ErroneousDNA repair can also cause epigenetic alterations (i.e. ,epimutations, transmitted through multiple replicationcycles). Some of these mutations and epimutations maycause progression to cancer. Thus, deficient or absentDNA repair is likely an important underlying cause ofcancer. Whole genome sequencing of GI cancers showthat between thousands to hundreds of thousands ofmutations occur in these cancers. Epimutations thatreduce DNA repair gene expression and occur early inprogression to GI cancers are a likely source of this highgenomic instability. Cancer cells deficient in DNA repairare more vulnerable than normal cells to inactivation byDNA damaging agents. Thus, some of the most clinicallyeffective chemotherapeutic agents in cancer treatmentare DNA damaging agents, and their effectivenessoften depends on deficient DNA repair in cancer cells.Recently, at least 18 DNA repair proteins, each activein one of six DNA repair pathways, were found to besubject to epigenetic reduction of expression in GIcancers. Different DNA repair pathways repair differenttypes of DNA damage. Evaluation of which DNA repairpathway(s) are deficient in particular types of GI cancerand/or particular patients may prove useful in guidingchoice of therapeutic agents in cancer therapy.

  7. Computational enzyme design: transitioning from catalytic proteins to enzymes.

    Science.gov (United States)

    Mak, Wai Shun; Siegel, Justin B

    2014-08-01

    The widespread interest in enzymes stem from their ability to catalyze chemical reactions under mild and ecologically friendly conditions with unparalleled catalytic proficiencies. While thousands of naturally occurring enzymes have been identified and characterized, there are still numerous important applications for which there are no biological catalysts capable of performing the desired chemical transformation. In order to engineer enzymes for which there is no natural starting point, efforts using a combination of quantum chemistry and force-field based protein molecular modeling have led to the design of novel proteins capable of catalyzing chemical reactions not catalyzed by naturally occurring enzymes. Here we discuss the current status and potential avenues to pursue as the field of computational enzyme design moves forward.

  8. Food Enzymes

    Science.gov (United States)

    McBroom, Rachel; Oliver-Hoyo, Maria T.

    2007-01-01

    Many students view biology and chemistry as two unrelated, separate sciences; how these courses are generally taught in high schools may do little to change that impression. The study of enzymes provide a great opportunity for both biology and chemistry teachers to share with students the interdisciplinary nature of science. This article describes…

  9. Food Enzymes

    Science.gov (United States)

    McBroom, Rachel; Oliver-Hoyo, Maria T.

    2007-01-01

    Many students view biology and chemistry as two unrelated, separate sciences; how these courses are generally taught in high schools may do little to change that impression. The study of enzymes provide a great opportunity for both biology and chemistry teachers to share with students the interdisciplinary nature of science. This article describes…

  10. Enzyme immunoassay

    DEFF Research Database (Denmark)

    Feldt-Rasmussen, B; Dinesen, B; Deckert, M

    1985-01-01

    An enzyme linked immunoadsorbent assay for urinary albumin using commercially available reagents is described. The assay range is 2.5-120 micrograms/l. When samples are analysed in two standard dilutions, the assayable albumin concentration range is 2.5-240 mg/l, covering the clinical range from...

  11. DNA repair and radiation sensitivity in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.J.C.; Stackhouse, M. [Los Alamos National Lab., NM (United States); Chen, D.S. [Rochester Univ., NY (United States). Dept. of Radiation Oncology

    1993-02-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  12. DNA repair and radiation sensitivity in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.J.C.; Stackhouse, M. (Los Alamos National Lab., NM (United States)); Chen, D.S. (Rochester Univ., NY (United States). Dept. of Radiation Oncology)

    1993-01-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  13. Repairs of composite structures

    Science.gov (United States)

    Roh, Hee Seok

    Repair on damaged composite panels was conducted. To better understand adhesively bonded repair, the study investigates the effect of design parameters on the joint strength. The design parameters include bondline length, thickness of adherend and type of adhesive. Adhesives considered in this study were tested to measure their tensile material properties. Three types of adhesively bonded joints, single strap, double strap, and single lap joint were considered under changing bondline lengths, thickness of adherend and type of adhesive. Based on lessons learned from bonded joints, a one-sided patch repair method for composite structures was conducted. The composite patch was bonded to the damaged panel by either film adhesive FM-73M or paste adhesive EA-9394 and the residual strengths of the repaired specimens were compared under varying patch sizes. A new repair method using attachments has been suggested to enhance the residual strength. Results obtained through experiments were analyzed using finite element analysis to provide a better repair design and explain the experimental results. It was observed that the residual strength of the repaired specimen was affected by patch length. Method for rapid repairs of damaged composite structures was investigated. The damage was represented by a circular hole in a composite laminated plate. Pre-cured composite patches were bonded with a quick-curing commercial adhesive near (rather than over) the hole. Tensile tests were conducted on specimens repaired with various patch geometries. The test results showed that, among the methods investigated, the best repair method restored over 90% of the original strength of an undamaged panel. The interfacial stresses in the adhesive zone for different patches were calculated in order to understand the efficiencies of the designs of these patch repairs. It was found that the composite patch that yielded the best strength had the lowest interfacial peel stress between the patch and

  14. Destabilizing DNA during Rejoining Enhances Fidelity of Repair.

    Directory of Open Access Journals (Sweden)

    Richard Robinson

    2015-08-01

    Full Text Available A new study shows that during repair of DNA, the effect of a single-strand annealing protein is to destabilize DNA duplex formation so that annealing only occurs between perfectly matched strands; the protein then clamps the strands together for repair. Read the Research Article.

  15. Workshop on DNA repair.

    NARCIS (Netherlands)

    A.R. Lehmann (Alan); J.H.J. Hoeijmakers (Jan); A.A. van Zeeland (Albert); C.M.P. Backendorf (Claude); B.A. Bridges; A. Collins; R.P.D. Fuchs; G.P. Margison; R. Montesano; E. Moustacchi; A.T. Natarajan; M. Radman; A. Sarasin; E. Seeberg; C.A. Smith; M. Stefanini (Miria); L.H. Thompson; G.P. van der Schans; C.A. Weber (Christine); M.Z. Zdzienika

    1992-01-01

    textabstractA workshop on DNA repair with emphasis on eukaryotic systems was held, under the auspices of the EC Concerted Action on DNA Repair and Cancer, at Noordwijkerhout (The Netherlands) 14-19 April 1991. The local organization of the meeting was done under the auspices of the Medical Genetic C

  16. Laparoscopic lumbar hernia repair.

    Science.gov (United States)

    Madan, Atul K; Ternovits, Craig A; Speck, Karen E; Pritchard, F Elizabeth; Tichansky, David S

    2006-04-01

    Lumbar hernias are rare clinical entities that often pose a challenge for repair. Because of the surrounding anatomy, adequate surgical herniorraphy is often difficult. Minimally invasive surgery has become an option for these hernias. Herein, we describe two patients with lumbar hernias (one with a recurrent traumatic hernia and one with an incisional hernia). Both of these hernias were successfully repaired laparoscopically.

  17. Augmented Reality Repair Guidance System

    Directory of Open Access Journals (Sweden)

    Sidharth Bhatia

    2012-07-01

    Full Text Available The daily life of a common man revolves around various forms of appliances/gadgets he uses throughout the day such as a mobile phone, laptop, printer, microwave oven, washing machine, etc. Although these appliances/gadgets are taken by most of the people for granted, the problem occurs when any of these things do not work as they are expected to. Getting them to the repair shops for every small glitch is expensive as well as time consuming. Although most of the companies which produce these appliances/gadgets do supply them with basic manuals, which deal with how to solve these minor issues, but reading them and at the same time repairing the corresponding appliance/gadget can be a frustrating task at times. These problems can be reduced to a large extent if some kind of live guidance is available. In this paper we propose a method to do so with the help of an augmented reality based system that will guide the user to carry out small scale repair jobs on these gadgets. All that is required is a decent webcam and a computing device, with a processor of 1 GHz or more and a display screen.

  18. Dynamic regulation of cerebral DNA repair genes by psychological stress

    DEFF Research Database (Denmark)

    Forsberg, Kristin; Aalling, Nadia; Wörtwein, Gitta

    2015-01-01

    for maintaining genomic integrity. The aim of the present study was to characterize the pattern of cerebral DNA repair enzyme regulation after stress through the quantification of a targeted range of gene products involved in different types of DNA repair. 72 male Sprague-Dawley rats were subjected to either...... was seen in HC, but with overall smaller effects and without the induction after acute stress. Nuclear DNA damage from oxidation as measured by the comet assay was unaffected by stress in both regions. We conclude that psychological stress have a dynamic influence on brain DNA repair gene expression...

  19. A Review of Recent Experiments on Step-to-Step “Hand-off” of the DNA Intermediates in Mammalian Base Excision Repair Pathways1

    OpenAIRE

    Prasad, R.; Beard, W A; Batra, V. K.; Liu, Y.; Shock, D. D.; Wilson, S H

    2011-01-01

    The current “working model” for mammalian base excision repair involves two sub-pathways termed single-nucleotide base excision repair and long patch base excision repair that are distinguished by their repair patch sizes and the enzymes/co-factors involved. These base excision repair sub-pathways are designed to sequester the various DNA intermediates, passing them along from one step to the next without allowing these toxic molecules to trigger cell cycle arrest, necrotic cell death, or apo...

  20. DNA repair protocols

    DEFF Research Database (Denmark)

    Bjergbæk, Lotte

    In its 3rd edition, this Methods in Molecular Biology(TM) book covers the eukaryotic response to genomic insult including advanced protocols and standard techniques in the field of DNA repair. Offers expert guidance for DNA repair, recombination, and replication. Current knowledge of the mechanisms...... that regulate DNA repair has grown significantly over the past years with technology advances such as RNA interference, advanced proteomics and microscopy as well as high throughput screens. The third edition of DNA Repair Protocols covers various aspects of the eukaryotic response to genomic insult including...... recent advanced protocols as well as standard techniques used in the field of DNA repair. Both mammalian and non-mammalian model organisms are covered in the book, and many of the techniques can be applied with only minor modifications to other systems than the one described. Written in the highly...

  1. INTERNAL REPAIR OF PIPELINES

    Energy Technology Data Exchange (ETDEWEB)

    Bill Bruce; Nancy Porter; George Ritter; Matt Boring; Mark Lozev; Ian Harris; Bill Mohr; Dennis Harwig; Robin Gordon; Chris Neary; Mike Sullivan

    2005-07-20

    The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: (1) Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, under congested intersections, and under railway crossings. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. (3) Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. (4) The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiber-reinforced composite liner were only marginally greater than that of pipe sections without

  2. A matter of life or death: modeling DNA damage and repair in bacteria.

    Science.gov (United States)

    Karschau, Jens; de Almeida, Camila; Richard, Morgiane C; Miller, Samantha; Booth, Ian R; Grebogi, Celso; de Moura, Alessandro P S

    2011-02-16

    DNA damage is a hazard all cells must face, and evolution has created a number of mechanisms to repair damaged bases in the chromosome. Paradoxically, many of these repair mechanisms can create double-strand breaks in the DNA molecule which are fatal to the cell. This indicates that the connection between DNA repair and death is far from straightforward, and suggests that the repair mechanisms can be a double-edged sword. In this report, we formulate a mathematical model of the dynamics of DNA damage and repair, and we obtain analytical expressions for the death rate. We predict a counterintuitive relationship between survival and repair. We can discriminate between two phases: below a critical threshold in the number of repair enzymes, the half-life decreases with the number of repair enzymes, but becomes independent of the number of repair enzymes above the threshold. We are able to predict quantitatively the dependence of the death rate on the damage rate and other relevant parameters. We verify our analytical results by simulating the stochastic dynamics of DNA damage and repair. Finally, we also perform an experiment with Escherichia coli cells to test one of the predictions of our model.

  3. DNA damage by reactive species: Mechanisms, mutation and repair.

    Science.gov (United States)

    Jena, N R

    2012-07-01

    DNA is continuously attacked by reactive species that can affect its structure and function severely. Structural modifications to DNA mainly arise from modifications in its bases that primarily occur due to their exposure to different reactive species. Apart from this, DNA strand break, inter- and intra-strand crosslinks and DNA-protein crosslinks can also affect the structure of DNA significantly. These structural modifications are involved in mutation, cancer and many other diseases. As it has the least oxidation potential among all the DNA bases, guanine is frequently attacked by reactive species, producing a plethora of lethal lesions. Fortunately, living cells are evolved with intelligent enzymes that continuously protect DNA from such damages. This review provides an overview of different guanine lesions formed due to reactions of guanine with different reactive species. Involvement of these lesions in inter- and intra-strand crosslinks, DNA-protein crosslinks and mutagenesis are discussed. How certain enzymes recognize and repair different guanine lesions in DNA are also presented.

  4. DNA damage by reactive species: Mechanisms, mutation and repair

    Indian Academy of Sciences (India)

    N R Jena

    2012-07-01

    DNA is continuously attacked by reactive species that can affect its structure and function severely. Structural modifications to DNA mainly arise from modifications in its bases that primarily occur due to their exposure to different reactive species. Apart from this, DNA strand break, inter- and intra-strand crosslinks and DNA–protein crosslinks can also affect the structure of DNA significantly. These structural modifications are involved in mutation, cancer and many other diseases. As it has the least oxidation potential among all the DNA bases, guanine is frequently attacked by reactive species, producing a plethora of lethal lesions. Fortunately, living cells are evolved with intelligent enzymes that continuously protect DNA from such damages. This review provides an overview of different guanine lesions formed due to reactions of guanine with different reactive species. Involvement of these lesions in inter- and intra-strand crosslinks, DNA–protein crosslinks and mutagenesis are discussed. How certain enzymes recognize and repair different guanine lesions in DNA are also presented.

  5. Repair and regeneration in endodontics.

    Science.gov (United States)

    Lin, L M; Rosenberg, P A

    2011-10-01

    The ideal objective of treatment of established diseases, including irreversible pulpitis and apical periodontitis, is to achieve wound healing. Wound healing can result in repair or regeneration. The ultimate goal of wound healing is to restore the original architecture and biological function of the injured tissue or organ. Although humans are equipped with powerful innate and adaptive immune defence mechanisms, many intrinsic and extrinsic factors can affect wound healing. Complete regeneration following injury in humans can occur only in the pre-natal foetus within 24 weeks of gestation. Post-natal wounds including irreversible pulpitis or apical periodontitis always heal by repair or by a combination of repair and regeneration. Somatic cells, such as fibroblasts, macrophages, cementoblasts and osteoblasts, in the pulp and periapical tissues have limited potential for regeneration following injury and lack of telomerase. Wound healing of irreversible pulpitis and apical periodontitis requires recruitment and differentiation of progenitor/stem cells into tissue-committed somatic cells. Stem cell differentiation is regulated by intrinsic factors and extrinsic micro-environmental cues. Functionality of stem cells appears to show an age-related decline because of the change in intrinsic properties and diminished signals within the extrinsic local and systemic environment that modulate the function of stem cells or their progeny. Infection induces an immuno-inflammatory response and tissue destruction, which hinders the potential of tissue regeneration. Therefore, prevention, early detection and treatment of inflammation/infection of pulpal and periapical disease can enhance regeneration and minimize the repair of pulpal and periapical tissues after endodontic therapy. © 2011 International Endodontic Journal.

  6. Angiodysplasia Occurring in Jejunal Diverticulosis

    OpenAIRE

    Edward A Jones; Hugh Chaun; Phillip Switzer; David J Clow; Ronald J Hancock

    1990-01-01

    The first case of angiodysplasia occurring in acquired jejunal diverticulosis is reported. The patient presented with occult gastrointestinal bleeding and chronic anemia, and was created successfully by resection of a 25 cm long segment of jejunum. Possible pathogenetic mechanisms for both angiodysplasia and jejunal diverticulosis are discussed.

  7. Protein damage and repair controlling seed vigor and longevity.

    Science.gov (United States)

    Ogé, Laurent; Broyart, Caroline; Collet, Boris; Godin, Béatrice; Jallet, Denis; Bourdais, Gildas; Job, Dominique; Grappin, Philippe

    2011-01-01

    The formation of abnormal isoaspartyl residues derived from aspartyl or asparaginyl residues is a major source of spontaneous protein misfolding in cells. The repair enzyme protein L: -isoaspartyl methyltransferase (PIMT) counteracts such damage by catalyzing the conversion of abnormal isoaspartyl residues to their normal aspartyl forms. Thus, this enzyme contributes to the survival of many organisms, including plants. Analysis of the accumulation of isoaspartyl-containing proteins and its modulation by the PIMT repair pathway, using germination tests, immunodetection, enzymatic assays, and HPLC analysis, gives new insights in understanding controlling mechanisms of seed longevity and vigor.

  8. INTERNAL REPAIR OF PIPELINES

    Energy Technology Data Exchange (ETDEWEB)

    Robin Gordon; Bill Bruce; Ian Harris; Dennis Harwig; George Ritter; Bill Mohr; Matt Boring; Nancy Porter; Mike Sullivan; Chris Neary

    2004-12-31

    The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: (1) Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, under congested intersections, and under railway crossings. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. (3) Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. (4) The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiber-reinforced composite liner were only marginally greater than that of pipe sections without

  9. Repairing Multiple Failures with Coordinated and Adaptive Regenerating Codes

    CERN Document Server

    Kermarrec, Anne-Marie; Scouarnec, Nicolas Le

    2011-01-01

    Erasure correcting codes are widely used to ensure data persistence in distributed storage systems. This paper addresses the repair of such codes in the presence of simultaneous failures. It is crucial to maintain the required redundancy over time to prevent permanent data losses. We go beyond existing work (i.e., regenerating codes by Dimakis et al.) and propose coordinated regenerating codes allowing devices to coordinate during simultaneous repairs thus reducing the costs further. We provide closed form expressions of the communication costs of our new codes depending on the number of live devices and the number of devices being repaired. We prove that deliberately delaying repairs does not bring additional gains in itself. This means that regenerating codes are optimal as long as each failure can be repaired before a second one occurs. Yet, when multiple failures are detected simultaneously, we prove that our coordinated regenerating codes are optimal and outperform uncoordinated repairs (with respect to ...

  10. INTERNAL REPAIR OF PIPELINES

    Energy Technology Data Exchange (ETDEWEB)

    Robin Gordon; Bill Bruce; Ian Harris; Dennis Harwig; George Ritter; Bill Mohr; Matt Boring; Nancy Porter; Mike Sullivan; Chris Neary

    2004-08-17

    The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: (1) Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, under congested intersections, and under railway. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. (3) Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. (4) The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiber-reinforced composite liner were only marginally greater than that of pipe sections without liners

  11. Naturally Occurring Radioactive Materials (NORM)

    Energy Technology Data Exchange (ETDEWEB)

    Gray, P. [ed.

    1997-02-01

    This paper discusses the broad problems presented by Naturally Occuring Radioactive Materials (NORM). Technologically Enhanced naturally occuring radioactive material includes any radionuclides whose physical, chemical, radiological properties or radionuclide concentration have been altered from their natural state. With regard to NORM in particular, radioactive contamination is radioactive material in an undesired location. This is a concern in a range of industries: petroleum; uranium mining; phosphorus and phosphates; fertilizers; fossil fuels; forestry products; water treatment; metal mining and processing; geothermal energy. The author discusses in more detail the problem in the petroleum industry, including the isotopes of concern, the hazards they present, the contamination which they cause, ways to dispose of contaminated materials, and regulatory issues. He points out there are three key programs to reduce legal exposure and problems due to these contaminants: waste minimization; NORM assesment (surveys); NORM compliance (training).

  12. Chronic Pain after Inguinal Hernia Repair

    OpenAIRE

    2014-01-01

    Background. Chronic postherniorrhaphy groin pain is defined as pain lasting >6 months after surgery, which is one of the most important complications occurring after inguinal hernia repair, which occurs with greater frequency than previously thought. Material and Methods. Patients undergoing elective inguinal hernioplasty in Victoria Hospital from November 2011 to May 2013 were included in the study. A total of 227 patients met the inclusion criteria and were available for followup at end of ...

  13. Salvage hypospadias repairs

    Directory of Open Access Journals (Sweden)

    Sripathi V

    2008-01-01

    Full Text Available Aim: Review of our experience and to develop an algorithm for salvage procedures in the management of hypospadias cripples and treatment of urethral strictures following hypospadias repair. Methods: This is a retrospective review of hypospadias surgeries over a 41-month period. Out of a total 168 surgeries, 20 were salvage/re-operative repairs. In three children a Duplay repair was feasible, while in four others a variety of single-stage repairs could be done. The repair was staged in seven children - buccal mucosal grafts (BMGs in five, buccal mucosal tube in one, and skin graft in one. Five children with dense strictures were managed by dorsal BMG inlay grafting in one, vascularized tunical onlay grafting on the ventrum in one, and a free tunical patch in one. Three children were treated by internal urethrotomy and stenting for four weeks with a poor outcome. Results: The age of children ranged from 1.5-15 years (mean 4.5. Follow-up ranged from 3 months to 3.5 years. Excellent results were obtained in 10 children (50% with a well-surfaced erect penis and a slit-like meatus. Glans closure could not be achieved and meatus was coronal in three. Two children developed fistulae following a Duplay repair and following a staged BMG. Three repairs failed completely - a composite repair broke down, a BMG tube stenosed with a proximal leak, and a stricture recurred with loss of a ventral free tunical graft. Conclusions: In salvage procedures performed on hypospadias cripples, a staged repair with buccal mucosa as an inlay in the first stage followed by tubularization 4-6 months later provides good results. A simple algorithm to plan corrective surgery in failed hypospadias cases and obtain satisfactory results is devised.

  14. Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells

    Science.gov (United States)

    Suzuki, Tetsuya; Yasui, Manabu

    2016-01-01

    Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Cells with a loss of heterozygosity (LOH) due to homologous recombination (HR) or nonhomologous end joining (NHEJ) can be restored with or without site-directed DSB induction. BLM cells exhibited a high frequency of spontaneous interallelic HR with crossover, but noncrossover events with long-tract gene conversions also occurred. Despite the highly interallelic HR events, BLM cells predominantly produced hemizygous LOH by spontaneous deletion. These phenotypes manifested during repair of DSBs. Both NHEJ and HR appropriately repaired DSBs in BLM cells, resulting in hemizygous and homozygous LOHs, respectively. However, the magnitude of the LOH was exacerbated in BLM cells, as evidenced by large deletions and long-tract gene conversions with crossover. BLM helicase suppresses the elongation of branch migration and crossover of double Holliday junctions (HJs) during HR repair, and a deficiency in this enzyme causes collapse, abnormal elongation, and/or preferable resolution to crossover of double HJs, resulting in a large-scale LOH. This mechanism underlies the predisposition for cancer in BS. PMID:27601585

  15. Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells.

    Science.gov (United States)

    Suzuki, Tetsuya; Yasui, Manabu; Honma, Masamitsu

    2016-12-01

    Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Cells with a loss of heterozygosity (LOH) due to homologous recombination (HR) or nonhomologous end joining (NHEJ) can be restored with or without site-directed DSB induction. BLM cells exhibited a high frequency of spontaneous interallelic HR with crossover, but noncrossover events with long-tract gene conversions also occurred. Despite the highly interallelic HR events, BLM cells predominantly produced hemizygous LOH by spontaneous deletion. These phenotypes manifested during repair of DSBs. Both NHEJ and HR appropriately repaired DSBs in BLM cells, resulting in hemizygous and homozygous LOHs, respectively. However, the magnitude of the LOH was exacerbated in BLM cells, as evidenced by large deletions and long-tract gene conversions with crossover. BLM helicase suppresses the elongation of branch migration and crossover of double Holliday junctions (HJs) during HR repair, and a deficiency in this enzyme causes collapse, abnormal elongation, and/or preferable resolution to crossover of double HJs, resulting in a large-scale LOH. This mechanism underlies the predisposition for cancer in BS. Copyright © 2016 Suzuki et al.

  16. Lymphangiogenesis Occurring in Transplanted Corneas

    Institute of Scientific and Technical Information of China (English)

    LING Shiqi; XIAO Qing; HU Yanhua

    2006-01-01

    To study corneal lymphangiogenesis after corneal transplantation, corneal allogenic transplantation models were established in rats. 8 female Wister rats were used as donors, and 16 Sprague Dawley (SD) rats were used as recipients and 2 SD served as controls. Corneal lymphangiogenesis and hemangiogenesis was examined by electron microscopy 1 and 2 weeks after corneal penetrating transplantation, and the expression of lymphatic vessel endothelial receptor (LYVE-1) was examined 1, 3, 7, 14 days after the transplantation respectively. In addition, 19 allograft failed human corneas were examined by 5'-nase-alkaline phosphatase (5'-NA-ALP) doubleenzyme-histochemistry staining to detect corneal lymphangiogenesis and hemangiogenesis. By immunohistochemistry for LYVE-1, it was found that blown lymphatics were localized in the stroma 3days after the corneal transplantation. With electron microscopy, new lymphatic vessels and blood vessels were found 1 and 2 weeks after the corneal transplantation. By 5'-NA-ALP enzyme-histochemistry, corneal hemangiogenesis was found in all allograft failed huma n corneas and 5 of 19(26.3%) cases had developed corneal lymphangiogenesis. It is concluded that corneal lymphangiogenesis is present after corneal transplantation, which may play an important role in allograft rejection.

  17. Princess takamatsu symposium on DNA repair and human cancers.

    Science.gov (United States)

    Loeb, Lawrence A; Nishimura, Susumu

    2010-06-01

    The 40th International Symposium of the Princess Takamatsu Cancer Research Fund, entitled "DNA Repair and Human Cancers," was held on November 10-12, 2009 at Hotel Grand Palace, Tokyo, Japan. The meeting focused on the role of DNA repair in preventing mutations by endogenous and exogenous DNA damage and increasing the efficacy of chemotherapeutic agents by interfering with DNA repair. The 14 presentations by the speakers from the United States, four from the United Kingdom, one each from Italy, The Netherlands, and France, and 13 from Japan, covered most aspects of DNA repair, spanning DNA damage, molecular structures of repair enzymes, and clinical studies on inhibition of DNA repair processes. Extensive time was reserved for discussions with the active participation of the 150 invited Japanese scientists. The choice of a symposium on DNA repair in human cancers resulted in part from the excellent basic and clinical studies that have been carried out for many years in Japan, and the general lack of recognition versus the importance of DNA repair in understanding carcinogenesis. Copyright 2010 AACR.

  18. Repairing split ends: SIRT6, mono-ADP ribosylation and DNA repair

    Science.gov (United States)

    Van Meter, Michael; Mao, Zhiyong; Gorbunova, Vera; Seluanov, Andrei

    2011-01-01

    The sirtuin gene family comprises an evolutionarily ancient set of NAD+ dependent protein deacetylase and mono-ADP ribosyltransferase enzymes. Found in all domains of life, sirtuins regulate a diverse array of biological processes, including DNA repair, gene silencing, apoptosis and metabolism. Studies in multiple model organisms have indicated that sirtuins may also function to extend lifespan and attenuate age-related pathologies. To date, most of these studies have focused on the deacetylase activity of sirtuins, and relatively little is known about the other biochemical activity of sirtuins, mono-ADP ribosylation. We recently reported that the mammalian sirtuin, SIRT6, mono-ADP ribosylates PARP1 to promote DNA repair in response to oxidative stress. In this research perspective we review the role of SIRT6 in DNA repair and discuss the emerging implications for sirtuin directed mono-ADP ribosylation in aging and age-related diseases. PMID:21946623

  19. Other-Repair in Japanese Conversations Between Nonnative and Native Speakers

    OpenAIRE

    Hosoda, Yuri

    2000-01-01

    Although a preference for self-repair over other-repair has been observed in both native speaker (NS) discourse (e.g., Schegloff, Jefferson, & Sacks, 1977) and nonnative speaker (NNS) discourse (e.g., Firth, 1996), researchers note that other-repair still often occurs, especially in interactions with NNSs (e.g., Varonis & Gass, 1983). The present study examines conditions under which other-repair occurs and the response to other-repair in natural NS/NNS conversations in Japanese. Analysis of ...

  20. Progress of peripheral nerve repair

    Institute of Scientific and Technical Information of China (English)

    陈峥嵘

    2002-01-01

    Study on repair of peripheral nerve injury has been proceeding over a long period of time. With the use of microsurgery technique since 1960s,the quality of nerve repair has been greatly improved. In the past 40 years, with the continuous increase of surgical repair methods, more progress has been made on the basic research of peripheral nerve repair.

  1. Achilles tendon repair

    Science.gov (United States)

    Achilles tendon rupture-surgery; Percutaneous Achilles tendon rupture repair ... To fix your torn Achilles tendon, the surgeon will: Make a cut down the back of your heel Make several small cuts rather than one large cut ...

  2. Diaphragmatic hernia repair - slideshow

    Science.gov (United States)

    ... presentations/100014.htm Diaphragmatic hernia repair - series—Normal anatomy To use the sharing ... Overview The chest cavity includes the heart and lungs. The abdominal cavity includes the liver, the stomach, ...

  3. Eye muscle repair - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100062.htm Eye muscle repair - series—Normal anatomy To use the sharing ... the eyeball to the eye socket. The external muscles of the eye are found behind the conjunctiva. ...

  4. Tracheoesophageal fistula repair - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100103.htm Tracheoesophageal fistula repair - series—Normal anatomy To use the sharing ... Editorial team. Related MedlinePlus Health Topics Esophagus Disorders Fistulas Tracheal Disorders A.D.A.M., Inc. is ...

  5. INTERNAL REPAIR OF PIPELINES

    Energy Technology Data Exchange (ETDEWEB)

    Robin Gordon; Bill Bruce; Ian Harris; Dennis Harwig; Nancy Porter; Mike Sullivan; Chris Neary

    2004-04-12

    The two broad categories of deposited weld metal repair and fiber-reinforced composite liner repair technologies were reviewed for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Preliminary test programs were developed for both deposited weld metal repair and for fiber-reinforced composite liner repair. Evaluation trials have been conducted using a modified fiber-reinforced composite liner provided by RolaTube and pipe sections without liners. All pipe section specimens failed in areas of simulated damage. Pipe sections containing fiber-reinforced composite liners failed at pressures marginally greater than the pipe sections without liners. The next step is to evaluate a liner material with a modulus of elasticity approximately 95% of the modulus of elasticity for steel. Preliminary welding parameters were developed for deposited weld metal repair in preparation of the receipt of Pacific Gas & Electric's internal pipeline welding repair system (that was designed specifically for 559 mm (22 in.) diameter pipe) and the receipt of 559 mm (22 in.) pipe sections from Panhandle Eastern. The next steps are to transfer welding parameters to the PG&E system and to pressure test repaired pipe sections to failure. A survey of pipeline operators was conducted to better understand the needs and performance requirements of the natural gas transmission industry regarding internal repair. Completed surveys contained the following principal conclusions: (1) Use of internal weld repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, under congested intersections, and under railway crossings. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling (HDD) when a new bore must be created

  6. Pectus excavatum repair - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100035.htm Pectus excavatum repair - series—Normal anatomy To use the sharing ... Go to slide 4 out of 4 Overview Pectus excavatum is a deformity of the front of the ...

  7. Hiatal hernia repair - slideshow

    Science.gov (United States)

    ... presentations/100028.htm Hiatal hernia repair - series—Normal anatomy To use the sharing features on ... Overview The esophagus runs through the diaphragm to the stomach. It functions to carry food from the mouth ...

  8. Repairing ceramic insulating tiles

    Science.gov (United States)

    Dunn, B. R.; Laymance, E. L.

    1980-01-01

    Fused-silica tiles containing large voids or gauges are repaired without adhesives by plug insertion method. Tiles are useful in conduits for high-temperature gases, in furnaces, and in other applications involving heat insulation.

  9. Rotator cuff repair - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100229.htm Rotator cuff repair - series—Normal anatomy To use the sharing ... to slide 4 out of 4 Overview The rotator cuff is a group of muscles and tendons that ...

  10. Cleft lip repair - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100010.htm Cleft lip repair - series—Normal anatomy To use the sharing ... abnormal opening in the middle of the upper lip. A cleft palate is an opening in the roof of ...

  11. A quantum chemical perspective on (6-4) photolesion repair by photolyases

    NARCIS (Netherlands)

    Dreuw, Andreas; Faraji, Shirin

    2013-01-01

    (6-4)-Photolyases are fascinating enzymes which repair (6-4)-DNA photolesions utilizing light themselves. It is well known that upon initial photo-excitation of an antenna pigment an electron is transferred from an adjacent FADH(-) cofactor to the photolesion initiating repair, i.e. restoration of t

  12. Functions and Dynamics of DNA Repair Proteins in Mitosis and Meiosis

    NARCIS (Netherlands)

    E.J. Uringa

    2005-01-01

    textabstractMy PhD project encompassed studies on the functions of several different proteins, all involved in DNA repair, in somatic and germ-line cells. Hr6b and Rad18Sc are involved in a DNA repair mechanism called ‘Replicative Damage Bypass’ (RDB), and function as ubiquitin conjugating enzym

  13. Grey Repairable System Analysis

    Institute of Scientific and Technical Information of China (English)

    Renkuan Guo; Charles Ernie Love

    2006-01-01

    In this paper, we systematically discuss the basic concepts of grey theory, particularly the grey differential equation and its mathematical foundation, which is essentially unknown in the reliability engineering community. Accordingly,we propose a small-sample based approach to estimate repair improvement effects by partitioning system stopping times into intrinsic functioning times and repair improvement times. An industrial data set is used for illustrative purposes in a stepwise manner.

  14. DNA repair, immunosuppression, and skin cancer.

    Science.gov (United States)

    Yarosh, Daniel B

    2004-11-01

    UV radiation (UVR) produces erythema within the first 24 hours of exposure, suppression of the immune system within the first 10 days, and, for many people, over the course of decades, skin cancer. Although UVR damages many skin targets, DNA damage in the form of cyclobutane pyrimidine dimers (CPDs) is an important mediator of these sequelae. The action spectrum for erythema parallels the action spectrum for CPD formation in skin, and in the absence of repair, as in the genetic disease xeroderma pigmentosum (XP), skin cancer rates are dramatically increased. DNA repair in skin can be enhanced by the delivery of DNA repair enzymes encapsulated in liposomes. Used in this way, photoreactivation of CPDs greatly diminishes erythema and the suppression of contact hypersensitivity (CHS). UV endonucleases delivered by liposomes also prevent UV-induced suppression of delayed-type hypersensitivity. In a clinical study of patients with XP, T4 endonuclease V (T4N5) liposome lotion applied for one year reduced the rates of actinic keratosis (AK) and skin cancer compared with placebo. These results showed that strategies to increase sun protection should include measures to reduce DNA damage and increase the rate of DNA repair.

  15. Laparoscopic repair of large incisional hernias.

    Science.gov (United States)

    Parker, Harris H; Nottingham, James M; Bynoe, Raymond P; Yost, Michael J

    2002-06-01

    Incisional hernias after abdominal operations are a significant cause of long-term morbidity and have been reported to occur in 3 to 20 per cent of laparotomy incisions. Traditional primary suture closure repair is plagued with up to a 50 per cent recurrence rate. With the introduction of prosthetic mesh repair recurrence decreased, but complications with mesh placement emerged ushering in the development of laparoscopic incisional herniorrhaphy. The records of patients who underwent laparoscopic incisional hernia repair between June 1, 1995 and September 1, 2001 were reviewed. Patient demographics, hernia defect size, recurrence, operative time, and procedure-related complications were evaluated. Fifty patients (22 male and 28 female, mean age 57 years with range of 24-83) were scheduled for laparoscopic incisional hernia repair between June 1, 1995 and September 1, 2001. The average patient was obese with a mean body mass index of 35.8 kg/m2 (range 16-57 kg/m2). Two patients (4%) had primary ventral hernias. Forty-eight patients (96%) had incisional hernias with 22 (46%) of these previously repaired with prosthetic mesh. Mean defect size was 206.1 cm2 (range 48-594 cm2). The average mesh size was 510.2 cm2 (range 224-1050 cm2). Gore-Tex DualMesh and Bard Composite Mesh were used in 84 and 16 per cent of the repairs, respectively. Mean operating time was 97 minutes. There were no deaths. Complications were seen in 12 per cent patients (six occurrences) and included two small bowel enterotomies, a symptomatic seroma requiring aspirate, a mesh reaction requiring a short course of intravenous antibiotics, and trocar site pain (two patients). There were no recurrences during a mean follow-up of 41 months (range 3-74 months). We conclude that laparoscopic incisional herniorrhaphy offers a safe and effective repair for large primary and recurrent ventral hernia with low morbidity.

  16. Occult hernias and bilateral endoscopic total extraperitoneal inguinal hernia repair: is there a need for prophylactic repair? : Results of endoscopic extraperitoneal repair over a period of 10 years.

    Science.gov (United States)

    Saggar, V R; Sarangi, R

    2007-02-01

    An advantage of the endoscopic total extraperitoneal approach over the conventional hernia repair is detection of an unsuspected, asymptomatic hernia on the contralateral side. A high incidence of occult contralateral hernias has been reported in the literature. However, few studies have examined the incidence of development of a hernia on the healthy side evaluated previously during an endoscopic unilateral hernia repair. This study aims to evaluate the incidence of development of a contralateral hernia after a previous bilateral exploration. The need for a prophylactic contralateral repair is also addressed. We retrospectively reviewed the results of 822 endoscopic total extraperitoneal inguinal hernia repairs done in 634 patients over a period of 10 years from May 1993 to 2003. Incidence of hernia undetected clinically and during previous contralateral repair was assessed over a follow up period ranging from 10 to 82 months. About 7.97% of bilateral hernias were clinically occult hernias. Only 1.12% of unilateral hernia repairs (who had undergone a contralateral evaluation at surgery) subsequently developed a hernia on the other side. The endoscopic approach to inguinal hernia repair is an excellent tool to detect and treat occult contralateral hernias. The incidence of hernia occurring at the contralateral side after a previous bilateral exploration is low, hence a prophylactic repair on the contralateral side is not recommended on a routine basis.

  17. Principles of ubiquitin and SUMO modifications in DNA repair

    NARCIS (Netherlands)

    Bergink, Steven; Jentsch, Stefan

    2009-01-01

    With the discovery in the late 1980s that the DNA-repair gene RAD6 encodes a ubiquitin-conjugating enzyme, it became clear that protein modification by ubiquitin conjugation has a much broader significance than had previously been assumed. Now, two decades later, ubiquitin and its cousin SUMO are im

  18. Anhydrobiosis-associated nuclear DNA damage and repair in the sleeping chironomid: linkage with radioresistance.

    Directory of Open Access Journals (Sweden)

    Oleg Gusev

    Full Text Available Anhydrobiotic chironomid larvae can withstand prolonged complete desiccation as well as other external stresses including ionizing radiation. To understand the cross-tolerance mechanism, we have analyzed the structural changes in the nuclear DNA using transmission electron microscopy and DNA comet assays in relation to anhydrobiosis and radiation. We found that dehydration causes alterations in chromatin structure and a severe fragmentation of nuclear DNA in the cells of the larvae despite successful anhydrobiosis. Furthermore, while the larvae had restored physiological activity within an hour following rehydration, nuclear DNA restoration typically took 72 to 96 h. The DNA fragmentation level and the recovery of DNA integrity in the rehydrated larvae after anhydrobiosis were similar to those of hydrated larvae irradiated with 70 Gy of high-linear energy transfer (LET ions ((4He. In contrast, low-LET radiation (gamma-rays of the same dose caused less initial damage to the larvae, and DNA was completely repaired within within 24 h. The expression of genes encoding the DNA repair enzymes occurred upon entering anhydrobiosis and exposure to high- and low-LET radiations, indicative of DNA damage that includes double-strand breaks and their subsequent repair. The expression of antioxidant enzymes-coding genes was also elevated in the anhydrobiotic and the gamma-ray-irradiated larvae that probably functions to reduce the negative effect of reactive oxygen species upon exposure to these stresses. Indeed the mature antioxidant proteins accumulated in the dry larvae and the total activity of antioxidants increased by a 3-4 fold in association with anhydrobiosis. We conclude that one of the factors explaining the relationship between radioresistance and the ability to undergo anhydrobiosis in the sleeping chironomid could be an adaptation to desiccation-inflicted nuclear DNA damage. There were also similarities in the molecular response of the larvae to

  19. DNA base excision repair nanosystem engineering: model development.

    Science.gov (United States)

    Sokhansanj, B A

    2005-01-01

    DNA base damage results from a combination of endogenous sources, (normal metabolism, increased metabolism due to obesity, stress from diseases such as arthritis and diabetes, and ischemia) and the environment (ingested toxins, ionizing radiation, etc.). If unrepaired DNA base damage can lead to diminished cell function, and potentially diseases and eventually mutations that lead to cancer. Sophisticated DNA repair mechanisms have evolved in all living cells to preserve the integrity of inherited genetic information and transcriptional control. Understanding a system like DNA repair is greatly enhanced by using engineering methods, in particular modeling interactions and using predictive simulation to analyze the impact of perturbations. We describe the use of such a "nanosystem engineering" approach to analyze the DNA base excision repair pathway in human cells, and use simulation to predict the impact of varying enzyme concentration on DNA repair capacity.

  20. Molecular mechanisms of DNA repair inhibition by caffeine

    Energy Technology Data Exchange (ETDEWEB)

    Selby, C.P.; Sancar, A. (Univ. of North Carolina School of Medicine, Chapel Hill (USA))

    1990-05-01

    Caffeine potentiates the mutagenic and lethal effects of genotoxic agents. It is thought that this is due, at least in some organisms, to inhibition of DNA repair. However, direct evidence for inhibition of repair enzymes has been lacking. Using purified Escherichia coli DNA photolyase and (A)BC excinuclease, we show that the drug inhibits photoreactivation and nucleotide excision repair by two different mechanisms. Caffeine inhibits photoreactivation by interfering with the specific binding of photolyase to damaged DNA, and it inhibits nucleotide excision repair by promoting nonspecific binding of the damage-recognition subunit, UvrA, of (A)BC excinuclease. A number of other intercalators, including acriflavin and ethidium bromide, appear to inhibit the excinuclease by a similar mechanism--that is, by trapping the UvrA subunit in nonproductive complexes on undamaged DNA.

  1. An Overview of DNA Repair in Amyotrophic Lateral Sclerosis

    Directory of Open Access Journals (Sweden)

    Fabio Coppedè

    2011-01-01

    Full Text Available Amyotrophic lateral sclerosis (ALS, also known as motor neuron disease (MND, is an adult onset neurodegenerative disorder characterised by the degeneration of cortical and spinal cord motor neurons, resulting in progressive muscular weakness and death. Increasing evidence supports mitochondrial dysfunction and oxidative DNA damage in ALS motor neurons. Several DNA repair enzymes are activated following DNA damage to restore genome integrity, and impairments in DNA repair capabilities could contribute to motor neuron degeneration. After a brief description of the evidence of DNA damage in ALS, this paper focuses on the available data on DNA repair activity in ALS neuronal tissue and disease animal models. Moreover, biochemical and genetic data on DNA repair in ALS are discussed in light of similar findings in other neurodegenerative diseases.

  2. 2-Hydrazinobenzothiazole-based etheno-adduct repair protocol (HERP): a method for quantitative determination of direct repair of etheno-bases.

    Science.gov (United States)

    Shivange, Gururaj; Kodipelli, Naveena; Anindya, Roy

    2015-04-01

    Etheno-DNA adducts are mutagenic and lead to genomic instability. Enzymes belonging to Fe(II)/2-oxoglutarate-dependent dioxygenase family repair etheno-DNA adducts by directly removing alkyl chain as glyoxal. Presently there is no simple method to assess repair reaction of etheno-adducts. We have developed a rapid and sensitive assay for studying etheno-DNA adduct repair by Fe(II)/2-oxoglutarate-dependent dioxygenases. Using AlkB as model Fe(II)/2-oxoglutarate-dependent dioxygenases, we performed in vitro repair of etheno-adducts containing DNA and detected glyoxal by reacting with 2-hydrazinobenzothiazole which forms complex yellow color compound with distinct absorption spectrum with a peak absorption at 365 nm. We refer this method as 2-hydrazinobenzothiazole-based etheno-adduct repair protocol or HERP. Our novel approach for determining repair of etheno-adducts containing DNA overcomes several drawbacks of currently available radioisotope-based assay.

  3. When Yawning Occurs in Elephants

    Science.gov (United States)

    Rossman, Zoë T.; Hart, Benjamin L.; Greco, Brian J.; Young, Debbie; Padfield, Clare; Weidner, Lisa; Gates, Jennifer; Hart, Lynette A.

    2017-01-01

    Yawning is a widely recognized behavior in mammalian species. One would expect that elephants yawn, although to our knowledge, no one has reported observations of yawning in any species of elephant. After confirming a behavioral pattern matching the criteria of yawning in two Asian elephants (Elephas maximus) in a zoological setting, this study was pursued with nine captive African elephants (Loxodonta africana) at a private reserve in the Western Cape, South Africa, the Knysna Elephant Park. Observations were made in June–September and in December. In the daytime, handlers managed seven of the elephants for guided interactions with visitors. At night, all elephants were maintained in a large enclosure with six having limited outdoor access. With infrared illumination, the elephants were continuously recorded by video cameras. During the nights, the elephants typically had 1–3 recumbent sleeping/resting bouts, each lasting 1–2 h. Yawning was a regular occurrence upon arousal from a recumbency, especially in the final recumbency of the night. Yawning was significantly more frequent in some elephants. Yawning was rare during the daytime and during periods of standing around in the enclosure at night. In six occurrences of likely contagious yawning, one elephant yawned upon seeing another elephant yawning upon arousal from a final recumbency; we recorded the sex and age category of the participants. The generality of yawning in both African and Asian elephants in other environments was documented in video recordings from 39 zoological facilities. In summary, the study provides evidence that yawning does occur in both African and Asian elephants, and in African elephants, yawning was particularly associated with arousal from nighttime recumbencies. PMID:28293560

  4. Ceramic restoration repair: report of two cases

    Directory of Open Access Journals (Sweden)

    Luís Henrique Araújo Raposo

    2009-04-01

    Full Text Available The esthetic and functional rehabilitation of patients with multiple missing teeth can be performed with several techniques and materials. Ceramic restorations provide reliable masticatory function and good esthetics. However, fracture can occur in some cases due to their brittle behavior. In some cases, the replacement of an extensive prosthesis is a problem due to the high treatment cost. In this paper, two cases are presented, in which fractures occurred in extensive metal-ceramic fixed partial dentures, and their replacement was not possible. Ceramic repair was chosen and the sequences of treatment with and without presence of the ceramic fragment are also discussed. The cases illustrate that, in some situations, fractured metal-ceramic partial dentures can be successfully repaired when prosthetic replacement is not a choice. Prosthodontists must use alternatives that allow a reliable repair to extensive metal-ceramic fixed partial dentures. Surface preparation of the ceramic with hydrofluoric acid in conjunction with a silane coupling agent is essential for a predictable bonding of composite resin. The repair performed with composite resin is an esthetic and functional alternative when extensive fixed partial dentures cannot be replaced.

  5. The one-stage rhinoplasty septal perforation repair.

    Science.gov (United States)

    Foda, H M

    1999-08-01

    A combined septal perforation repair and rhinoplasty was performed in 20 patients (12 males, eight females; age range 16-36, mean age 29.6) presenting with septal perforations (size 1-4 cm) and external nasal deformities. The external rhinoplasty approach was used for all cases and the perforation was repaired using bilateral intranasal mucosal advancement flaps with a connective tissue interposition graft in between. The perforation was totally closed in 18 cases (90 per cent) with complete resolution of the pre-operative symptoms occurring in 16 (80 per cent). Cosmetically, 19 cases (95 per cent) were very satisfied with their aesthetic result. The exposure provided by the external approach proved to be very helpful in the process of septal perforation repair. Our results show that septal perforation repair could safely be combined with rhinoplasty and that some of the rhinoplasty manoeuvres used could even facilitate the process of septal perforation repair.

  6. Detecting and Correcting Speech Repairs

    CERN Document Server

    Heeman, P A; Heeman, Peter; Allen, James

    1994-01-01

    Interactive spoken dialog provides many new challenges for spoken language systems. One of the most critical is the prevalence of speech repairs. This paper presents an algorithm that detects and corrects speech repairs based on finding the repair pattern. The repair pattern is built by finding word matches and word replacements, and identifying fragments and editing terms. Rather than using a set of prebuilt templates, we build the pattern on the fly. In a fair test, our method, when combined with a statistical model to filter possible repairs, was successful at detecting and correcting 80\\% of the repairs, without using prosodic information or a parser.

  7. A Corpus-based Study on Self-repairs in Chinese EFL Learners' Spoken English

    Institute of Scientific and Technical Information of China (English)

    张付花

    2009-01-01

    Self-repair mentioned in this paper actually refers to self-initiated same-turn self-repair, which comprises a particular set of repair strategies in which trouble source and repairing segments occur in the same turn and the repair is beth initiated and performed by the speaker of trouble source. This study aims to study the self-repair behaviour of Chinese EFL learners based on the Spoken English Corpus of Chinese Learners as the observing corpus and the reference corpus SBNC. This study is mainly concerned with use frequency, distributions and structures of the self-repair on the basis of a clear classification of the self-repalr, aiming to find out whether there are significant differences in these three aspects of the self-repair between the Chinese EFL learners and the native speakers. Some implications and applications of the findings are also available for English teaching and learning in China.

  8. Differential repair of UV damage in Saccharomyces cerevisiae is cell cycle dependent.

    Science.gov (United States)

    Terleth, C; Waters, R; Brouwer, J; van de Putte, P

    1990-09-01

    In the yeast Saccharomyces cerevisiae the transcriptionally active MAT alpha locus is repaired preferentially to the inactive HML alpha locus after UV irradiation. Here we analysed the repair of both loci after irradiating yeast cells at different stages of the mitotic cell cycle. In all stages repair of the active MAT alpha locus occurs at a rate of 30% removal of dimers per hour after a UV dose of 60 J/m2. The inactive HML alpha is repaired as efficiently as MAT alpha following irradiation in G2 whereas repair of HML alpha is less efficient in the other stages. Thus differential repair is observed in G1 and S but not in G2. Apparently, in G2 a chromatin structure exists in which repair does not discriminate between transcriptionally active and inactive DNA or, alternatively, an additional repair mechanism might exist which is only operational during G2.

  9. Imaging and management of complications of open surgical repair of abdominal aortic aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Nayeemuddin, M. [Department of Interventional Radiology, City General Hospital, University Hospital of North Staffordshire NHS Trust, Stoke-On-Trent (United Kingdom); Pherwani, A.D. [Department of Vascular Surgery, City General Hospital, University Hospital of North Staffordshire NHS Trust, Stoke-On-Trent (United Kingdom); Asquith, J.R., E-mail: john.asquith@uhns.nhs.uk [Department of Interventional Radiology, City General Hospital, University Hospital of North Staffordshire NHS Trust, Stoke-On-Trent (United Kingdom)

    2012-08-15

    Open repair is still considered the reference standard for long-term repair of abdominal aortic aneurysms (AAA). In contrast to endovascular aneurysm repair (EVAR), patients with open surgical repair of AAA are not routinely followed up with imaging. Although complications following EVAR are widely recognized and routinely identified on follow-up imaging, complications also do occur following open surgical repair. With frequent use of multi-slice computed tomography (CT) angiography (CTA) in vascular patients, there is now improved recognition of the potential complications following open surgical repair. Many of these complications are increasingly being managed using endovascular techniques. The aim of this review is to illustrate a variety of potential complications that may occur following open surgical repair and to demonstrate their management using both surgical and endovascular techniques.

  10. Biomolecular Simulation of Base Excision Repair and Protein Signaling

    Energy Technology Data Exchange (ETDEWEB)

    Straatsma, TP; McCammon, J A; Miller, John H; Smith, Paul E; Vorpagel, Erich R; Wong, Chung F; Zacharias, Martin W

    2006-03-03

    The goal of the Biomolecular Simulation of Base Excision Repair and Protein Signaling project is to enhance our understanding of the mechanism of human polymerase-β, one of the key enzymes in base excision repair (BER) and the cell-signaling enzymes cyclic-AMP-dependent protein kinase. This work used molecular modeling and simulation studies to specifically focus on the • dynamics of DNA and damaged DNA • dynamics and energetics of base flipping in DNA • mechanism and fidelity of nucleotide insertion by BER enzyme human polymerase-β • mechanism and inhibitor design for cyclic-AMP-dependent protein kinase. Molecular dynamics simulations and electronic structure calculations have been performed using the computer resources at the Molecular Science Computing Facility at the Environmental Molecular Sciences Laboratory.

  11. Groin hernia repair in young males: mesh or sutured repair?

    DEFF Research Database (Denmark)

    Bisgaard, T; Bay-Nielsen, M; Kehlet, H

    2010-01-01

    Large-scale data for the optimal inguinal hernia repair in younger men with an indirect hernia is not available. We analysed nationwide data for risk of reoperation in younger men after a primary repair using a Lichtenstein operation or a conventional non-mesh hernia repair....

  12. Enzyme detection by microfluidics

    DEFF Research Database (Denmark)

    2013-01-01

    Microfluidic-implemented methods of detecting an enzyme, in particular a DNA-modifying enzyme, are provided, as well as methods for detecting a cell, or a microorganism expressing said enzyme. The enzyme is detected by providing a nucleic acid substrate, which is specifically targeted...... by that enzyme...

  13. Cleft lip and palate repair

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002979.htm Cleft lip and palate repair To use the sharing features on this page, please enable JavaScript. Cleft lip and cleft palate repair is surgery to fix birth defects ...

  14. Abdominal aortic aneurysm repair - open

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007392.htm Abdominal aortic aneurysm repair - open To use the sharing features on this page, please enable JavaScript. Open abdominal aortic aneurysm repair is surgery to fix a widened part ...

  15. Failure strength of repair devices versus meniscus suturing techniques.

    Science.gov (United States)

    Aşík, Mehmet; Sener, Nadir

    2002-01-01

    The purpose of this study was to compare the load to failure of different common suturing techniques with repair devices. Seventy-one calf medial menisci were cut to simulate peripheral longitudinal tears and repaired with one of 13 repair techniques. The two parts of the meniscus were pulled using the Instron tensometer until failure occurred. The techniques and repair devices tested were vertical (0 PDS, 2-0 PDS, 2-0 Ethibond), horizontal (0 PDS, 2-0 PDS, 2-0 Ethibond) suturing, T-fix, Mitek, Clearfix screw, Clearfix dart, Biostinger, S-D-sorb, and Artrex dart. The strongest repair method in our study was the vertical sutures with 0 PDS. In this study the mean failure strength of all meniscal repair devices was lower than that of the vertical and horizontal suturing techniques. All meniscus repair devices except T-fix and in some the Arthrex dart (40% broken up) pulled out of the menisci. Devices which had only horizontally placed barbs had lower mean failure strength. Failure strength of T-fix was similar to horizontal sutures with 2-0 Ethibond and 2-0 PDS. In conclusion, because all meniscal repair devices had inferior results, when such devices are used, postoperative rehabilitation should not be hastened, and their inferior primary stability should be kept in mind.

  16. Thermodynamics of the DNA damage repair steps of human 8-oxoguanine DNA glycosylase.

    Directory of Open Access Journals (Sweden)

    Nikita A Kuznetsov

    Full Text Available Human 8-oxoguanine DNA glycosylase (hOGG1 is a key enzyme responsible for initiating the base excision repair of 7,8-dihydro-8-oxoguanosine (oxoG. In this study a thermodynamic analysis of the interaction of hOGG1 with specific and non-specific DNA-substrates is performed based on stopped-flow kinetic data. The standard Gibbs energies, enthalpies and entropies of specific stages of the repair process were determined via kinetic measurements over a temperature range using the van't Hoff approach. The three steps which are accompanied with changes in the DNA conformations were detected via 2-aminopurine fluorescence in the process of binding and recognition of damaged oxoG base by hOGG1. The thermodynamic analysis has demonstrated that the initial step of the DNA substrates binding is mainly governed by energy due to favorable interactions in the process of formation of the recognition contacts, which results in negative enthalpy change, as well as due to partial desolvation of the surface between the DNA and enzyme, which results in positive entropy change. Discrimination of non-specific G base versus specific oxoG base is occurring in the second step of the oxoG-substrate binding. This step requires energy consumption which is compensated by the positive entropy contribution. The third binding step is the final adjustment of the enzyme/substrate complex to achieve the catalytically competent state which is characterized by large endothermicity compensated by a significant increase of entropy originated from the dehydration of the DNA grooves.

  17. Nanomaterials promise better bone repair

    OpenAIRE

    Qifei Wang; Jianhua Yan; Junlin Yang; Bingyun Li

    2016-01-01

    Nanomaterials mimicking the nano-features of bones and offering unique smart functions are promising for better bone fracture repair. This review provides an overview of the current state-of-the-art research in developing and using nanomaterials for better bone fracture repair. This review begins with a brief introduction of bone fracture repair processes, then discusses the importance of vascularization, the role of growth factors in bone fracture repair, and the failure of bone fracture rep...

  18. Laparoscopic repair of femoral hernia

    OpenAIRE

    Yang, Xue-Fei; Liu, Jia-Lin

    2016-01-01

    Laparoscopic repair of inguinal hernia is mini-invasive and has confirmed effects. Femoral hernia could be repaired through the laparoscopic procedures for inguinal hernia. These procedures have clear anatomic view in the operation and preoperatively undiagnosed femoral hernia could be confirmed and treated. Lower recurrence ratio was reported in laparoscopic procedures compared with open procedures for repair of femoral hernia. The technical details of laparoscopic repair of femoral hernia, ...

  19. Half-bead weld repairs for in-service applications

    Energy Technology Data Exchange (ETDEWEB)

    Holz, P.P. Sr.

    1978-01-01

    Successful half- or temper-bead technique weld repairs performed to Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code guidelines were made to two Heavy-Section Steel Technology Program vessels and a qualification prolongation. Intermediate sized vessels, equivalent in thickness to nuclear pressure vessels, were repair welded and subsequently flawed and pressure tested to approximately 2/sup 1///sub 4/ times design pressure before leakage occurred. Discussed are the standards and procedures used with half-bead repairs, resultant induced metallurgical and stress effects, flaw test criterion, pressure test details and results, and recommendations for further development work for a speedier application process.

  20. Differential repair of UV damage in Saccharomyces cerevisiae.

    Science.gov (United States)

    Terleth, C; van Sluis, C A; van de Putte, P

    1989-06-26

    Preferential repair of UV-induced damage is a phenomenon by which mammalian cells might enhance their survival. This paper presents the first evidence that preferential repair occurs in the lower eukaryote Saccharomyces cerevisiae. Moreover an unique approach is reported to compare identical sequences present on the same chromosome and only differing in expression. We determined the removal of pyrimidine dimers from two identical alpha-mating type loci and we were able to show that the active MAT alpha locus is repaired preferentially to the inactive HML alpha locus. In a sir-3 mutant, in which both loci are active this preference is not observed.

  1. Aircraft Propeller Hub Repair

    Energy Technology Data Exchange (ETDEWEB)

    Muth, Thomas R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peter, William H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-02-13

    The team performed a literature review, conducted residual stress measurements, performed failure analysis, and demonstrated a solid state additive manufacturing repair technique on samples removed from a scrapped propeller hub. The team evaluated multiple options for hub repair that included existing metal buildup technologies that the Federal Aviation Administration (FAA) has already embraced, such as cold spray, high velocity oxy-fuel deposition (HVOF), and plasma spray. In addition the team helped Piedmont Propulsion Systems, LLC (PPS) evaluate three potential solutions that could be deployed at different stages in the life cycle of aluminum alloy hubs, in addition to the conventional spray coating method for repair. For new hubs, a machining practice to prevent fretting with the steel drive shaft was recommended. For hubs that were refurbished with some material remaining above the minimal material condition (MMC), a silver interface applied by an electromagnetic pulse additive manufacturing method was recommended. For hubs that were at or below the MMC, a solid state additive manufacturing technique using ultrasonic welding (UW) of thin layers of 7075 aluminum to the hub interface was recommended. A cladding demonstration using the UW technique achieved mechanical bonding of the layers showing promise as a viable repair method.

  2. Elevated Liver Enzymes

    Science.gov (United States)

    Symptoms Elevated liver enzymes By Mayo Clinic Staff Elevated liver enzymes may indicate inflammation or damage to cells in the liver. Inflamed or ... than normal amounts of certain chemicals, including liver enzymes, into the bloodstream, which can result in elevated ...

  3. Laparoscopic Incisional Hernia Repair in Obese Patients

    Science.gov (United States)

    2005-01-01

    Background and Objectives: Laparoscopic incisional hernia repair is coming to the forefront as a preferred method of repair due to the advantages offered by minimally invasive techniques. To evaluate safety and feasibility of this approach in obese patients when performed by a general surgeon trained in basic laparoscopy with no prior experience in this technique, we reviewed our early experience in the first 18 patients. Methods: All patients with incisional hernias presenting to a single surgeon from 2000 to 2002 were offered laparoscopic repair. Patients were informed about the limited experience of the surgeon in this particular field. Those who consented were repaired laparoscopically using a standard 4-port technique, one 12-mm port and three 5-mm ports. All patients with body mass index ≥30 were included in this review. A retrospective review of the data included demographics, operative time, blood loss, hospital stay, postoperative complications, and patient satisfaction. Results: Nineteen laparoscopic repairs were completed in 18 patients. No conversions to open repair were necessary. All patients were females except for 2. All hernia sacs were left in place, some of which were empty while others required extensive lysis of adhesions to release sac contents. Mean fascial defect was 102.5 cm2. One defect was closed primarily without mesh, while the rest were closed using Composix mesh in 1 and Dual Plus Gore-Tex mesh in the rest. Three patients were discharged from the recovery room. Mean follow-up was 24 months. No wound or mesh infections occurred. Eight patients had no complications. Eight patients had asymptomatic seromas. Two patients had hematomas; none of them required drainage. One patient had nonspecific dizziness. One patient presented with bowel obstruction secondary to early recurrence (within a week). The repair was salvaged laparoscopically. Upon evaluation by telephone calls, all patients indicated extreme satisfaction with the results

  4. Component Repair Times Obtained from MSPI Data

    Energy Technology Data Exchange (ETDEWEB)

    Eide, Steven A. [Curtiss-Wright/Scietech, Ketchum, ID (United States); Cadwallader, Lee [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-05-01

    Information concerning times to repair or restore equipment to service given a failure is valuable to probabilistic risk assessments (PRAs). Examples of such uses in modern PRAs include estimation of the probability of failing to restore a failed component within a specified time period (typically tied to recovering a mitigating system before core damage occurs at nuclear power plants) and the determination of mission times for support system initiating event (SSIE) fault tree models. Information on equipment repair or restoration times applicable to PRA modeling is limited and dated for U.S. commercial nuclear power plants. However, the Mitigating Systems Performance Index (MSPI) program covering all U.S. commercial nuclear power plants provides up-to-date information on restoration times for a limited set of component types. This paper describes the MSPI program data available and analyzes the data to obtain median and mean component restoration times as well as non-restoration cumulative probability curves. The MSPI program provides guidance for monitoring both planned and unplanned outages of trains of selected mitigating systems deemed important to safety. For systems included within the MSPI program, plants monitor both train UA and component unreliability (UR) against baseline values. If the combined system UA and UR increases sufficiently above established baseline results (converted to an estimated change in core damage frequency or CDF), a “white” (or worse) indicator is generated for that system. That in turn results in increased oversight by the US Nuclear Regulatory Commission (NRC) and can impact a plant’s insurance rating. Therefore, there is pressure to return MSPI program components to service as soon as possible after a failure occurs. Three sets of unplanned outages might be used to determine the component repair durations desired in this article: all unplanned outages for the train type that includes the component of interest, only

  5. Single molecule PCR reveals similar patterns of non-homologous DSB repair in tobacco and Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Andrew H Lloyd

    Full Text Available DNA double strand breaks (DSBs occur constantly in eukaryotes. These potentially lethal DNA lesions are repaired efficiently by two major DSB repair pathways: homologous recombination and non-homologous end joining (NHEJ. We investigated NHEJ in Arabidopsis thaliana and tobacco (Nicotiana tabacum by introducing DNA double-strand breaks through inducible expression of I-SceI, followed by amplification of individual repair junction sequences by single-molecule PCR. Using this process over 300 NHEJ repair junctions were analysed in each species. In contrast to previously published variation in DSB repair between Arabidopsis and tobacco, the two species displayed similar DSB repair profiles in our experiments. The majority of repair events resulted in no loss of sequence and small (1-20 bp deletions occurred at a minority (25-45% of repair junctions. Approximately ~1.5% of the observed repair events contained larger deletions (>20 bp and a similar percentage contained insertions. Strikingly, insertion events in tobacco were associated with large genomic deletions at the site of the DSB that resulted in increased micro-homology at the sequence junctions suggesting the involvement of a non-classical NHEJ repair pathway. The generation of DSBs through inducible expression of I-SceI, in combination with single molecule PCR, provides an effective and efficient method for analysis of individual repair junctions and will prove a useful tool in the analysis of NHEJ.

  6. Single molecule PCR reveals similar patterns of non-homologous DSB repair in tobacco and Arabidopsis.

    Science.gov (United States)

    Lloyd, Andrew H; Wang, Dong; Timmis, Jeremy N

    2012-01-01

    DNA double strand breaks (DSBs) occur constantly in eukaryotes. These potentially lethal DNA lesions are repaired efficiently by two major DSB repair pathways: homologous recombination and non-homologous end joining (NHEJ). We investigated NHEJ in Arabidopsis thaliana and tobacco (Nicotiana tabacum) by introducing DNA double-strand breaks through inducible expression of I-SceI, followed by amplification of individual repair junction sequences by single-molecule PCR. Using this process over 300 NHEJ repair junctions were analysed in each species. In contrast to previously published variation in DSB repair between Arabidopsis and tobacco, the two species displayed similar DSB repair profiles in our experiments. The majority of repair events resulted in no loss of sequence and small (1-20 bp) deletions occurred at a minority (25-45%) of repair junctions. Approximately ~1.5% of the observed repair events contained larger deletions (>20 bp) and a similar percentage contained insertions. Strikingly, insertion events in tobacco were associated with large genomic deletions at the site of the DSB that resulted in increased micro-homology at the sequence junctions suggesting the involvement of a non-classical NHEJ repair pathway. The generation of DSBs through inducible expression of I-SceI, in combination with single molecule PCR, provides an effective and efficient method for analysis of individual repair junctions and will prove a useful tool in the analysis of NHEJ.

  7. Damage, DNA Repair, Aging, and Neurodegeneration

    Science.gov (United States)

    Maynard, Scott; Fang, Evandro Fei; Scheibye-Knudsen, Morten; Croteau, Deborah L.; Bohr, Vilhelm A.

    2017-01-01

    Aging in mammals is accompanied by a progressive atrophy of tissues and organs, and stochastic damage accumulation to the macromolecules DNA, RNA, proteins, and lipids. The sequence of the human genome represents our genetic blueprint, and accumulating evidence suggests that loss of genomic maintenance may causally contribute to aging. Distinct evidence for a role of imperfect DNA repair in aging is that several premature aging syndromes have underlying genetic DNA repair defects. Accumulation of DNA damage may be particularly prevalent in the central nervous system owing to the low DNA repair capacity in postmitotic brain tissue. It is generally believed that the cumulative effects of the deleterious changes that occur in aging, mostly after the reproductive phase, contribute to species-specific rates of aging. In addition to nuclear DNA damage contributions to aging, there is also abundant evidence for a causative link between mitochondrial DNA damage and the major phenotypes associated with aging. Understanding the mechanistic basis for the association of DNA damage and DNA repair with aging and age-related diseases, such as neurodegeneration, would give insight into contravening age-related diseases and promoting a healthy life span. PMID:26385091

  8. Repair technology for steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Ho; Jung, Hyun Kyu; Jung, Seung Ho; Kim, Chang Hoi; Jung, Young Moo; Seo, Yong Chil; Kim, Jung Su; Seo, Moo Hong

    2001-02-01

    The most commonly used sleeving materials are thermally treated Alloy 600 and thermally treated Alloy 690 Alloy. Currently, thermally treated Alloy 690 and Alloy 800 are being offered although Alloy 800 has not been licensed in the US. To install sleeve, joint strength, leak tightness, PWSCC resistance, evaluation on process parameter range and the effect of equipments and procedures on repair plan and radiation damage have to be investigated before sleeving. ABB CE provides three type of leak tight Alloy 690 TIG welded and PLUSS sleeve. Currently, Direct Tube Repair technique using Nd:YAG laser has been developed by ABB CE and Westinghouse. FTI has brazed and kinetic sleeve designs for recirculating steam generator and hydraulic and rolled sleeve designs for one-through steam generators. Westinghouse provides HEJ, brazed and laser welded sleeve design. When sleeve is installed in order to repair the damaged S/G tubes, it is certain that defects can be occurred due to the plastic induced stress and thermal stress. Therefore it is important to minimize the residual stress. FTI provides the electrosleeve technique as a future repair candidate using electroplating.

  9. Illustrating Enzyme Inhibition Using Gibbs Energy Profiles

    Science.gov (United States)

    Bearne, Stephen L.

    2012-01-01

    Gibbs energy profiles have great utility as teaching and learning tools because they present students with a visual representation of the energy changes that occur during enzyme catalysis. Unfortunately, most textbooks divorce discussions of traditional kinetic topics, such as enzyme inhibition, from discussions of these same topics in terms of…

  10. Lin28 enhances tissue repair by reprogramming cellular metabolism.

    Science.gov (United States)

    Shyh-Chang, Ng; Zhu, Hao; Yvanka de Soysa, T; Shinoda, Gen; Seligson, Marc T; Tsanov, Kaloyan M; Nguyen, Liem; Asara, John M; Cantley, Lewis C; Daley, George Q

    2013-11-07

    Regeneration capacity declines with age, but why juvenile organisms show enhanced tissue repair remains unexplained. Lin28a, a highly conserved RNA-binding protein expressed during embryogenesis, plays roles in development, pluripotency, and metabolism. To determine whether Lin28a might influence tissue repair in adults, we engineered the reactivation of Lin28a expression in several models of tissue injury. Lin28a reactivation improved hair regrowth by promoting anagen in hair follicles and accelerated regrowth of cartilage, bone, and mesenchyme after ear and digit injuries. Lin28a inhibits let-7 microRNA biogenesis; however, let-7 repression was necessary but insufficient to enhance repair. Lin28a bound to and enhanced the translation of mRNAs for several metabolic enzymes, thereby increasing glycolysis and oxidative phosphorylation (OxPhos). Lin28a-mediated enhancement of tissue repair was negated by OxPhos inhibition, whereas a pharmacologically induced increase in OxPhos enhanced repair. Thus, Lin28a enhances tissue repair in some adult tissues by reprogramming cellular bioenergetics. PAPERCLIP: Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Aspects of DNA repair and nucleotide pool imbalance

    Energy Technology Data Exchange (ETDEWEB)

    Holliday, R.

    1985-01-01

    Evidence that optimum repair depends on adequate pools of deoxynucleotide triphosphates (dNTPs) comes from the study of pyrimidine auxotrophs of Ustilago maydis. These strains are sensitive to UV light and X-rays, and for pyr1-1 it has been shown that the intracellular concentration of dTTP is reduced about 7-fold. The survival curve of pyr1-1 after UV-treatment, and split dose experiments with wild-type cells, provide evidence for an inducible repair mechanism, which probably depends on genetic recombination. Although inducible repair saves cellular resources, it has the disadvantage of becoming ineffective at doses which are high enough to inactivate the repressed structural gene(s) for repair enzymes. It is clear that a wide variety of repair mechanisms have evolved to remove lesions which arise either spontaneously or as a result of damage from external agents. Nevertheless, it would be incorrect to assume that all species require all possible pathways of repair. It is now well established that the accuracy of DNA and protein synthesis depends on proof-reading or editing mechanisms. Optimum accuracy levels will evolve from the balance between error avoidance in macromolecular synthesis and physiological efficiency in growth and propagation.

  12. Nanomaterials promise better bone repair

    Directory of Open Access Journals (Sweden)

    Qifei Wang

    2016-10-01

    Full Text Available Nanomaterials mimicking the nano-features of bones and offering unique smart functions are promising for better bone fracture repair. This review provides an overview of the current state-of-the-art research in developing and using nanomaterials for better bone fracture repair. This review begins with a brief introduction of bone fracture repair processes, then discusses the importance of vascularization, the role of growth factors in bone fracture repair, and the failure of bone fracture repair. Next, the review discusses the applications of nanomaterials for bone fracture repair, with a focus on the recent breakthroughs such as nanomaterials leading to precise immobilization of growth factors at the molecular level, promoting vascularization without the use of growth factors, and re-loading therapeutic agents after implantation. The review concludes with perspectives on challenges and future directions for developing nanomaterials for improved bone fracture repair.

  13. A symphony on C : orchestrating DNA repair for gene expression via cytosine modification The 2012 IMB Conference: DNA Demethylation, Repair and Beyond Institute of Molecular Biology, Mainz, Germany, 18-21 October 2012

    NARCIS (Netherlands)

    Rots, Marianne G.; Petersen-Mahrt, Svend K.

    2013-01-01

    Headline-grabbing attention has been given to DNA demethylation pathways as new epigenetic mechanisms, with reviews and hypotheses outnumbering research papers. As candidate proteins for DNA demethylation include well-known DNA repair enzymes, it was timely to join epigenetics and DNA repair experts

  14. Conservative Repair of a Chromosomal Double-Strand Break by Single-Strand DNA through Two Steps of Annealing▿ †

    OpenAIRE

    Storici, Francesca; Snipe, Joyce R.; Chan, Godwin K.; Dmitry A Gordenin; Michael A Resnick

    2006-01-01

    The repair of chromosomal double-strand breaks (DSBs) is essential to normal cell growth, and homologous recombination is a universal process for DSB repair. We explored DSB repair mechanisms in the yeast Saccharomyces cerevisiae using single-strand oligonucleotides with homology to both sides of a DSB. Oligonucleotide-directed repair occurred exclusively via Rad52- and Rad59-mediated single-strand annealing (SSA). Even the SSA domain of human Rad52 provided partial complementation for a null...

  15. DNA repair: Dynamic defenders against cancer and aging

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, Jill O.; Cooper, Priscilla K.

    2006-04-01

    (UV) component of sunlight. NER can be divided into two classes based on where the repair occurs. NER occurring in DNA that is not undergoing transcription (i.e., most of the genome) is called global genome repair (GGR or GGNER), while NER taking place in the transcribed strand of active genes is called transcription-coupled repair (TCR or TC-NER). We will explore NER in more detail below. Mismatch repair (MMR) is another type of excision repair that specifically removes mispaired bases resulting from replication errors. DNA damage can also result in breaks in the DNA backbone, in one or both strands. Single-strand breaks (SSBs) are efficiently repaired by a mechanism that shares common features with the later steps in BER. Double-strand breaks (DSBs) are especially devastating since by definition there is no intact complementary strand to serve as a template for repair, and even one unrepaired DSB can be lethal [3]. In cells that have replicated their DNA prior to cell division, the missing information can be supplied by the duplicate copy, or sister chromatid, and DSBs in these cells are faithfully repaired by homologous recombination involving the exchange of strands of DNA between the two copies. However, most cells in the body are non-dividing, and in these cells the major mechanism for repairing DSBs is by non-homologous end joining (NHEJ), which as the name implies involves joining two broken DNA ends together without a requirement for homologous sequence and which therefore has a high potential for loss of genetic information.

  16. Enzyme detection by microfluidics

    DEFF Research Database (Denmark)

    2013-01-01

    Microfluidic-implemented methods of detecting an enzyme, in particular a DNA-modifying enzyme, are provided, as well as methods for detecting a cell, or a microorganism expressing said enzyme. The enzyme is detected by providing a nucleic acid substrate, which is specifically targeted...

  17. Late repair of abductor avulsion after the transgluteal approach for hip arthroplasty.

    Science.gov (United States)

    Miozzari, Hermes H; Dora, Claudio; Clark, John M; Nötzli, Hubert P

    2010-04-01

    The abductor release sometimes does not heal after a transgluteal approach for hip arthroplasty. Factors influencing the success of subsequent repair are unclear. We used magnetic resonance imaging (MRI) to compare the condition of the gluteus medius with clinical outcome after late repair of abductor dehiscence in 12 total hip patients. Evaluation included a pain rating, gait evaluation, Trendelenburg test, strength grading, and Harris Hip Score. Most had both prerepair and postrepair MRI studies to assess the repair and to grade abductor muscle fatty degeneration. Two repairs without MRI were explored surgically. Although average pain, limp, and strength scores improved significantly, rerupture occurred in 4 subjects and fatty degeneration in the gluteus medius did not improve, even with intact repair. Nine patients were satisfied; 7 of these had an intact repair. Magnetic resonance imaging and operative observations suggest that chronic degeneration in the abductor mechanism is the major impediment to successful repair.

  18. Chronic Degeneration Leads to Poor Healing of Repaired Massive Rotator Cuff Tears in Rats.

    Science.gov (United States)

    Killian, Megan L; Cavinatto, Leonardo M; Ward, Samuel R; Havlioglu, Necat; Thomopoulos, Stavros; Galatz, Leesa M

    2015-10-01

    trabecular structure, and the repair had decreased strength, stiffness, and toughness, compared with the acute injury and repair group. Chronic degenerative changes in rotator cuff muscles, tendons, and bone led to inferior healing characteristics after repair compared with acute injuries and repair. The changes were not reversible after repair in the time course studied, consistent with clinical impressions. High retear rates after rotator cuff repair are associated with tear size and chronicity. Understanding the mechanisms behind this association may allow for targeted tissue therapy for tissue degeneration that occurs in the setting of chronic tears. © 2015 The Author(s).

  19. A novel method for monitoring functional lesion-specific recruitment of repair proteins in live cells

    Energy Technology Data Exchange (ETDEWEB)

    Woodrick, Jordan; Gupta, Suhani; Khatkar, Pooja; Dave, Kalpana; Levashova, Darya; Choudhury, Sujata; Elias, Hadi; Saha, Tapas; Mueller, Susette; Roy, Rabindra, E-mail: rr228@georgetown.edu

    2015-05-15

    Highlights: • A method of monitoring lesion-specific recruitment of proteins in vivo is described. • Recruitment of repair enzymes to abasic sites is monitored by co-localization. • Repair protein recruitment is consistent with known protein–protein relationships. • Cells demonstrated complete repair of abasic sites by 90 min. - Abstract: DNA–protein relationships have been studied by numerous methods, but a particular gap in methodology lies in the study of DNA adduct-specific interactions with proteins in vivo, which particularly affects the field of DNA repair. Using the repair of a well-characterized and ubiquitous adduct, the abasic (AP) site, as a model, we have developed a comprehensive method of monitoring DNA lesion-specific recruitment of proteins in vivo over time. We utilized a surrogate system in which a Cy3-labeled plasmid containing a single AP-site was transfected into cells, and the interaction of the labeled DNA with BER enzymes, including APE1, Polβ, LIG1, and FEN1, was monitored by immunofluorescent staining of the enzymes by Alexafluor-488-conjugated secondary antibody. The recruitment of enzymes was characterized by quantification of Cy3-Alexafluor-488 co-localization. To validate the microscopy-based method, repair of the transfected AP-site DNA was also quantified at various time points post-transfection using a real time PCR-based method. Notably, the recruitment time kinetics for each enzyme were consistent with AP-site repair time kinetics. This microscopy-based methodology is reliable in detecting the recruitment of proteins to specific DNA substrates and can be extended to study other in vivo DNA–protein relationships in any DNA sequence and in the context of any DNA structure in transfectable proliferating or quiescent cells. The method may be applied to a variety of disciplines of nucleic acid transaction pathways, including repair, replication, transcription, and recombination.

  20. DNA repair and mutagenesis of singlestranded bacteriophages

    Energy Technology Data Exchange (ETDEWEB)

    Doubleday, O.P.; Brandenburger, A.; Wagner, R. Jr.; Radman, M. (Brussels Univ. (Belgium)); Godson, G.N.

    1981-01-01

    Virtually all radiation-induced mutagenesis is believed to result from an error-prone repair activity (SOS repair) and to involve mutations occurring both at the site of radiation-induced lesions (targeted mutations) and in undamaged DNA (untargeted mutations). To examine the relative contributions of targeted and untargeted mutations to ..gamma.. and ultraviolet (UV) radiation mutagenesis we have determined the DNA sequences of 174 M13 revertant phages isolated from stocks of irradiated or unirradiated amber mutants grown in irradiated or unirradiated host bacteria. We have detected no obvious specificity of mutagenesis and find no evidence of a predominance of targeted mutations associated with either UV- or ..gamma..-irradiation of the phages or with the induction of the host SOS repair system. In particular, pyrimidine dimers do not appear to be the principal sites of UV-induced bare substitution mutagenesis, suggesting that such UV-induced mutagenesis may be untargeted or occur at sites of lesions other than pyrimidine dimers.

  1. Endovascular repair of blunt popliteal arterial injuries

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Shan; Zhang, Xiquan; Chen, Zhong; Zhu, Wei; Pan, Xiaolin [Dept. of nterventional Vascular, The 148th Hospital of Chinese People' s Liberation Army, Zibo (China); Dong, Peng; Sun, Yequan [Dept. of Medical Imaging, Weifang Medical University, Weifang (China); Qi, Deming [Dept. of Medical Imaging, Qilu Medical University, Zibo (China)

    2016-09-15

    To evaluate the feasibility and effectiveness of endovascular repair for blunt popliteal arterial injuries. A retrospective analysis of seven patients with clinical suspicion of popliteal arterial injuries that were confirmed by arteriography was performed from September 2009 to July 2014. Clinical data included demographics, mechanism of injury, type of injury, location of injury, concomitant injuries, time of endovascular procedures, time interval from trauma to blood flow restoration, instrument utilized, and follow-up. All patients were male (mean age of 35.9 ± 10.3 years). The type of lesion involved intimal injury (n = 1), partial transection (n = 2), complete transection (n = 2), arteriovenous fistula (n = 1), and pseudoaneurysm (n = 1). All patients underwent endovascular repair of blunt popliteal arterial injuries. Technical success rate was 100%. Intimal injury was treated with a bare-metal stent. Pseudoaneurysm and popliteal artery transections were treated with bare-metal stents. Arteriovenous fistula was treated with bare-metal stent and coils. No perioperative death and procedure-related complication occurred. The average follow-up was 20.9 ± 2.3 months (range 18–24 months). One patient underwent intra-arterial thrombolysis due to stent thrombosis at 18 months after the procedure. All limbs were salvaged. Stent migration, deformation, or fracture was not found during the follow-up. Endovascular repair seems to be a viable approach for patients with blunt popliteal arterial injuries, especially on an emergency basis. Endovascular repair may be effective in the short-term. Further studies are required to evaluate the long-term efficacy of endovascular repair.

  2. Repair and enumeration of injured coliforms in frozen foods.

    Science.gov (United States)

    Warseck, M; Ray, B; Speck, M L

    1973-12-01

    Two strains of Escherichia coli manifested death and repairable injury after being frozen in water or sterile foods at -20 C. The injured survivors were inhibited from forming colonies on violet red bile agar (VRBA) or deoxycholate lactose agar; this inhibition was greater when enumeration was done by the pour plate method instead of the surface or surface-overlay method. Injured cells repaired rapidly in Trypticase soy broth (TSB), and the repair was about maximum after 1 h at 25 C. When the injured cells were added to different foods and incubated at 25 C, repair also occurred; however, recovery was better and more uniform when the samples were mixed with TSB and incubated 1 h at 25 C. Cell multiplication was not evident until after 90 to 120 min at 25 C. The enumeration of coliforms from commercially frozen foods was increased when the thawed samples were mixed with TSB and the cells were allowed to repair 1 h at 25 C. In some samples, the repair permitted at least a 20-fold increase in the coliform count. The associated flora in the commercially frozen foods gave no evidence of impairing the repair of coliforms, nor did they start multiplication prior to 90 min after being incubated in TSB at 25 C. Generally, the plating gave more reproducible recovery of coliforms than did the most probable number method. Also, a higher number of coliforms were obtained by the surface-overlay method of plating using VRBA.

  3. DNA Repair Systems: Guardians of the Genome

    Indian Academy of Sciences (India)

    2016-10-01

    The 2015 Nobel Prize in Chemistry was awarded jointly to Tomas Lindahl, Paul Modrich and Aziz Sancar to honour their accomplishments in the field of DNA repair. Ever since the discovery of DNA structure and their importance in the storage of genetic information, questions about their stability became pertinent. A molecule which is crucial for the development and propagation of an organism must be closely monitored so that the genetic information is not corrupted. Thanks to the pioneering research work of Lindahl, Sancar, Modrich and their colleagues, we now have an holistic awareness of how DNA damage occurs and how the damage is rectified in bacteria as well as in higher organisms including human beings. A comprehensive understanding of DNA repair has proven crucial in the fight against cancer and other debilitating diseases.

  4. DNA repair in neurons: So if they don't divide what's to repair?

    Energy Technology Data Exchange (ETDEWEB)

    Fishel, Melissa L. [Department of Pediatrics (Section of Hematology/Oncology), Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202 (United States); Vasko, Michael R. [Department of Pharmacology and Toxicology, Indiana University School of Medicine, 1044 W. Walnut St., Indianapolis, IN 46202 (United States); Kelley, Mark R. [Department of Pediatrics (Section of Hematology/Oncology), Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202 (United States) and Department of Pharmacology and Toxicology, Indiana University School of Medicine, 1044 W. Walnut St., Indianapolis, IN 46202 (United States) and Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202 (United States)]. E-mail: mkelley@iupui.edu

    2007-01-03

    Neuronal DNA repair remains one of the most exciting areas for investigation, particularly as a means to compare the DNA repair response in mitotic (cancer) vs. post-mitotic (neuronal) cells. In addition, the role of DNA repair in neuronal cell survival and response to aging and environmental insults is of particular interest. DNA damage caused by reactive oxygen species (ROS) such as generated by mitochondrial respiration includes altered bases, abasic sites, and single- and double-strand breaks which can be prevented by the DNA base excision repair (BER) pathway. Oxidative stress accumulates in the DNA of the human brain over time especially in the mitochondrial DNA (mtDNA) and is proposed to play a critical role in aging and in the pathogenesis of several neurological disorders including Parkinson's disease, ALS, and Alzheimer's diseases. Because DNA damage accumulates in the mtDNA more than nuclear DNA, there is increased interest in DNA repair pathways and the consequence of DNA damage in the mitochondria of neurons. The type of damage that is most likely to occur in neuronal cells is oxidative DNA damage which is primarily removed by the BER pathway. Following the notion that the bulk of neuronal DNA damage is acquired by oxidative DNA damage and ROS, the BER pathway is a likely area of focus for neuronal studies of DNA repair. BER variations in brain aging and pathology in various brain regions and tissues are presented. Therefore, the BER pathway is discussed in greater detail in this review than other repair pathways. Other repair pathways including direct reversal, nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination and non-homologous end joining are also discussed. Finally, there is a growing interest in the role that DNA repair pathways play in the clinical arena as they relate to the neurotoxicity and neuropathy associated with cancer treatments. Among the numerous side effects of cancer treatments, major

  5. Alternative mechanisms of telomere lengthening: Permissive mutations, DNA repair proteins and tumorigenic progression

    Energy Technology Data Exchange (ETDEWEB)

    Gocha, April Renee Sandy; Harris, Julia [Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210 (United States); Groden, Joanna, E-mail: joanna.groden@osumc.edu [Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210 (United States)

    2013-03-15

    Highlights: ► Neoplastic cells maintain telomeres by telomerase or ALT. ► Genetic mutations in p53, ATRX, DAXX or H3F3A may activate ALT. ► Many DNA repair proteins are involved in ALT. ► Tumor progression is favored by telomerase expression. - Abstract: Telomeres protect chromosome termini to maintain genomic stability and regulate cellular lifespan. Maintenance of telomere length is required for neoplastic cells after the acquisition of mutations that deregulate cell cycle control and increase cellular proliferation, and can occur through expression of the enzyme telomerase or in a telomerase-independent manner termed alternative lengthening of telomeres (ALT). The precise mechanisms that govern the activation of ALT or telomerase in tumor cells are unknown, although cellular origin may favor one or the other mechanisms. ALT pathways are incompletely understood to date; however, recent publications have increasingly broadened our understanding of how ALT is activated, how it proceeds, and how it influences tumor growth. Specific mutational events influence ALT activation, as mutations in genes that suppress recombination and/or alterations in the regulation of telomerase expression are associated with ALT. Once engaged, ALT uses DNA repair proteins to maintain telomeres in the absence of telomerase; experiments that manipulate the expression of specific proteins in cells using ALT are illuminating some of its mechanisms. Furthermore, ALT may influence tumor growth, as experimental and clinical data suggest that telomerase expression may favor tumor progression. This review summarizes recent findings in mammalian cells and models, as well as clinical data, that identify the genetic mutations permissive to ALT, the DNA repair proteins involved in ALT mechanisms and the importance of telomere maintenance mechanisms for tumor progression. A comprehensive understanding of the mechanisms that permit tumor cell immortalization will be important for identifying

  6. Laparoscopic Repair of Morgagni Hernia

    Directory of Open Access Journals (Sweden)

    ilker murat arer

    2015-03-01

    Full Text Available Morgagni hernia is a congenital herniation of abdominal contents into the thoracic cavity through a retrosternal diaphragmatic defect and make up about 1 % - 5 % of all types of congenital diaphragmatic hernias. Surgical repair of Morgagni hernias is usually indicated when patients are symptomatic and have a high risk of strangulation or incarceration of the contained viscera. 71-year-old male patient admitted to emergency department with a 2-day history of abdominal pain, vomiting and obstipation. Laparoscopic repair for Morgagni hernia was performed. Laparoscopic repair for Morgagni hernia with mesh repair is secure, satisfactory and easily performed. [Cukurova Med J 2015; 40(Suppl 1: 71-74

  7. Inducible error-prone repair in B. subtilis. Final report, September 1, 1979-June 30, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Yasbin, R. E.

    1981-06-01

    The research performed under this contract has been concentrated on the relationship between inducible DNA repair systems, mutagenesis and the competent state in the gram positive bacterium Bacillus subtilis. The following results have been obtained from this research: (1) competent Bacillus subtilis cells have been developed into a sensitive tester system for carcinogens; (2) competent B. subtilis cells have an efficient excision-repair system, however, this system will not function on bacteriophage DNA taken into the cell via the process of transfection; (3) DNA polymerase III is essential in the mechanism of the process of W-reactivation; (4) B. subtilis strains cured of their defective prophages have been isolated and are now being developed for gene cloning systems; (5) protoplasts of B. subtilis have been shown capable of acquiring DNA repair enzymes (i.e., enzyme therapy); and (6) a plasmid was characterized which enhanced inducible error-prone repair in a gram positive organism.

  8. Combinatorial Reliability and Repair

    Science.gov (United States)

    1992-07-01

    Press, Oxford, 1987. [2] G. Gordon and L. Traldi, Generalized activities and the Tutte polynomial , Discrete Math. 85 (1990), 167-176. [3] A. B. Huseby, A...particular, Satyanarayana and Tindell introduced a notion of (K,j)-domination in their study of a K-terminal version of the chromatic polynomial [6], and it...G)) graphs. He also intends to look into the properties of the polynomial that gives the expected number of needed repairs of a K-terminal network

  9. Mammalian mismatch repair

    DEFF Research Database (Denmark)

    Pena Diaz, Javier; Jiricny, Josef

    2012-01-01

    A considerable surge of interest in the mismatch repair (MMR) system has been brought about by the discovery of a link between Lynch syndrome, an inherited predisposition to cancer of the colon and other organs, and malfunction of this key DNA metabolic pathway. This review focuses on recent...... advances in our understanding of the molecular mechanisms of canonical MMR, which improves replication fidelity by removing misincorporated nucleotides from the nascent DNA strand. We also discuss the involvement of MMR proteins in two other processes: trinucleotide repeat expansion and antibody maturation...

  10. DNA replication, repair, and repair tests. [Rat; human leukocytes

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, B.

    1980-09-01

    The rate of inhibition and recovery of DNA synthesis can be used in a rapid assay system to detect genotoxic potentials of chemicals. Also, the observation that an agent stimulates DNA repair in a test system indicates its ability to cause damage in DNA. Different experimental approaches to the study of repair synthesis are discussed.

  11. Formaldehyde catabolism is essential in cells deficient for the Fanconi anemia DNA-repair pathway.

    Science.gov (United States)

    Rosado, Ivan V; Langevin, Frédéric; Crossan, Gerry P; Takata, Minoru; Patel, Ketan J

    2011-11-13

    Metabolism is predicted to generate formaldehyde, a toxic, simple, reactive aldehyde that can damage DNA. Here we report a synthetic lethal interaction in avian cells between ADH5, encoding the main formaldehyde-detoxifying enzyme, and the Fanconi anemia (FA) DNA-repair pathway. These results define a fundamental role for the combined action of formaldehyde catabolism and DNA cross-link repair in vertebrate cell survival.

  12. Biologics for tendon repair.

    Science.gov (United States)

    Docheva, Denitsa; Müller, Sebastian A; Majewski, Martin; Evans, Christopher H

    2015-04-01

    Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic options used to repair ruptured tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored tendons do not recover their complete strength and functionality. Unfortunately, our understanding of tendon biology lags far behind that of other musculoskeletal tissues, thus impeding the development of new treatment options for tendon conditions. Hence, in this review, after introducing the clinical significance of tendon diseases and the present understanding of tendon biology, we describe and critically assess the current strategies for enhancing tendon repair by biological means. These consist mainly of applying growth factors, stem cells, natural biomaterials and genes, alone or in combination, to the site of tendon damage. A deeper understanding of how tendon tissue and cells operate, combined with practical applications of modern molecular and cellular tools could provide the long awaited breakthrough in designing effective tendon-specific therapeutics and overall improvement of tendon disease management.

  13. Kvitebjoern gas pipeline repair - baptism of remote pipeline repair system

    Energy Technology Data Exchange (ETDEWEB)

    Gjertveit, Erling

    2010-07-01

    On the 1st of November 2007, severe anchor damage was discovered on the 30 inch Kvitebjoern gas export pipeline. The damage constituted a localised dent and a 17deg buckle, but no leakage. Statoil has invested in building an effective repair contingency structure for the large pipeline network on the Norwegian Continental shelf, with particular focus on the large gas export pipelines. The repair method for the Kvitebjoern pipeline was remotely operated using two Morgrip couplings and a spool. The installation used the purpose built Pipeline Repair System stored at Killingoey and couplings produced and tested back in 2005. This presentation will cover the initial damage investigations, the temporary operational phase, the repair preparations, the actual repair and lessons learned. (Author)

  14. A porous polymer scaffold for meniscal lesion repair--a study in dogs.

    NARCIS (Netherlands)

    Tienen, Tony van; Heijkants, R.G.J.C.; Buma, P.; Groot, J.H. de; Pennings, A.J.; Veth, R.P.H.

    2003-01-01

    Meniscal lesions often occur in the avascular area of the meniscus with little chance of spontaneous repair. An access channel in the meniscal tissue can function as an entrance for ingrowing repair tissue from the vascular periphery of the meniscus to the lesion in the avascular zone which again in

  15. A porous polymer scaffold for meniscal lesion repair - A study in dogs

    NARCIS (Netherlands)

    Tienen, TG; Heijkants, RGJC; Buma, P; De Groot, JH; Pennings, AJ; Veth, RPH

    2003-01-01

    Meniscal lesions often occur in the avascular area of the meniscus with little chance of spontaneous repair. An access channel in the meniscal tissue can function as an entrance for ingrowing repair tissue from the vascular periphery of the meniscus to the lesion in the avascular zone which again in

  16. The body as a resource for other-initiation of repair

    DEFF Research Database (Denmark)

    Mortensen, Kristian

    2016-01-01

    This paper analyses how the human body serves as a resource for other initiation of repair. It describes how a hand gesture, a cupped hand behind the ear, is oriented to as a repair initiation in a foreign language classroom. The gesture typically occurs in the absence of speech and is treated...

  17. Naturally occurring soil salinity does not reduce N-transforming enzymes or organisms

    Science.gov (United States)

    Soil salinity can negatively affect plant production and important biogeochemical cycles which are mainly carried out by soil microbes. The objective of this study was to contribute new information on soil biological N transformations by examining the impact primary salinity reduction has on a) the ...

  18. A hydrogel-based enzyme-loaded polymersome reactor

    NARCIS (Netherlands)

    Hoog, de Hans-Peter; Arends, Isabel W.C.E.; Rowan, Alan E.; Cornelissen, Jeroen J.L.M.; Nolte, Roeland J.M.

    2010-01-01

    In this study we report the immobilization of enzyme-containing polymersomes into a macromolecular hydrogel. Whereas free enzyme shows progressive leakage from the hydrogel in a period of days, leakage of the polymersome-protected enzyme is virtually absent. The preparation of the hydrogel occurs un

  19. A hydrogel-based enzyme-loaded polymersome reactor

    NARCIS (Netherlands)

    de Hoog, H.P.M.; de Hoog, Hans-Peter; Arends, Isabel W.C.E.; Rowan, Alan E.; Cornelissen, Jeroen Johannes Lambertus Maria; Nolte, Roeland J.M.

    2010-01-01

    In this study we report the immobilization of enzyme-containing polymersomes into a macromolecular hydrogel. Whereas free enzyme shows progressive leakage from the hydrogel in a period of days, leakage of the polymersome-protected enzyme is virtually absent. The preparation of the hydrogel occurs

  20. On-bead fluorescent DNA nanoprobes to analyze base excision repair activities

    Energy Technology Data Exchange (ETDEWEB)

    Gines, Guillaume; Saint-Pierre, Christine; Gasparutto, Didier, E-mail: didier.gasparutto@cea.fr

    2014-02-17

    Graphical abstract: -- Highlights: •On magnetic beads fluorescent enzymatic assays. •Simple, easy, non-radioactive and electrophoresis-free functional assay. •Lesion-containing hairpin DNA probes are selective for repair enzymes. •The biosensing platform allows the measurement of DNA repair activities from purified enzymes or within cell free extracts. -- Abstract: DNA integrity is constantly threatened by endogenous and exogenous agents that can modify its physical and chemical structure. Changes in DNA sequence can cause mutations sparked by some genetic diseases or cancers. Organisms have developed efficient defense mechanisms able to specifically repair each kind of lesion (alkylation, oxidation, single or double strand break, mismatch, etc). Here we report the adjustment of an original assay to detect enzymes’ activity of base excision repair (BER), that supports a set of lesions including abasic sites, alkylation, oxidation or deamination products of bases. The biosensor is characterized by a set of fluorescent hairpin-shaped nucleic acid probes supported on magnetic beads, each containing a selective lesion targeting a specific BER enzyme. We have studied the DNA glycosylase alkyl-adenine glycosylase (AAG) and the human AP-endonuclease (APE1) by incorporating within the DNA probe a hypoxanthine lesion or an abasic site analog (tetrahydrofuran), respectively. Enzymatic repair activity induces the formation of a nick in the damaged strand, leading to probe's break, that is detected in the supernatant by fluorescence. The functional assay allows the measurement of DNA repair activities from purified enzymes or in cell-free extracts in a fast, specific, quantitative and sensitive way, using only 1 pmol of probe for a test. We recorded a detection limit of 1 μg mL{sup −1} and 50 μg mL{sup −1} of HeLa nuclear extracts for APE1 and AAG enzymes, respectively. Finally, the on-bead assay should be useful to screen inhibitors of DNA repair

  1. Base excision repair activities differ in human lung cancer cells and corresponding normal controls

    DEFF Research Database (Denmark)

    Karahalil, Bensu; Bohr, Vilhelm A; De Souza-Pinto, Nadja C

    2010-01-01

    Oxidative damage to DNA is thought to play a role in carcinogenesis by causing mutations, and indeed accumulation of oxidized DNA bases has been observed in samples obtained from tumors but not from surrounding tissue within the same patient. Base excision repair (BER) is the main pathway...... for the repair of oxidized modifications both in nuclear and mitochondrial DNA. In order to ascertain whether diminished BER capacity might account for increased levels of oxidative DNA damage in cancer cells, the activities of BER enzymes in three different lung cancer cell lines and their non......-cancerous counterparts were measured using oligonucleotide substrates with single DNA lesions to assess specific BER enzymes. The activities of four BER enzymes, OGG1, NTH1, UDG and APE1, were compared in mitochondrial and nuclear extracts. For each specific lesion, the repair activities were similar among the three...

  2. A Case of Microangiopathic Hemolytic Anemia after Myxoma Excision and Mitral Valve Repair Presenting as Hemolytic Uremic Syndrome

    OpenAIRE

    Park, Young Joo; Kim, Sang Pil; Shin, Ho-Jin; Choi, Jung Hyun

    2016-01-01

    Microangiopathic hemolytic anemia occurs in a diverse group of disorders, including thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, and prosthetic cardiac valves. Hemolytic anemia also occurs as a rare complication after mitral valve repair. In this report, we describe a case of microangiopathic hemolytic anemia following myxoma excision and mitral valve repair, which was presented as hemolytic uremic syndrome.

  3. Enzyme inhibition by iminosugars

    DEFF Research Database (Denmark)

    López, Óscar; Qing, Feng-Ling; Pedersen, Christian Marcus

    2013-01-01

    Imino- and azasugar glycosidase inhibitors display pH dependant inhibition reflecting that both the inhibitor and the enzyme active site have groups that change protonation state with pH. With the enzyme having two acidic groups and the inhibitor one basic group, enzyme-inhibitor complexes...

  4. Handbook of adhesive bonded structural repair

    CERN Document Server

    Wegman, Raymond F

    1992-01-01

    Provides repair methods for adhesive bonded and composite structures; identifies suitable materials and equipment for repairs; describes damage evaluation criteria and techniques, and methods of inspection before and after repair.

  5. Clamp wins pipe repair prize

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2001-04-01

    This paper describes the permanent pipeline repair system, developed by Tekmar, which is powered by seawater hydraulics and is easily installed and tested by any workclass remotely operated vehicle (rov). Details are given of the two main components of the system, namely, the diverless high pressure split repair clamp and the rov-operated tool to install it.

  6. Nucleotide excision repair in yeast

    NARCIS (Netherlands)

    Eijk, Patrick van

    2012-01-01

    Nucleotide Excision Repair (NER) is a conserved DNA repair pathway capable of removing a broad spectrum of DNA damage. In human cells a defect in NER leads to the disorder Xeroderma pigmentosum (XP). The yeast Saccharomyces cerevisiae is an excellent model organism to study the mechanism of NER. The

  7. DNA double strand break repair, chromosome synapsis and transcriptional silencing in meiosis.

    Science.gov (United States)

    Inagaki, Akiko; Schoenmakers, Sam; Baarends, Willy M

    2010-05-16

    Chromosome pairing and synapsis during meiotic prophase requires the formation and repair of DNA double-strand breaks (DSBs) by the topoisomerase-like enzyme SPO11. Chromosomes, or chromosomal regions, that lack a pairing partner, such as the largely heterologous X and Y chromosomes, show delayed meiotic DSB repair and are transcriptionally silenced. Herein, we review meiosis-specific aspects of DSB repair in relation to homology recognition and meiotic silencing of heterologous regions. We propose a dynamic interplay between progression of synapsis and persistent meiotic DSBs. Signaling from these persistent breaks could inhibit heterologous synapsis and stimulate meiotic silencing of the X and Y chromosomes.

  8. Disruption of Maternal DNA Repair Increases Sperm-DerivedChromosomal Aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, Francesco; Essers, Jeroun; Kanaar, Roland; Wyrobek,Andrew J.

    2007-02-07

    The final weeks of male germ cell differentiation occur in aDNA repair-deficient environment and normal development depends on theability of the egg to repair DNA damage in the fertilizing sperm. Geneticdisruption of maternal DNA double-strand break repair pathways in micesignificantly increased the frequency of zygotes with chromosomalstructural aberrations after paternal exposure to ionizing radiation.These findings demonstrate that radiation-induced DNA sperm lesions arerepaired after fertilization by maternal factors and suggest that geneticvariation in maternal DNA repair can modulate the risk of early pregnancylosses and of children with chromosomal aberrations of paternalorigin.

  9. Functional Analysis of Homologous Recombination Repair Proteins HerA and NurA in the Thermophile Sulfolobus islandicus

    DEFF Research Database (Denmark)

    Huang, Qihong

    A number of DNA lesions are generated in each cell every day, among which double-stranded breaks (DSBs) constitute one of the most detrimental types of DNA damage. DSBs lead to genome instability, cell death, or even tumorigenesis in human, if not repaired timely. Two main pathways are known...... for DSB repair, homologous recombination repair (HRR) and Non-homologous end joint (NHEJ). HR repairs DSBs using a homologous DNA molecule as a template resulting in error free DNA repair, whereas NHEJ promotes direct re-ligation of the broken DNA ends in an error-prone manner. In eukaryotes DSBs occurred...

  10. Reward optimization of a repairable system

    Energy Technology Data Exchange (ETDEWEB)

    Castro, I.T. [Departamento de Matematicas, Facultad de Veterinaria, Universidad de Extremadura, Avenida de la Universidad, s/n. 10071 Caceres (Spain)]. E-mail: inmatorres@unex.es; Perez-Ocon, R. [Departamento de Estadistica e Investigacion Operativa, Facultad de Ciencias, Universidad de Granada, Avenida de Severo Ochoa, s/n. 18071 Granada (Spain)]. E-mail: rperezo@ugr.es

    2006-03-15

    This paper analyzes a system subject to repairable and non-repairable failures. Non-repairable failures lead to replacement of the system. Repairable failures, first lead to repair but they lead to replacement after a fixed number of repairs. Operating and repair times follow phase type distributions (PH-distributions) and the pattern of the operating times is modelled by a geometric process. In this context, the problem is to find the optimal number of repairs, which maximizes the long-run average reward per unit time. To this end, the optimal number is determined and it is obtained by efficient numerical procedures.

  11. Wound repair in Pocillopora

    Science.gov (United States)

    Rodríguez-Villalobos, Jenny Carolina; Work, Thierry M.; Calderon-Aguileraa, Luis Eduardo

    2016-01-01

    Corals routinely lose tissue due to causes ranging from predation to disease. Tissue healing and regeneration are fundamental to the normal functioning of corals, yet we know little about this process. We described the microscopic morphology of wound repair in Pocillopora damicornis. Tissue was removed by airbrushing fragments from three healthy colonies, and these were monitored daily at the gross and microscopic level for 40 days. Grossly, corals healed by Day 30, but repigmentation was not evident at the end of the study (40 d). On histology, from Day 8 onwards, tissues at the lesion site were microscopically indistinguishable from adjacent normal tissues with evidence of zooxanthellae in gastrodermis. Inflammation was not evident. P. damicornis manifested a unique mode of regeneration involving projections of cell-covered mesoglea from the surface body wall that anastomosed to form gastrovascular canals.

  12. Groin hernia repair

    DEFF Research Database (Denmark)

    Kehlet, Henrik; Aasvang, Eske

    2005-01-01

    The choice of anesthesia for groin hernia repair is between general, regional (epidural or spinal), and local anesthesia. Existing data from large consecutive patient series and randomized studies have shown local anesthesia to be the method of choice because it can be performed by the surgeon......, does not necessarily require an attending anesthesiologist, translates into the shortest recovery (bypassing the postanesthesia care unit), has the lowest cost, and has the lowest postoperative morbidity regarding risk of urinary retention. Spinal anesthesia has no documented benefits for this small...... scientific data to support the choice of anesthesia, large epidemiologic and nationwide information from databases show an undesirable high (about 10-20%) use of spinal anesthesia and low (about 10%) use of local infiltration anesthesia. Surgeons and anesthesiologists should therefore adjust their anesthesia...

  13. Repair Sequences in American Learners of German Interlanguage

    Science.gov (United States)

    Wisbey, Evelyn

    2010-01-01

    This study in Conversation Analysis investigates the organization of other-initiated repair sequences in American learners of German, i.e., it examines how learners deal with troubles in hearing or understanding that they encounter in naturally-occurring talk-in-interaction. Data for the project were collected during informal interaction in…

  14. Repair of damaged supraglottic airway devices: A novel method

    Directory of Open Access Journals (Sweden)

    Kapoor Dheeraj

    2010-06-01

    Full Text Available Abstract Damage of laryngeal mask airway and other supraglottic airway devices has always been a matter of concern. Although manufacturer recommends maximum 40 uses of LMA (and its congeners but damage before 40 uses needs to be evaluated. We hereby, describe a novel method of repair of supraglottic devices when damage occurs at mask inflation line or pilot balloon valve assembly.

  15. Scrape on Endeavour's robotic arm during oxygen leak repairs

    Science.gov (United States)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- Robotic arm experts get ready for ultrasound testing on Endeavour's robotic arm. A scrape of the honeycomb shell around the arm occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of Endeavour on mission STS-113 has been postponed until no earlier than Nov. 22.

  16. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A. Jolt; Blom, Paul W.m.; Michels, Jasper J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium

  17. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A. Jolt; Blom, Paul W.m.; Michels, Jasper J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypo

  18. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A.J.; Blom, P.W.M.; Michels, J.J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypo

  19. Augmented Versus Nonaugmented Repair of Acute Achilles Tendon Rupture: A Systematic Review and Meta-analysis.

    Science.gov (United States)

    Zhang, Yi-Jun; Zhang, Chi; Wang, Quan; Lin, Xiang-Jin

    2017-04-01

    Although simple end-to-end repair of the Achilles tendon is common, many augmented repair protocols have been implemented for acute Achilles tendon rupture. However, whether augmented repair is better than nonaugmented repair of an acute Achilles tendon rupture is still unknown. To conduct a meta-analysis to determine whether augmented surgical repair of an acute Achilles tendon rupture improved subjective patient satisfaction without an increase in rerupture rates. Secondary outcomes assessed included infections, ankle range of motion, calf muscle strength, and minor complications. Meta-analysis. A systematic literature search of peer-reviewed articles was conducted to identify all randomized controlled trials (RCTs) comparing augmented repair and nonaugmented repair for acute Achilles tendon rupture from January 1980 to August 2016 in the electronic databases of PubMed, Web of Science (SCI-E/SSCI/A&HCI), and EMBASE. The keywords (Achilles tendon rupture) AND (surg* OR operat* OR repair* OR augment* OR non-augment* OR end-to-end OR sutur*) were combined, and results were limited to human RCTs and controlled clinical trials published in the English language. Four RCTs involving 169 participants were eligible for inclusion; 83 participants were treated with augmented repair and 86 were treated with nonaugmented repair. Augmented repair led to similar responses when compared with nonaugmented repair for acute Achilles tendon rupture (93% vs 90%, respectively; P = .53). The rerupture rates showed no significant difference for augmented versus nonaugmented repair (7.2% vs 9.3%, respectively; P = .69). No differences in superficial and deep infections occurred in augmented (7 infections) and nonaugmented (8 infections) repair groups during postoperative follow-up ( P = .89). The average incisional infection rate was 8.4% with augmented repair and 9.3% with nonaugmented repair. No significant differences in other complications were found between augmented (7.2%) and

  20. Transcript-RNA-templated DNA recombination and repair.

    Science.gov (United States)

    Keskin, Havva; Shen, Ying; Huang, Fei; Patel, Mikir; Yang, Taehwan; Ashley, Katie; Mazin, Alexander V; Storici, Francesca

    2014-11-20

    Homologous recombination is a molecular process that has multiple important roles in DNA metabolism, both for DNA repair and genetic variation in all forms of life. Generally, homologous recombination involves the exchange of genetic information between two identical or nearly identical DNA molecules; however, homologous recombination can also occur between RNA molecules, as shown for RNA viruses. Previous research showed that synthetic RNA oligonucleotides can act as templates for DNA double-strand break (DSB) repair in yeast and human cells, and artificial long RNA templates injected in ciliate cells can guide genomic rearrangements. Here we report that endogenous transcript RNA mediates homologous recombination with chromosomal DNA in yeast Saccharomyces cerevisiae. We developed a system to detect the events of homologous recombination initiated by transcript RNA following the repair of a chromosomal DSB occurring either in a homologous but remote locus, or in the same transcript-generating locus in reverse-transcription-defective yeast strains. We found that RNA-DNA recombination is blocked by ribonucleases H1 and H2. In the presence of H-type ribonucleases, DSB repair proceeds through a complementary DNA intermediate, whereas in their absence, it proceeds directly through RNA. The proximity of the transcript to its chromosomal DNA partner in the same locus facilitates Rad52-driven homologous recombination during DSB repair. We demonstrate that yeast and human Rad52 proteins efficiently catalyse annealing of RNA to a DSB-like DNA end in vitro. Our results reveal a novel mechanism of homologous recombination and DNA repair in which transcript RNA is used as a template for DSB repair. Thus, considering the abundance of RNA transcripts in cells, RNA may have a marked impact on genomic stability and plasticity.

  1. Directed Evolution of Enzymes for Industrial Biocatalysis.

    Science.gov (United States)

    Porter, Joanne L; Rusli, Rukhairul A; Ollis, David L

    2016-02-01

    Enzymes have the potential to catalyse a wide variety of chemical reactions. They are increasingly being sought as environmentally friendly and cost-effective alternatives to conventional catalysts used in industries ranging from bioremediation to applications in medicine and pharmaceutics. Despite the benefits, they are not without their limitations. Many naturally occurring enzymes are not suitable for use outside of their native cellular environments. However, protein engineering can be used to generate enzymes tailored for specific industrial applications. Directed evolution is particularly useful and can be employed even when lack of structural information impedes the use of rational design. The aim of this review is to provide an overview of current industrial applications of enzyme technology and to show how directed evolution can be used to modify and to enhance enzyme properties. This includes a brief discussion on library generation and a more detailed focus on library screening methods, which are critical to any directed evolution experiment.

  2. Analysis of failed rotator cuff repair – Retrospective survey of revisions after open rotator cuff repair

    Directory of Open Access Journals (Sweden)

    Rupert Schupfner

    2017-07-01

    Full Text Available Background Rotator cuff defects are frequently occurring shoulder pathologies associated with pain and movement impairment. Aims The aim of the study was to analyse the pathologies that lead to operative revisions after primary open rotator cuff repair. Methods In 216 patients who underwent primary rotator cuff repair and later required operative revision between 1996 to 2005, pathologies found intraoperatively during the primary operation and during revision surgery were collected, analysed and compared. Results The average age at the time of revision surgery was 54.3 years. The right shoulder (61.6 per cent was more often affected than the left, males (63.4 per cent more often than females. At primary operation – apart from rotator cuff repair – there were the following surgical procedures performed: 190 acromioplasty, 86 Acromiclavicular joint resections, 68 tenodesis, 40 adhesiolysis and 1 tenotomy. If an ACJ-resection had been performed in the primary operation, ACJ-problems were rare in revision surgery (p<0.01. Primary gleno-humeral adhesions were associated with a significant rise in re-tearing rate (p=0.049. Primary absence of adhesions went along with a significant lower rate of adhesions found at revision (p=0.018. Primary performed acromioplasty had no influence on re-tearing rate (p=0.408 or on the rate of subacromial impingement at revision surgery (p=0.709. Conclusion To avoid operative revision after rotator cuff repair relevant copathologies of the shoulder have to be identified before or during operation and treated accordingly. Therefore, even during open rotator cuff repair, the surgeon should initially start with arthroscopy of the shoulder joint and subacromial space to recognise co-pathologies.

  3. Repair of Chronic Achilles Ruptures Has a High Incidence of Venous Thromboembolism.

    Science.gov (United States)

    Bullock, Mark J; DeCarbo, William T; Hofbauer, Mark H; Thun, Joshua D

    2016-11-23

    Background Despite the low incidence of deep vein thrombosis (DVT) in foot and ankle surgery, some authors report a high incidence of symptomatic DVT following Achilles tendon rupture. The purpose of this study was to identify DVT risk factors inherent to Achilles tendon repair to determine which patients may benefit from prophylaxis. Methods One hundred and thirteen patient charts were reviewed following elective and nonelective Achilles tendon repair. For elective repair of insertional or noninsertional Achilles tendinopathy, parameters examined included lateral versus prone positioning and the presence versus absence of a flexor hallucis longus transfer. For nonelective repair, acute Achilles tendon ruptures were compared to chronic Achilles tendon ruptures. Results Of 113 Achilles tendon repairs, 3 venous thromboembolism (VTE) events (2.65%) occurred including 2 pulmonary emboli (1.77%). Seventeen of these repairs were chronic Achilles tendon ruptures, and all 3 VTE events (17.6%) occurred within this subgroup. Elevated body mass index was associated with VTE in patients with chronic Achilles ruptures although this did not reach significance (P = .064). No VTE events were reported after repair of 28 acute tendon ruptures or after 68 elective repairs of tendinopathy. Two patients with misdiagnosed partial Achilles tendon tears were excluded because they experienced a VTE event 3 weeks and 5 weeks after injury, prior to surgery. Conclusion In our retrospective review, chronic Achilles ruptures had a statistically significant higher incidence of VTE compared with acute Achilles ruptures (P = .048) or elective repair (P = .0069). Pharmaceutical anticoagulation may be considered for repair of chronic ruptures. Repair of acute ruptures and elective repair may not warrant routine prophylaxis due to a lower incidence of VTE.

  4. Enzyme kinetics of conjugating enzymes: PAPS sulfotransferase.

    Science.gov (United States)

    James, Margaret O

    2014-01-01

    The sulfotransferase (SULT) enzymes catalyze the formation of sulfate esters or sulfamates from substrates that contain hydroxy or amine groups, utilizing 3'-phosphoadenosyl-5'-phosphosulfate (PAPS) as the donor of the sulfonic group. The rate of product formation depends on the concentrations of PAPS and substrate as well as the sulfotransferase enzyme; thus, if PAPS is held constant while varying substrate concentration (or vice versa), the kinetic constants derived are apparent constants. When studied over a narrow range of substrate concentrations, classic Michaelis-Menten kinetics can be observed with many SULT enzymes and most substrates. Some SULT enzymes exhibit positive or negative cooperativity during conversion of substrate to product, and the kinetics fit the Hill plot. A characteristic feature of most sulfotransferase-catalyzed reactions is that, when studied over a wide range of substrate concentrations, the rate of product formation initially increases as substrate concentration increases, then decreases at high substrate concentrations, i.e., they exhibit substrate inhibition or partial substrate inhibition. This chapter gives an introduction to sulfotransferases, including a historical note, the nomenclature, a description of the function of SULTs with different types of substrates, presentation of examples of enzyme kinetics with SULTs, and a discussion of what is known about mechanisms of substrate inhibition in the sulfotransferases.

  5. How to repair an episiotomy.

    Science.gov (United States)

    Steen, Mary; Cummins, Bernie

    2016-02-17

    Rationale and key points Skilful repair of an episiotomy is an important aspect of maternal health care. It is essential that midwives and doctors have the knowledge and skills to undertake this procedure in a safe and effective manner. ▶ An episiotomy should be repaired promptly to reduce blood loss and prevent infection. ▶ Repair of an episiotomy is undertaken in three stages: repair of the vaginal mucosa, repair of the muscle layer and repair of the skin layer. ▶ Adequate pain relief should be provided before suturing. Reflective activity Clinical skills articles can help update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. Why a rectal examination is recommended before and following repair of an episiotomy. 2. What you would do to improve your suturing skills. 3. The factors that may prevent or delay an episiotomy from healing. Subscribers can upload their reflective accounts at rcni.com/portfolio .

  6. DNA repair in Chromobacterium violaceum.

    Science.gov (United States)

    Duarte, Fábio Teixeira; Carvalho, Fabíola Marques de; Bezerra e Silva, Uaska; Scortecci, Kátia Castanho; Blaha, Carlos Alfredo Galindo; Agnez-Lima, Lucymara Fassarella; Batistuzzo de Medeiros, Silvia Regina

    2004-03-31

    Chromobacterium violaceum is a Gram-negative beta-proteobacterium that inhabits a variety of ecosystems in tropical and subtropical regions, including the water and banks of the Negro River in the Brazilian Amazon. This bacterium has been the subject of extensive study over the last three decades, due to its biotechnological properties, including the characteristic violacein pigment, which has antimicrobial and anti-tumoral activities. C. violaceum promotes the solubilization of gold in a mercury-free process, and has been used in the synthesis of homopolyesters suitable for the production of biodegradable polymers. The complete genome sequence of this organism has been completed by the Brazilian National Genome Project Consortium. The aim of our group was to study the DNA repair genes in this organism, due to their importance in the maintenance of genomic integrity. We identified DNA repair genes involved in different pathways in C. violaceum through a similarity search against known sequences deposited in databases. The phylogenetic analyses were done using programs of the PHILYP package. This analysis revealed various metabolic pathways, including photoreactivation, base excision repair, nucleotide excision repair, mismatch repair, recombinational repair, and the SOS system. The similarity between the C. violaceum sequences and those of Neisserie miningitidis and Ralstonia solanacearum was greater than that between the C. violaceum and Escherichia coli sequences. The peculiarities found in the C. violaceum genome were the absence of LexA, some horizontal transfer events and a large number of repair genes involved with alkyl and oxidative DNA damage.

  7. DNA excision-repair defect of xeroderma pigmentosum prevents removal of a class of oxygen free radical-induced base lesions.

    Science.gov (United States)

    Satoh, M S; Jones, C J; Wood, R D; Lindahl, T

    1993-07-01

    Plasmid DNA was gamma-irradiated or treated with H2O2 in the presence of Cu2+ to generate oxygen free radical-induced lesions. Open circular DNA molecules were removed by ethidium bromide/CsCl density gradient centrifugation. The closed circular DNA fraction was treated with the Escherichia coli reagent enzymes endonuclease III (Nth protein) and Fpg protein. This treatment converted DNA molecules containing the major base lesions pyrimidine hydrates and 8-hydroxyguanine to a nicked form. Remaining closed circular DNA containing other oxygen radical-induced base lesions was used as a substrate for nucleotide excision-repair in a cell-free system. Extracts from normal human cells, but not extracts from xeroderma pigmentosum cells, catalyzed repair synthesis in this DNA. The repair defect in the latter extracts could be specifically corrected by in vitro complementation. The data suggest that accumulation of endogenous oxidative damage in cellular DNA from xeroderma pigmentosum patients contributes to the increased frequency of internal cancers and the neural degeneration occurring in serious cases of the syndrome.

  8. 40 CFR 798.5500 - Differential growth inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA...

    Science.gov (United States)

    2010-07-01

    ... repair proficient and repair deficient bacteria: âBacterial DNA damage or repair tests.â 798.5500 Section... inhibition of repair proficient and repair deficient bacteria: “Bacterial DNA damage or repair tests.” (a... killing or growth inhibition of repair deficient bacteria in a set of repair proficient and deficient...

  9. Bone repair and stem cells.

    Science.gov (United States)

    Ono, Noriaki; Kronenberg, Henry M

    2016-10-01

    Bones are an important component of vertebrates; they grow explosively in early life and maintain their strength throughout life. Bones also possess amazing capabilities to repair-the bone is like new without a scar after complete repair. In recent years, a substantial progress has been made in our understanding on mammalian bone stem cells. Mouse genetic models are powerful tools to understand the cell lineage, giving us better insights into stem cells that regulate bone growth, maintenance and repair. Recent findings about these stem cells raise new questions that require further investigations.

  10. Repairing and Upgrading Your PC

    CERN Document Server

    Thompson, Robert

    2009-01-01

    Repairing and Upgrading Your PC delivers start-to-finish instructions, simple enough for even the most inexperienced PC owner, for troubleshooting, repairing, and upgrading your computer. Written by hardware experts Robert Bruce Thompson and Barbara Fritchman Thompson, this book covers it all: how to troubleshoot a troublesome PC, how to identify which components make sense for an upgrade, and how to tear it all down and put it back together. This book shows how to repair and upgrade all of your PC's essential components.

  11. Laparoscopic repair of incisional hernia.

    Science.gov (United States)

    Lau, H; Lee, F; Patil, N G

    2001-09-01

    A 75-year-old man developed an incisional hernia over the upper abdomen following a wedge resection of a gastric stromal tumour in 1996. This is the first published report of a successful repair of an incisional hernia via a laparoscopic intraperitoneal on-lay technique using GORE-TEX DualMesh material in Hong Kong. Compared with conventional open repair of incisional hernia, long incisions and wound tension are avoided using the laparoscopic approach. This translates into a reduced risk of wound-related complications and facilitates recovery. In selected cases, minimally invasive surgery is a safe technique for the repair of incisional hernias.

  12. [Inguinal and femoral hernia repair].

    Science.gov (United States)

    Geissler, B; Anthuber, M

    2011-05-01

    With an incidence of 200,000 new cases per year in Germany, inguinal hernia has a significant socioeconomic impact. The 2009 guidelines from the European Hernia Society established treatment recommendations. Hernia repair is based on reinforcing the posterior wall of the inguinal canal by suture or mesh repair by an anterior or posterior approach. Lightweight mesh reduces recurrence rates and is the treatment of choice even in primary hernias. Laparoscopic hernia repair is associated with specific risks but is superior in postoperative pain and earlier return to work.

  13. Chronic Pain after Inguinal Hernia Repair.

    Science.gov (United States)

    Manangi, Mallikarjuna; Shivashankar, Santhosh; Vijayakumar, Abhishek

    2014-01-01

    Background. Chronic postherniorrhaphy groin pain is defined as pain lasting >6 months after surgery, which is one of the most important complications occurring after inguinal hernia repair, which occurs with greater frequency than previously thought. Material and Methods. Patients undergoing elective inguinal hernioplasty in Victoria Hospital from November 2011 to May 2013 were included in the study. A total of 227 patients met the inclusion criteria and were available for followup at end of six months. Detailed preoperative, intraoperative, and postoperative details of cases were recorded according to proforma. The postoperative pain and pain at days two and seven and at end of six months were recorded on a VAS scale. Results. Chronic pain at six-month followup was present in 89 patients constituting 39.4% of all patients undergoing hernia repair. It was seen that 26.9% without preoperative pain developed chronic pain whereas 76.7% of patients with preoperative pain developed chronic pain. Preemptive analgesia failed to show statistical significance in development of chronic pain (P = 0.079). Nerve injury was present in 22 of cases; it was found that nerve injury significantly affected development of chronic pain (P = 0.001). On multivariate analysis, it was found that development of chronic pain following hernia surgery was dependent upon factors like preoperative pain, type of anesthesia, nerve injury, postoperative local infiltration, postoperative complication, and most importantly the early postoperative pain. Conclusions. In the present study, we found that chronic pain following inguinal hernia repair causes significant morbidity to patients and should not be ignored. Preemptive analgesia and operation under local anesthesia significantly affect pain. Intraoperative identification and preservation of all inguinal nerves are very important. Early diagnosis and management of chronic pain can remove suffering of the patient.

  14. Double-strand break repair on sex chromosomes: challenges during male meiotic prophase

    OpenAIRE

    Lu, Lin-Yu; Yu, Xiaochun

    2015-01-01

    During meiotic prophase, DNA double-strand break (DSB) repair-mediated homologous recombination (HR) occurs for exchange of genetic information between homologous chromosomes. Unlike autosomes or female sex chromosomes, human male sex chromosomes X and Y share little homology. Although DSBs are generated throughout male sex chromosomes, homologous recombination does not occur for most regions and DSB repair process is significantly prolonged. As a result, male sex chromosomes are coated with ...

  15. Laparoscopic Inguinal Hernia Repair

    Science.gov (United States)

    ... hernia occurs when the inside layers of the abdominal muscle have weakened, resulting in a bulge or tear. ... is a technique to fix tears in the abdominal wall (muscle) using small incisions, telescopes and a patch (mesh). ...

  16. Enzymes for improved biomass conversion

    Science.gov (United States)

    Brunecky, Roman; Himmel, Michael E.

    2016-02-02

    Disclosed herein are enzymes and combinations of the enzymes useful for the hydrolysis of cellulose and the conversion of biomass. Methods of degrading cellulose and biomass using enzymes and cocktails of enzymes are also disclosed.

  17. Enzymes for improved biomass conversion

    Energy Technology Data Exchange (ETDEWEB)

    Brunecky, Roman; Himmel, Michael E.

    2016-02-02

    Disclosed herein are enzymes and combinations of the enzymes useful for the hydrolysis of cellulose and the conversion of biomass. Methods of degrading cellulose and biomass using enzymes and cocktails of enzymes are also disclosed.

  18. Large myelomeningocele repair

    Directory of Open Access Journals (Sweden)

    Farideh Nejat

    2011-01-01

    Full Text Available Background: Wound closure is accomplished in most cases of myelomeningocele (MMC by undermining of the skin edges surrounding the defect. However, large defects cannot be closed reliably by this simple technique. Due to the technical challenge associated with large MMC, surgeons have devised different methods for repairing large defects. In this paper, we report our experience of managing large defects, which we believe bears a direct relationship to decrease the incidence of wound complications. Materials and Methods: Forty children with large MMCs underwent surgical repair and represent our experience. We recommend using all hairy skin around the defect as a way to decrease the tension on the edges of the wound and the possible subsequent necrosis. It is our experience that vertical incision on one or two flanks parallel to the midline can decrease the tension of the wound. Moreover, ventriculo-peritoneal shunting for children who developed hydrocephalus was performed simultaneously, which constitutes another recommendation for preventing fluid collection and build up of pressure on the wound. Results: Patients in this study were in the age range of 2 days to 8 years. The most common location of MMC was in the thoracolumbar area. All but four patients had severe weakness in lower extremities. We used as much hairy skin around the MMC sac as possible in all cases. Vertical incisions on one or both flanks and simultaneous shunt procedure were performed in 36 patients. We treated children with large MMC defects with acceptable tension-free closure. Nonetheless, three patients developed superficial skin infection and partial wound dehiscence, and they were managed conservatively. Conclusions: We recommend using all hairy skin around the MMC defect for closure of large defects. In cases that were expected to be at a higher risk to develop dehiscence release incisions on one or two flanks towards the fascia were found to be useful. Simultaneous

  19. Enzymes involved in triglyceride hydrolysis.

    Science.gov (United States)

    Taskinen, M R; Kuusi, T

    1987-08-01

    The lipolytic enzymes LPL and HL play important roles in the metabolism of lipoproteins and participate in lipoprotein interconversions. LPL was originally recognized to be the key enzyme in the hydrolysis of chylomicrons and triglyceride, but it also turned out to be one determinant of HDL concentration in plasma. When LPL activity is high, chylomicrons and VLDL are rapidly removed from circulation and a concomitant rise of the HDL2 occurs. In contrast, low LPL activity impedes the removal of triglyceride-rich particles, resulting in the elevation of serum triglycerides and a decrease of HDL (HDL2). Concordant changes of this kind in LPL and HDL2 are induced by many physiological and pathological perturbations. Finally, the operation of LPL is also essential for the conversion of VLDL to LDL. This apparently clear-cut role of LPL in lipoprotein interconversions is contrasted with the enigmatic actions of HL. The enzyme was originally thought to participate in the catalyses of chylomicron and VLDL remnants generated in the LPL reaction. However, substantial in vitro and in vivo data indicate that HL is a key enzyme in the degradation of plasma HDL (HDL2) in a manner which opposes LPL. A scheme is presented for the complementary actions of the two enzymes in plasma HDL metabolism. In addition, recent studies have attributed a role to HL in the catabolism of triglyceride-rich lipoproteins, particularly those containing apo E. However, this function becomes clinically important only under conditions where the capacity of the LPL-mediated removal system is exceeded. Such a situation may arise when the input of triglyceride-rich particles (chylomicrons and/or VLDL) is excessive or LPL activity is decreased or absent.

  20. Profiling the orphan enzymes

    Science.gov (United States)

    2014-01-01

    The emergence of Next Generation Sequencing generates an incredible amount of sequence and great potential for new enzyme discovery. Despite this huge amount of data and the profusion of bioinformatic methods for function prediction, a large part of known enzyme activities is still lacking an associated protein sequence. These particular activities are called “orphan enzymes”. The present review proposes an update of previous surveys on orphan enzymes by mining the current content of public databases. While the percentage of orphan enzyme activities has decreased from 38% to 22% in ten years, there are still more than 1,000 orphans among the 5,000 entries of the Enzyme Commission (EC) classification. Taking into account all the reactions present in metabolic databases, this proportion dramatically increases to reach nearly 50% of orphans and many of them are not associated to a known pathway. We extended our survey to “local orphan enzymes” that are activities which have no representative sequence in a given clade, but have at least one in organisms belonging to other clades. We observe an important bias in Archaea and find that in general more than 30% of the EC activities have incomplete sequence information in at least one superkingdom. To estimate if candidate proteins for local orphans could be retrieved by homology search, we applied a simple strategy based on the PRIAM software and noticed that candidates may be proposed for an important fraction of local orphan enzymes. Finally, by studying relation between protein domains and catalyzed activities, it appears that newly discovered enzymes are mostly associated with already known enzyme domains. Thus, the exploration of the promiscuity and the multifunctional aspect of known enzyme families may solve part of the orphan enzyme issue. We conclude this review with a presentation of recent initiatives in finding proteins for orphan enzymes and in extending the enzyme world by the discovery of new

  1. Unhairing with enzymes

    OpenAIRE

    Crispim, A.; Mota, M.

    2003-01-01

    The use of enzymes in the leather industry is increasing and their application is being widened to include operations such as de-greasing, unhairing and other wet-end operations. Enzymes can also be used to assist with recycling leather wastes as well as to avoid pollution. The present work is devoted to illustrate the potential application of enzymes in unhairing without hair destruction. Enzymatic unhairing is based upon the weakening of the epidermis basal layer to which the hair is at...

  2. Common cellular events occur during wound healing and organ regeneration in the sea cucumber Holothuria glaberrima

    Directory of Open Access Journals (Sweden)

    García-Arrarás José E

    2007-10-01

    Full Text Available Abstract Background All animals possess some type of tissue repair mechanism. In some species, the capacity to repair tissues is limited to the healing of wounds. Other species, such as echinoderms, posses a striking repair capability that can include the replacement of entire organs. It has been reported that some mechanisms, namely extracellular matrix remodeling, appear to occur in most repair processes. However, it remains unclear to what extent the process of organ regeneration, particularly in animals where loss and regeneration of complex structures is a programmed natural event, is similar to wound healing. We have now used the sea cucumber Holothuria glaberrima to address this question. Results Animals were lesioned by making a 3–5 mm transverse incision between one of the longitudinal muscle pairs along the bodywall. Lesioned tissues included muscle, nerve, water canal and dermis. Animals were allowed to heal for up to four weeks (2, 6, 12, 20, and 28 days post-injury before sacrificed. Tissues were sectioned in a cryostat and changes in cellular and tissue elements during repair were evaluated using classical dyes, immmuohistochemistry and phalloidin labeling. In addition, the temporal and spatial distribution of cell proliferation in the animals was assayed using BrdU incorporation. We found that cellular events associated with wound healing in H. glaberrima correspond to those previously shown to occur during intestinal regeneration. These include: (1 an increase in the number of spherule-containing cells, (2 remodeling of the extracellular matrix, (3 formation of spindle-like structures that signal dedifferentiation of muscle cells in the area flanking the lesion site and (4 intense cellular division occurring mainly in the coelomic epithelium after the first week of regeneration. Conclusion Our data indicate that H. glaberrima employs analogous cellular mechanisms during wound healing and organ regeneration. Thus, it is possible

  3. Adenylate-forming enzymes

    Science.gov (United States)

    Schmelz, Stefan; Naismith, James H.

    2012-01-01

    Thioesters, amides and esters are common chemical building blocks in a wide array of natural products. The formation of these bonds can be catalyzed in a variety of ways. For chemists, the use of an activating group is a common strategy and adenylate enzymes are exemplars of this approach. Adenylating enzymes activate the otherwise unreactive carboxylic acid by transforming the normal hydroxyl leaving group into adenosine monophosphate. Recently there have been a number of studies of such enzymes and in this review we suggest a new classification scheme. The review highlights the diversity in enzyme fold, active site architecture and metal coordination that has evolved to catalyze this particular reaction. PMID:19836944

  4. Food and feed enzymes.

    Science.gov (United States)

    Fraatz, Marco Alexander; Rühl, Martin; Zorn, Holger

    2014-01-01

    Humans have benefited from the unique catalytic properties of enzymes, in particular for food production, for thousands of years. Prominent examples include the production of fermented alcoholic beverages, such as beer and wine, as well as bakery and dairy products. The chapter reviews the historic background of the development of modern enzyme technology and provides an overview of the industrial food and feed enzymes currently available on the world market. The chapter highlights enzyme applications for the improvement of resource efficiency, the biopreservation of food, and the treatment of food intolerances. Further topics address the improvement of food safety and food quality.

  5. Microbial amylolytic enzymes.

    Science.gov (United States)

    Vihinen, M; Mäntsälä, P

    1989-01-01

    Starch-degrading, amylolytic enzymes are widely distributed among microbes. Several activities are required to hydrolyze starch to its glucose units. These enzymes include alpha-amylase, beta-amylase, glucoamylase, alpha-glucosidase, pullulan-degrading enzymes, exoacting enzymes yielding alpha-type endproducts, and cyclodextrin glycosyltransferase. Properties of these enzymes vary and are somewhat linked to the environmental circumstances of the producing organisms. Features of the enzymes, their action patterns, physicochemical properties, occurrence, genetics, and results obtained from cloning of the genes are described. Among all the amylolytic enzymes, the genetics of alpha-amylase in Bacillus subtilis are best known. Alpha-Amylase production in B. subtilis is regulated by several genetic elements, many of which have synergistic effects. Genes encoding enzymes from all the amylolytic enzyme groups dealt with here have been cloned, and the sequences have been found to contain some highly conserved regions thought to be essential for their action and/or structure. Glucoamylase appears usually in several forms, which seem to be the results of a variety of mechanisms, including heterogeneous glycosylation, limited proteolysis, multiple modes of mRNA splicing, and the presence of several structural genes.

  6. A Two-Unit Cold Standby Repairable System with One Replaceable Repair Facility and Delay Repair:Some Reliability Problems

    Institute of Scientific and Technical Information of China (English)

    WEI Ying-yuan; TANG Ying-hui

    2004-01-01

    This paper considers a two-unit same cold standby repairable system with a replaceable repair facility and delay repair .The failure time of unit is assumed to follow exponential distribution , and the repair time and delay time of failed unit are assumed to follow arbitrary distributions , whereas the failure and replacement time distributions of the repair facility are exponential and arbitrary . By using the Markov renewal process theory, some primary reliability quantities of the system are obtained.

  7. 40 CFR 63.1024 - Leak repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Leak repair. 63.1024 Section 63.1024... Standards for Equipment Leaks-Control Level 2 Standards § 63.1024 Leak repair. (a) Leak repair schedule. The owner or operator shall repair each leak detected as soon as practical, but not later than 15...

  8. 40 CFR 65.105 - Leak repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Leak repair. 65.105 Section 65.105... FEDERAL AIR RULE Equipment Leaks § 65.105 Leak repair. (a) Leak repair schedule. The owner or operator shall repair each leak detected as soon as practical but not later than 15 calendar days after it...

  9. 40 CFR 63.1005 - Leak repair.

    Science.gov (United States)

    2010-07-01

    ... successful repair of the leak. (3) Maximum instrument reading measured by Method 21 of 40 CFR part 60... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Leak repair. 63.1005 Section 63.1005... Standards for Equipment Leaks-Control Level 1 § 63.1005 Leak repair. (a) Leak repair schedule. The owner...

  10. Post-production modification of industrial enzymes.

    Science.gov (United States)

    Minten, Inge J; Abello, Nicolas; Schooneveld-Bergmans, Margot E F; van den Berg, Marco A

    2014-01-01

    Industry has an increasing interest in the use of enzymes as environmentally friendly, highly efficient, and specific bio-catalysts. Enzymes have primarily evolved to function in aqueous environments at ambient temperature and pressure. These conditions however do not always correspond with industrial processes or applications, and only a small portion of all known enzymes are therefore suitable for industrial use. Protein engineering can sometimes be applied to convey more desirable properties to enzymes, such as increased stability, but is limited to the 20 naturally occurring amino acids or homologs thereof. Using post-production modification, which has the potential to combine desirable properties from the enzyme and the conjugated compounds, enzymes can be modified with both natural and synthetic molecules. This offers access to a myriad of possibilities for tuning the properties of enzymes. At this moment, however, the effects of post-production modification cannot yet be reliably predicted. The increasing number of applications will improve this so that the potential of this technology can be fully exploited. This review will focus on post-production modification of enzymes and its use and opportunities in industry.

  11. DNA repair deficiency in neurodegeneration

    DEFF Research Database (Denmark)

    Jeppesen, Dennis Kjølhede; Bohr, Vilhelm A; Stevnsner, Tinna V.

    2011-01-01

    : homologous recombination and non-homologous end-joining. Ataxia telangiectasia and related disorders with defects in these pathways illustrate that such defects can lead to early childhood neurodegeneration. Aging is a risk factor for neurodegeneration and accumulation of oxidative mitochondrial DNA damage......Deficiency in repair of nuclear and mitochondrial DNA damage has been linked to several neurodegenerative disorders. Many recent experimental results indicate that the post-mitotic neurons are particularly prone to accumulation of unrepaired DNA lesions potentially leading to progressive...... neurodegeneration. Nucleotide excision repair is the cellular pathway responsible for removing helix-distorting DNA damage and deficiency in such repair is found in a number of diseases with neurodegenerative phenotypes, including Xeroderma Pigmentosum and Cockayne syndrome. The main pathway for repairing oxidative...

  12. Early days of DNA repair: discovery of nucleotide excision repair and homology-dependent recombinational repair.

    Science.gov (United States)

    Rupp, W Dean

    2013-12-13

    The discovery of nucleotide excision repair in 1964 showed that DNA could be repaired by a mechanism that removed the damaged section of a strand and replaced it accurately by using the remaining intact strand as the template. This result showed that DNA could be actively metabolized in a process that had no precedent. In 1968, experiments describing postreplication repair, a process dependent on homologous recombination, were reported. The authors of these papers were either at Yale University or had prior Yale connections. Here we recount some of the events leading to these discoveries and consider the impact on further research at Yale and elsewhere.

  13. Construction, repair and maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Hinger, R. [Terasen Pipelines, Calgary, AB (Canada); Wong, P. [KC Integrity Corp., Calgary, AB (Canada); Yeomans, M.; Glover, A. [TransCanada PipeLines Ltd., Calgary, AB (Canada)

    2003-07-01

    The presentations by Working Group 4 focused on construction, repair and maintenance of pipelines with particular reference to high-strength steels and their applications for natural gas transmission pipelines. Discussions focused on how technology can be used to provide cost-effective design and construction solutions for long distance pipelines in a manner that does not compromise safety and reliability. The role that carbon plays in increasing the toughness of steel was also discussed. A few fundamental changes in steel production technology and a reduction in carbon content can result in a simultaneous increase in strength and toughness of steels. The cost impact of this technology was summarized. It was concluded that high strength steels offer effective solutions to deliver cost-effective pipelines to transport natural gas from northern basins. This session also presented pipeline routes that transport diluted bitumens from the Athabasca Oil Sands Project and the Muskeg River Mine to upgrader facilities in Alberta. Construction issues included design conservatism, water course crossings, winter construction, winter ditching, and public consultation. Examples of high strength steel pipe applications were also included with reference to experience gained by TransCanada and Corridor Pipeline. tabs., figs.

  14. Laparoscopic repair of postoperative perineal hernia.

    LENUS (Irish Health Repository)

    Ryan, Stephen

    2010-01-01

    Perineal hernias are infrequent complications following abdominoperineal operations. Various approaches have been described for repair of perineal hernias including open transabdominal, transperineal or combined abdominoperineal repairs. The use of laparoscopic transabdominal repair of perineal hernias is not well-described. We present a case report demonstrating the benefits of laparoscopic repair of perineal hernia following previous laparoscopic abdominoperineal resection (APR) using a nonabsorbable mesh to repair the defect. We have demonstrated that the use of laparoscopy with repair of the pelvic floor defect using a non absorbable synthetic mesh offers an excellent alternative with many potential advantages over open transabdominal and transperineal repairs.

  15. Natural transformation of Campylobacter jejuni occurs beyond limits of growth.

    Directory of Open Access Journals (Sweden)

    Christina S Vegge

    Full Text Available Campylobacter jejuni is a human bacterial pathogen. While poultry is considered to be a major source of food borne campylobacteriosis, C. jejuni is frequently found in the external environment, and water is another well-known source of human infections. Natural transformation is considered to be one of the main mechanisms for mediating transfer of genetic material and evolution of the organism. Given the diverse habitats of C. jejuni we set out to examine how environmental conditions and physiological processes affect natural transformation of C. jejuni. We show that the efficiency of transformation is correlated to the growth conditions, but more importantly that transformation occurs at growth-restrictive conditions as well as in the late stationary phase; hence revealing that growth per se is not required for C. jejuni to be competent. Yet, natural transformation of C. jejuni is an energy dependent process, that occurs in the absence of transcription but requires an active translational machinery. Moreover, we show the ATP dependent ClpP protease to be important for transformation, which possibly could be associated with reduced protein glycosylation in the ClpP mutant. In contrast, competence of C. jejuni was neither found to be involved in DNA repair following DNA damage nor to provide a growth benefit. Kinetic studies revealed that several transformation events occur per cell cycle indicating that natural transformation of C. jejuni is a highly efficient process. Thus, our findings suggest that horizontal gene transfer by natural transformation takes place in various habitats occupied by C. jejuni.

  16. Umbilical and epigastric hernia repair.

    Science.gov (United States)

    Muschaweck, Ulrike

    2003-10-01

    The repair of umbilical and epigastric hernias still represents a challenge to surgeons. Although a common and relatively simple procedure, there is no exact protocol today on how the repair should be done. The Mayo technique and its alterations could not stand the test of time: a recurrence rate of 20% and higher is not acceptable for any surgical procedure. Although there is no consensus opinion, one thing is clear: the importance of an anatomic repair without tension and without an artificial enlargement of the defect. In 1987 Lichtenstein reported on 6321 cases of herniorraphy with a tension free repair, and in 1994 Stuart reemphasized that special importance in his editorial in the Lancet. A newer study from Brancato and coworkers in Italy also states the advantage of a tension-free prosthetic repair in 16 patients with epigastric hernia. We have gone even further and recommend a tailored-to-the-patient repair using a customized polypropylene mesh and a one-layer running suture. The advantages should be obvious: no artificial creation of an even bigger than original defect, a completely tension-free repair, and little to no recurrence of the hernia. Our results clearly prove that assumption. Moreover, the procedure is extremely safe and complications are very rare and minor. We conclude that using a mesh plug in a customized tension-free repair of umbilical and epigastric hernia shows many advantages over the commonly used methods. And we finally conclude with the words of Albert Einstein: "The only source of knowledge is experience."

  17. Repair Types, Procedures - Part 1

    Science.gov (United States)

    2010-05-01

    New Jersey, USA. Repair Types, Procedures – Part I RTO-EN-AVT-156 9 - 19 [5] Drieker R, Botello C, MacBeth S, and Grody J, “Aircraft Battle... MacBeth S, and Grody J, “Aircraft Battle Damage Assessment and Repair (ABDAR), Vol. III: Field Test Report,” AFRL-HE-WP-TR-2002-0039, July 2000. [8

  18. Hand function after nerve repair.

    OpenAIRE

    Lundborg, Göran; Rosén, Birgitta

    2007-01-01

    Treatment of injuries to major nerve trunks in the hand and upper extremity remains a major and challenging reconstructive problem. Such injuries may cause long-lasting disabilities in terms of lost fine sensory and motor functions. Nowadays there is no surgical repair technique that can ensure recovery of tactile discrimination in the hand of an adult patient following nerve repair while very young individuals usually regain a complete recovery of functional sensibility. Post-traumatic nerve...

  19. Cobbler's technique for Iridodialysis repair

    Directory of Open Access Journals (Sweden)

    Surinder Singh Pandav

    2016-01-01

    Full Text Available We describe a novel “Cobbler's technique” for iridodialysis repair in the right eye of a patient aged 18 years, with a traumatic iridodialysis secondary to open globe injury with an iron rod. Our technique is simple with easy surgical maneuvers, that is, effective for repairing iridodialysis. The “Cobbler's technique” allows a maximally functional and cosmetic result for iridodialysis.

  20. Rehabilitation after Rotator Cuff Repair.

    Science.gov (United States)

    Nikolaidou, Ourania; Migkou, Stefania; Karampalis, Christos

    2017-01-01

    Rotator cuff tears are a very common condition that is often incapacitating. Whether non-surgical or surgical, successful management of rotator cuff disease is dependent on appropriate rehabilitation. If conservative management is insufficient, surgical repair is often indicated. Postsurgical outcomes for patients having had rotator cuff repair can be quite good. A successful outcome is much dependent on surgical technique as it is on rehabilitation. Numerous rehabilitation protocols for the management of rotator cuff disease are based primarily on clinical experience and expert opinion. This article describes the different rehabilitation protocols that aim to protect the repair in the immediate postoperative period, minimize postoperative stiffness and muscle atrophy. A review of currently available literature on rehabilitation after arthroscopic rotator cuff tear repair was performed to illustrate the available evidence behind various postoperative treatment modalities. There were no statistically significant differences between a conservative and an accelerated rehabilitation protocol . Early passive range of motion (ROM) following arthroscopic cuff repair is thought to decrease postoperative stiffness and improve functionality. However, early aggressive rehabilitation may compromise repair integrity. The currently available literature did not identify any significant differences in functional outcomes and relative risks of re-tears between delayed and early motion in patients undergoing arthroscopic rotator cuff repairs. A gentle rehabilitation protocol with limits in range of motion and exercise times after arthroscopic rotator cuff repair would be better for tendon healing without taking any substantial risks. A close communication between the surgeon, the patient and the physical therapy team is important and should continue throughout the whole recovery process.

  1. Repairing Learned Knowledge Using Experience

    Science.gov (United States)

    1990-05-01

    It necessar and Identify by’ 6109h nii be) learning precedent-based learning knowledge repair explanation-based learning near - miss groups 20. ABSTRACT...can a program use explanations to repair a recollection, preventing further misapplication? Near - Miss Groups Isolate Suspicious Relations If a metal...pail differs from a porcelain cup only in the position of handle attachment, then we would say that the pail is a near miss . Unfortunately, there are

  2. Aircraft Metal Skin Repair and Honeycomb Structure Repair; Sheet Metal Work 3: 9857.02.

    Science.gov (United States)

    Dade County Public Schools, Miami, FL.

    The course helps students determine types of repairs, compute repair sizes, and complete the repair through surface protection. Course content includes goals, specific objectives, protection of metals, repairs to metal skin, and honeycomb structure repair. A bibliography and post-test are appended. A prerequisite for this course is mastery of the…

  3. Allergies and Asthma: They Often Occur Together

    Science.gov (United States)

    ... you miserable. A lot, as it turns out. Allergies and asthma often occur together. The same substances that trigger your hay fever symptoms, such as pollen, dust mites and pet dander, may also cause asthma signs ...

  4. Multiple Primary Cancers: Simultaneously Occurring Prostate ...

    African Journals Online (AJOL)

    2016-05-20

    May 20, 2016 ... occurring prostate cancer and other primary tumors-our experience and literature ... carcinoma, primary liver cell carcinoma, and thyroid follicular carcinoma in both ..... malignancies in women with papillary thyroid cancer.

  5. ST elevation occurring during stress testing

    Directory of Open Access Journals (Sweden)

    Diana Malouf

    2016-04-01

    Full Text Available A case is presented of significant reversible ST elevation occurring during treadmill testing, and the coronary anatomy and subsequent course are described, indicating that ischemia is a potential cause of this electrocardiographic finding.

  6. Trichotillomania and Co-occurring Anxiety

    Science.gov (United States)

    Grant, Jon E.; Redden, Sarah A.; Leppink, Eric W.; Chamberlain, Samuel R.

    2017-01-01

    Background Trichotillomania appears to be a fairly common disorder, with high rates of co-occurring anxiety disorders. Many individuals with trichotillomania also report that pulling worsens during periods of increased anxiety. Even with these clinical links to anxiety, little research has explored whether trichotillomania with co-occurring anxiety is a meaningful subtype. Methods 165 adults with trichotillomania were examined on a variety of clinical measures including symptom severity, functioning, and comorbidity. Participants also underwent cognitive testing assessing motor inhibition and cognitive flexibility. Clinical features and cognitive functioning were compared between those with current co-occurring anxiety disorders (i.e. social anxiety, generalized anxiety disorder, panic disorder, and anxiety disorder NOS) (n=38) and those with no anxiety disorder (n=127). Results Participants with trichotillomania and co-occurring anxiety reported significantly worse hair pulling symptoms, were more likely to have co-occurring depression, and were more likely to have a first-degree relative with obsessive compulsive disorder. Those with anxiety disorders also exhibited significantly worse motor inhibitory performance on a task of motor inhibition (stop-signal task). Conclusions This study suggests that anxiety disorders affect the clinical presentation of hair pulling behavior. Further research is needed to validate our findings and to consider whether treatments should be specially tailored differently for adults with trichotillomania who have co-occurring anxiety disorders, or more pronounced cognitive impairment. PMID:27668531

  7. Base excision repair in sugarcane

    Directory of Open Access Journals (Sweden)

    Agnez-Lima Lucymara F.

    2001-01-01

    Full Text Available DNA damage can be induced by a large number of physical and chemical agents from the environment as well as compounds produced by cellular metabolism. This type of damage can interfere with cellular processes such as replication and transcription, resulting in cell death and/or mutations. The low frequency of mutagenesis in cells is due to the presence of enzymatic pathways which repair damaged DNA. Several DNA repair genes (mainly from bacteria, yeasts and mammals have been cloned and their products characterized. The high conservation, especially in eukaryotes, of the majority of genes related to DNA repair argues for their importance in the maintenance of life on earth. In plants, our understanding of DNA repair pathways is still very poor, the first plant repair genes having only been cloned in 1997 and the mechanisms of their products have not yet been characterized. The objective of our data mining work was to identify genes related to the base excision repair (BER pathway, which are present in the database of the Sugarcane Expressed Sequence Tag (SUCEST Project. This search was performed by tblastn program. We identified sugarcane clusters homologous to the majority of BER proteins used in the analysis and a high degree of conservation was observed. The best results were obtained with BER proteins from Arabidopsis thaliana. For some sugarcane BER genes, the presence of more than one form of mRNA is possible, as shown by the occurrence of more than one homologous EST cluster.

  8. Scarf Repair of Composite Laminates

    Directory of Open Access Journals (Sweden)

    Xie Zonghong

    2016-01-01

    Full Text Available The use of composite materials, such as carbon-fiber reinforced plastic (CFRP composites, aero-structures has led to an increased need of advanced assembly joining and repair technologies. Adhesive bonded repairs as an alternative to recover full or part of initial strength were investigated. Tests were conducted with the objective of evaluating the effectiveness of techniques used for repairing damage fiber reinforced laminated composites. Failure loads and failure modes were generated and compared with the following parameters: scarf angles, roughness of grind tool and number of external plies. Results showed that scarf angle was the critical parameter and the largest tensile strength was observed with the smallest scarf angle. Besides, the use of external plies at the outer surface could not increase the repairs efficiency for large scarf angle. Preparing the repair surfaces by sanding them with a sander ranging from 60 to 100 grit number had significant effect on the failure load. These results allowed the proposal of design principles for repairing CFRP structures.

  9. Aging and DNA repair capability. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Tice, R R

    1977-01-01

    A review of the literature on DNA repair processes in relation to aging is presented under the following headings: DNA repair processes; age-related occurrence of unrepaired DNA lesions; DNA repair capability as a function of age; tissue-specific DNA repair capability; acceleration of the aging process by exposure to DNA damaging agents; human genetic syndromes; and longevity and DNA repair processes. (HLW)

  10. Novel Inhibitors of Rad6 Ubiquitin Conjugating Enzyme: Design, Synthesis, Identification, and Functional Characterization

    Science.gov (United States)

    Nangia-Makker, Pratima; Balan, Vitaly; Morelli, Matteo; Kothayer, Hend; Westwell, Andrew D.; Shekhar, Malathy P.V.

    2013-01-01

    Protein ubiquitination is important for cell signaling, DNA repair, and proteasomal degradation, and it is not surprising that alterations in ubiquitination occur frequently in cancer. Ubiquitin-conjugating enzymes (E2) mediate ubiquitination by selective interactions with ubiquitin-activating (E1) and ubiquitin ligase (E3) enzymes, and thus selective E2 small molecule inhibitor (SMI) will provide specificity unattainable with proteasome inhibitors. Here we describe synthesis and functional characterization of the first SMIs of human E2 Rad6B, a fundamental component of translesion synthesis DNA repair. A pharmacophore model for consensus E2 ubiquitin-binding sites was generated for virtual screening to identify E2 inhibitor candidates. Twelve triazine (TZ) analogs screened in silico by molecular docking to the Rad6B X-ray structure were verified by their effect on Rad6B ubiquitination of histone H2A. TZs #8 and 9 docked to the Rad6B catalytic site with highest complementarity. TZs #1, 2, 8, and 9 inhibited Rad6B-ubiquitin thioester formation and subsequent ubiquitin transfer to histone H2A. SMI #9 inhibition of Rad6 was selective as BCA2 ubiquitination by E2 UbcH5 was unaffected by SMI #9. SMI #9 more potently inhibited proliferation, colony formation, and migration than SMI #8, and induced MDA-MB-231 breast cancer cell G2–M arrest and apoptosis. Ubiquitination assays using Rad6 immunoprecipitated from SMI #8- or 9-treated cells confirmed inhibition of endogenous Rad6 activity. Consistent with our previous data showing Rad6B-mediated polyubiquitination stabilizes β-catenin, MDAMB-231 treatment with SMIs #8 or 9 decreased β-catenin protein levels. Together these results describe identification of the first Rad6 SMIs. PMID:23339190

  11. Repair of the Peripheral Nerve—Remyelination that Works

    DEFF Research Database (Denmark)

    Fex Svenningsen, Åsa; Dahlin, Lars

    2013-01-01

    Abstract: In this review we summarize the events known to occur after an injury in the peripheral nervous system. We have focused on the Schwann cells, as they are the most important cells for the repair process and facilitate axonal outgrowth. The environment created by this cell type is essential...... for the outcome of the repair process. The review starts with a description of the current state of knowledge about the initial events after injury, followed by Wallerian degeneration, and subsequent regeneration. The importance of surgical repair, carried out as soon as possible to increase the chances of a good...... outcome, is emphasized throughout the review. The review concludes by describing the target re-innervation, which today is one of the most serious problems for nerve regeneration. It is clear, compiling this data, that even though regeneration of the peripheral nervous system is possible, more research...

  12. Pregnancy after fontan repair of complex congenital heart disease.

    Science.gov (United States)

    Hoare, J V; Radford, D

    2001-11-01

    We describe four successful pregnancies in three women who had previously had a Fontan repair for congenital heart disease. Each pregnancy resulted in a live birth and there was no maternal mortality The infants were premature, being delivered at 26, 30 and 35 weeks, and weighing 1,020, 1,333 and 1,930 g respectively The fourth infant was born at 32 weeks and no birthweight is available. Maternal complications occurred and were those anticipated after a Fontan repair. Two mothers required treatment for supraventricular arrhythmias (atrial flutter and fibrillation). Ventricular failure was present in two mothers and required ongoing drug treatment. Raised systemic venous pressures caused peripheral oedema in two mothers and hepatomegaly and ascites in one mother. The physiology, potential complications, anaesthetic concerns and drug treatment in pregnancy after Fontan repair are discussed.

  13. DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair

    Directory of Open Access Journals (Sweden)

    Elisa Mentegari

    2016-08-01

    Full Text Available DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell’s genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy.

  14. An approach to estimate radioadaptation from DSB repair efficiency.

    Science.gov (United States)

    Yatagai, Fumio; Sugasawa, Kaoru; Enomoto, Shuichi; Honma, Masamitsu

    2009-09-01

    In this review, we would like to introduce a unique approach for the estimation of radioadaptation. Recently, we proposed a new methodology for evaluating the repair efficiency of DNA double-strand breaks (DSB) using a model system. The model system can trace the fate of a single DSB, which is introduced within intron 4 of the TK gene on chromosome 17 in human lymphoblastoid TK6 cells by the expression of restriction enzyme I-SceI. This methodology was first applied to examine whether repair of the DSB (at the I-SceI site) can be influenced by low-dose, low-dose rate gamma-ray irradiation. We found that such low-dose IR exposure could enhance the activity of DSB repair through homologous recombination (HR). HR activity was also enhanced due to the pre-IR irradiation under the established conditions for radioadaptation (50 mGy X-ray-6 h-I-SceI treatment). Therefore, radioadaptation might account for the reduced frequency of homozygous loss of heterozygosity (LOH) events observed in our previous experiment (50 mGy X-ray-6 h-2 Gy X-ray). We suggest that the present evaluation of DSB repair using this I-SceI system, may contribute to our overall understanding of radioadaptation.

  15. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  16. Artificial Enzymes, "Chemzymes"

    DEFF Research Database (Denmark)

    Bjerre, Jeannette; Rousseau, Cyril Andre Raphaël; Pedersen, Lavinia Georgeta M

    2008-01-01

    Enzymes have fascinated scientists since their discovery and, over some decades, one aim in organic chemistry has been the creation of molecules that mimic the active sites of enzymes and promote catalysis. Nevertheless, even today, there are relatively few examples of enzyme models that successf......Enzymes have fascinated scientists since their discovery and, over some decades, one aim in organic chemistry has been the creation of molecules that mimic the active sites of enzymes and promote catalysis. Nevertheless, even today, there are relatively few examples of enzyme models...... that successfully perform Michaelis-Menten catalysis under enzymatic conditions (i.e., aqueous medium, neutral pH, ambient temperature) and for those that do, very high rate accelerations are seldomly seen. This review will provide a brief summary of the recent developments in artificial enzymes, so called...... "Chemzymes", based on cyclodextrins and other molecules. Only the chemzymes that have shown enzyme-like activity that has been quantified by different methods will be mentioned. This review will summarize the work done in the field of artificial glycosidases, oxidases, epoxidases, and esterases, as well...

  17. The new base excision repair pathway in mammals mediated by tyrosyl-DNA-phosphodiesterase 1

    Directory of Open Access Journals (Sweden)

    Lavrik O. I.

    2012-06-01

    Full Text Available Human tyrosyl-DNA phosphodiesterase 1 (Tdp1 hydrolyzes the phosphodiester bond at a DNA 3' end linked to a tyrosyl moiety and has been implicated in the repair of Topoisomerase I (TopI-DNA covalent complexes. Tdp1 can also hydrolyze other 3' end DNA alterations including 3' phosphoglycolate and 3' abasic (AP sites, and exhibits the 3' nucleosidase activity indicating that it may function as a general 3' end-processing DNA repair enzyme. Recently we have shown a new Tdp1 activity generating DNA strand break with the 3' phosphate termini from the AP site. AP sites are formed spontaneously and are inevitable intermediates during base excision repair of DNA base damages. AP sites are both mutagenic and cytotoxic, and key enzymes for their removal are AP endonucleases. However, AP endonuclease independent repair, initiated by DNA glycosylases performing beta, delta-elimination cleavage of the AP sites, has been described in mammalian cells. Here, we describe another AP endonuclease independent repair pathway for removal of AP sites that is initiated by tyrosyl phosphodiesterase Tdp1. We propose that repair is completed by the action of a polynucleotide kinase, a DNA polymerase and finally a DNA ligase to seal the gap.

  18. Mutagenic roles of DNA "repair" proteins in antibody diversity and disease-associated trinucleotide repeat instability.

    Science.gov (United States)

    Slean, Meghan M; Panigrahi, Gagan B; Ranum, Laura P; Pearson, Christopher E

    2008-07-01

    While DNA repair proteins are generally thought to maintain the integrity of the whole genome by correctly repairing mutagenic DNA intermediates, there are cases where DNA "repair" proteins are involved in causing mutations instead. For instance, somatic hypermutation (SHM) and class switch recombination (CSR) require the contribution of various DNA repair proteins, including UNG, MSH2 and MSH6 to mutate certain regions of immunoglobulin genes in order to generate antibodies of increased antigen affinity and altered effector functions. Another instance where "repair" proteins drive mutations is the instability of gene-specific trinucleotide repeats (TNR), the causative mutations of numerous diseases including Fragile X mental retardation syndrome (FRAXA), Huntington's disease (HD), myotonic dystrophy (DM1) and several spinocerebellar ataxias (SCAs) all of which arise via various modes of pathogenesis. These healthy and deleterious mutations that are induced by repair proteins are distinct from the genome-wide mutations that arise in the absence of repair proteins: they occur at specific loci, are sensitive to cis-elements (sequence context and/or epigenetic marks) and transcription, occur in specific tissues during distinct developmental windows, and are age-dependent. Here we review and compare the mutagenic role of DNA "repair" proteins in the processes of SHM, CSR and TNR instability.

  19. Holliday junction processing enzymes as guardians of genome stability.

    Science.gov (United States)

    Sarbajna, Shriparna; West, Stephen C

    2014-09-01

    Holliday junctions (HJs) are four-stranded DNA intermediates that arise during the recombinational repair of DNA double-strand breaks (DSBs). Their timely removal is crucial for faithful chromosome segregation and genome stability. In mammalian cells, HJs are processed by the BTR (BLM-topoisomerase IIIα-RMI1-RMI2) complex, the SLX-MUS (SLX1-SLX4-MUS81-EME1) complex, and the GEN1 resolvase. Recent studies have linked the deficiency of one or more of these enzymes to perturbed DNA replication, impaired crosslink repair, chromosomal instability, and defective mitoses, coupled with the transmission of widespread DNA damage and high levels of mortality. We review these key advances and how they have cemented the status of HJ-processing enzymes as guardians of genome integrity and viability in mammalian cells. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Regulation of tissue repair and regeneration by electric fields

    Institute of Scientific and Technical Information of China (English)

    WANG En-tong; ZHAO Min

    2010-01-01

    Endogenous electric fields(Efs)have been detected at wounds and damaged tissues.The potential roles of Efs in tissue repair and regeneration have been an intriguing topic for centuries.Recent researches have provided significant insights into how naturally occurring Efs may participate in the control of tissue repair and regeneration.Applied Efs equivalent to the size of fields measured in vivo direct cell migration,cell proliferation and nerve sprouting at wounds.More remarkably,physiological Efs are a guidance cue that directs cell migration which overrides other well accepted directional signals including initial injury stimulation,wound void,contact inhibition release,population pressure and chemotaxis.Efs activate many intracellular signaling pathways in a directional manner.Modulation of endogenous wound Efs affects epithelial cell migration,cell proliferation,and nerve growth at cornea wounds in vivo.Electric stimulation is being tested clinically for the treatments of bone fracture,wound healing and spinal cord injury.Efs thus may represent a novel type of signaling paradigm in tissue repair and regeneration.Combination of the electric stimulation and other well understood biochemical regulatory mechanisms may offer powerful and effective therapies for tissue repair and regeneration.This review introduces experimental evidence for the existence of endogenous Efs and discusses their roles in tissue repair and regeneration.

  1. Regulation of tissue repair and regeneration by electric fields.

    Science.gov (United States)

    Wang, En-tong; Zhao, Min

    2010-02-01

    Endogenous electric fields (EFs) have been detected at wounds and damaged tissues. The potential roles of EFs in tissue repair and regeneration have been an intriguing topic for centuries. Recent researches have provided significant insights into how naturally occurring EFs may participate in the control of tissue repair and regeneration. Applied EFs equivalent to the size of fields measured in vivo direct cell migration, cell proliferation and nerve sprouting at wounds. More remarkably, physiological EFs are a guidance cue that directs cell migration which overrides other well accepted directional signals including initial injury stimulation, wound void, contact inhibition release, population pressure and chemotaxis. EFs activate many intracellular signaling pathways in a directional manner. Modulation of endogenous wound EFs affects epithelial cell migration, cell proliferation, and nerve growth at cornea wounds in vivo. Electric stimulation is being tested clinically for the treatments of bone fracture, wound healing and spinal cord injury. EFs thus may represent a novel type of signaling paradigm in tissue repair and regeneration. Combination of the electric stimulation and other well understood biochemical regulatory mechanisms may offer powerful and effective therapies for tissue repair and regeneration. This review introduces experimental evidence for the existence of endogenous EFs and discusses their roles in tissue repair and regeneration.

  2. Emerging roles of deubiquitinating enzymes in human cancer1

    Institute of Scientific and Technical Information of China (English)

    Jin-ming YANG

    2007-01-01

    Protein modifications by the covalent linkage of ubiquitin have significant in-volvement in many cellular processes, including stress response, oncogenesis,viral infection, transcription, protein turnover, organelle biogenesis, DNA repair,cellular differentiation, and cell cycle control. Protein ubiquitination and subse-quent degradation by the proteasome require the participation of both ubiquitinating enzymes and deubiquitinating enzymes. Although deubiquitinatingenzymes constitute a large family in the ubiquitin system, the study of this class of proteins is still in its infant stage. Recent studies have revealed a variety of molecular and biological functions of deubiquitinating enzymes and their associa-tion with human diseases. In this review we will discuss the possible roles that deubiquitinating enzymes may play in cancers.

  3. DSB (Im)mobility and DNA repair compartmentalization in mammalian cells.

    Science.gov (United States)

    Lemaître, Charlène; Soutoglou, Evi

    2015-02-13

    Chromosomal translocations are considered as causal in approximately 20% of cancers. Therefore, understanding their mechanisms of formation is crucial in the prevention of carcinogenesis. The first step of translocation formation is the concomitant occurrence of double-strand DNA breaks (DSBs) in two different chromosomes. DSBs can be repaired by different repair mechanisms, including error-free homologous recombination (HR), potentially error-prone non-homologous end joining (NHEJ) and the highly mutagenic alternative end joining (alt-EJ) pathways. Regulation of DNA repair pathway choice is crucial to avoid genomic instability. In yeast, DSBs are mobile and can scan the entire nucleus to be repaired in specialized DNA repair centers or if they are persistent, in order to associate with the nuclear pores or the nuclear envelope where they can be repaired by specialized repair pathways. DSB mobility is limited in mammals; therefore, raising the question of whether the position at which a DSB occurs influences its repair. Here, we review the recent literature addressing this question. We first present the reports describing the extent of DSB mobility in mammalian cells. In a second part, we discuss the consequences of non-random gene positioning on chromosomal translocations formation. In the third part, we discuss the mobility of heterochromatic DSBs in light of our recent data on DSB repair at the nuclear lamina, and finally, we show that DSB repair compartmentalization at the nuclear periphery is conserved from yeast to mammals, further pointing to a role for gene positioning in the outcome of DSB repair. When regarded as a whole, the different studies reviewed here demonstrate the importance of nuclear architecture on DSB repair and reveal gene positioning as an important parameter in the study of tumorigenesis.

  4. 49 CFR 1242.42 - Administration, repair and maintenance, machinery repair, equipment damaged, dismantling retired...

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Administration, repair and maintenance, machinery repair, equipment damaged, dismantling retired property, fringe benefits, other casualties and insurance... maintenance, machinery repair, equipment damaged, dismantling retired property, fringe benefits,...

  5. Cotton cellulose: enzyme adsorption and enzymic hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Beltrame, P.L.; Carniti, P.; Focher, B.; Marzetti, A.; Cattaneo, M.

    1982-01-01

    The adsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton cellulose samples was studied in the framework of the Langmuir approach at 2-8 degrees. The saturation amount of adsorbed enzyme was related to the susceptibility of the substrates to hydrolysis. In every case the adsorption process was faster by 2-3 orders of magnitude than the hydrolysis step to give end products. For ZnCl/sub 2/-treated cotton cellulose the Langmuir parameters correlated fairly well with the value of the Michaelis constant, measured for its enzymic hydrolysis, and the adsorptive complex was indistinguishable from the complex of the Michaelis-Menten model for the hydrolysis.

  6. Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking

    DEFF Research Database (Denmark)

    Nandi, S; Yu, J; Reinert, Line;

    2006-01-01

    leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative...

  7. Structural and functional conservation of two human homologs of the yeast DNA repair gene RAD6.

    NARCIS (Netherlands)

    M.H.M. Koken (Marcel); P. Reynolds (Paul); I. Jaspers-Dekker (Iris); L. Prakash; S. Prakash; D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1991-01-01

    textabstractThe RAD6 gene of Saccharomyces cerevisiae encodes a ubiquitin-conjugating enzyme (E2) that is required for DNA repair, damage-induced mutagenesis, and sporulation. We have cloned the two human RAD6 homologs, designated HHR6A and HHR6B. The two 152-amino acid human proteins share 95% sequ

  8. Effects of Remote Ischemic Preconditioning on Heme Oxygenase-1 Expression and Cutaneous Wound Repair

    NARCIS (Netherlands)

    Cremers, Niels A. J.; Wever, Kimberley E.; Wong, Ronald J.; van Rheden, Rene E. M.; Vermeij, Eline A.; van Dam, Gooitzen M.; Carels, Carine E. L.; Lundvig, Ditte M. S.; Wagener, Frank A D T G

    2017-01-01

    Skin wounds may lead to scar formation and impaired functionality. Remote ischemic preconditioning (RIPC) can induce the anti-inflammatory enzyme heme oxygenase-1 (HO-1) and protect against tissue injury. We aim to improve cutaneous wound repair by RIPC treatment via induction of HO-1. RIPC was

  9. The effect of aging on the DNA damage and repair capacity in 2BS cells undergoing oxidative stress.

    Science.gov (United States)

    Wang, Jin-Ling; Wang, Pei-Chang

    2012-01-01

    Aging is associated with a reduction in the DNA repair capacity under oxidative stress. However, whether the DNA damage and repair capacity can be a biomarker of aging remains controversial. In this study, we demonstrated two cause-and-effect relationships, the one is between the DNA damage and repair capacity and the cellular age, another is between DNA damage and repair capacity and the level of oxidative stress in human embryonic lung fibroblasts (2BS) exposed to different doses of hydrogen peroxide (H2O2). To clarify the mechanisms of the age-related reduction in DNA damage and repair capacity, we preliminarily evaluated the expressions of six kinds of pivotal enzymes involved in the two classical DNA repair pathways. The DNA repair capacity was observed in human fibroblasts cells using the comet assay; the age-related DNA repair enzymes were selected by RT-PCR and then verified by Western blot in vitro. Results showed that the DNA repair capacity was negatively and linearly correlated with (i) cumulative population doubling (PD) levels only in the group of low concentration of hydrogen peroxide treatment, (ii) with the level of oxidative stress only in the group of young PD cells. The mRNA expression of DNA polymerase δ1 decreased substantially in senescent cells and showed negative linear-correlation with PD levels; the protein expression level was well consistent with the mRNA level. Taken together, DNA damage and repair capacity can be a biomarker of aging. Reduced expression of DNA polymerase δ1 may be responsible for the decrease of DNA repair capacity in senescent cells.

  10. Manipulating DNA repair for improved genetic engineering in Aspergillus

    DEFF Research Database (Denmark)

    Nødvig, Christina Spuur

    engineering strategies. Chapter 1 gives an introduction to the genus Aspergillus and some of the tools relevant to fungal genetic engineering. It also contains a short introduction to DNA repair and its interplay with gene targeting and finally an overview over the different genome editing technologies......Aspergillus is a genus of filamentous fungi, which members includes industrial producers of enzymes, organic acids and secondary metabolites, important pathogens and a model organism. As such no matter the specific area of interest there are many reasons to perform genetic engineering, whether...... it is metabolic engineering to create better performing cell factory, elucidating pathways to study secondary metabolism etc. In this thesis, the main focus is on different ways to manipulate DNA repair for optimizing gene targeting, ultimately improving the methods available for faster and better genetic...

  11. Age-related neuronal degeneration: complementary roles of nucleotide excision repair and transcription-coupled repair in preventing neuropathology.

    Directory of Open Access Journals (Sweden)

    Dick Jaarsma

    2011-12-01

    Full Text Available Neuronal degeneration is a hallmark of many DNA repair syndromes. Yet, how DNA damage causes neuronal degeneration and whether defects in different repair systems affect the brain differently is largely unknown. Here, we performed a systematic detailed analysis of neurodegenerative changes in mouse models deficient in nucleotide excision repair (NER and transcription-coupled repair (TCR, two partially overlapping DNA repair systems that remove helix-distorting and transcription-blocking lesions, respectively, and that are associated with the UV-sensitive syndromes xeroderma pigmentosum (XP and Cockayne syndrome (CS. TCR-deficient Csa(-/- and Csb(-/- CS mice showed activated microglia cells surrounding oligodendrocytes in regions with myelinated axons throughout the nervous system. This white matter microglia activation was not observed in NER-deficient Xpa(-/- and Xpc(-/- XP mice, but also occurred in Xpd(XPCS mice carrying a point mutation (G602D in the Xpd gene that is associated with a combined XPCS disorder and causes a partial NER and TCR defect. The white matter abnormalities in TCR-deficient mice are compatible with focal dysmyelination in CS patients. Both TCR-deficient and NER-deficient mice showed no evidence for neuronal degeneration apart from p53 activation in sporadic (Csa(-/-, Csb(-/- or highly sporadic (Xpa(-/-, Xpc(-/- neurons and astrocytes. To examine to what extent overlap occurs between both repair systems, we generated TCR-deficient mice with selective inactivation of NER in postnatal neurons. These mice develop dramatic age-related cumulative neuronal loss indicating DNA damage substrate overlap and synergism between TCR and NER pathways in neurons, and they uncover the occurrence of spontaneous DNA injury that may trigger neuronal degeneration. We propose that, while Csa(-/- and Csb(-/- TCR-deficient mice represent powerful animal models to study the mechanisms underlying myelin abnormalities in CS, neuron

  12. Advancements in the maintenance of skin barrier/skin lipid composition and the involvement of metabolic enzymes.

    Science.gov (United States)

    Cui, Le; Jia, Yan; Cheng, Zhi-Wei; Gao, Ying; Zhang, Gao-Lei; Li, Jing-Yi; He, Cong-Fen

    2016-12-01

    The human skin barrier has an important role in protection and defense, reflected not only in the ability to resist entry of harmful substances into the human body, but also in the ability to prevent loss of water and nutrients. Once the skin barrier is damaged, the skin may become dry, scaly, and wrinkled, and a series of skin problems may occur. In this article, we review the composition of lipids, such as ceramides, cholesterol, and free fatty acids, in the skin and examine the expression of enzymes related to lipid metabolism, such as kallikreins, elongase of elongation of very long-chain fatty acids, hydrolases, and lipid synthases. Additionally, we discuss the involvement of these proteins in skin barrier function and structure. The information presented in this review is expected to provide a theoretical basis for the development of skin care products facilitating the maintenance and repair of skin barrier function. © 2016 Wiley Periodicals, Inc.

  13. DNA Repair and the Accumulation of Oxidatively Damaged DNA Are Affected by Fruit Intake in Mice

    DEFF Research Database (Denmark)

    Croteau, Deborah L; de Souza-Pinto, Nadja C; Harboe, Charlotte

    2010-01-01

    Aging is associated with elevated oxidative stress and DNA damage. To achieve healthy aging, we must begin to understand how diet affects cellular processes. We postulated that fruit-enriched diets might initiate a program of enhanced DNA repair and thereby improve genome integrity. C57Bl/6 J mice...... were fed for 14 weeks a control diet or a diet with 8% peach or nectarine extract. The activities of DNA repair enzymes, the level of DNA damage, and gene expression changes were measured. Our study showed that repair of various oxidative DNA lesions was more efficient in liver extracts derived from......-fed mice. Taken together, these results suggest that an increased intake of fruits might modulate the efficiency of DNA repair, resulting in altered levels of DNA damage....

  14. Percieved functions of naturally occurring autobiographical memories

    DEFF Research Database (Denmark)

    Treebak, L. S.; Henriksen, J. R.; Lundhus, S.

    2005-01-01

    The main empirical reference on functions of autobiographical memories is still Hyman & Faries (1992) who used the cue-word-method and retrospective judgements. We used diaries to sample naturally occurring autobiographical memories and participants? perceived use of these. Results partly replicate...

  15. Ostensible enzyme promiscuity: alkene cleavage by peroxidases.

    Science.gov (United States)

    Mutti, Francesco G; Lara, Miguel; Kroutil, Markus; Kroutil, Wolfgang

    2010-12-17

    Enzyme promiscuity is generally accepted as the ability of an enzyme to catalyse alternate chemical reactions besides the 'natural' one. In this paper peroxidases were shown to catalyse the cleavage of a C=C double bond adjacent to an aromatic moiety for selected substrates at the expense of molecular oxygen at an acidic pH. It was clearly shown that the reaction occurs due to the presence of the enzyme; furthermore, the reactivity was clearly linked to the hemin moiety of the peroxidase. Comparison of the transformations catalysed by peroxidase and by hemin chloride revealed that these two reactions proceed equally fast; additional experiments confirmed that the peptide backbone was not obligatory for the reaction and only a single functional group of the enzyme was required, namely in this case the prosthetic group (hemin). Consequently, we propose to define such a promiscuous activity as 'ostensible enzyme promiscuity'. Thus, we call an activity that is catalysed by an enzyme 'ostensible enzyme promiscuity' if the reactivity can be tracked back to a single catalytic site, which on its own can already perform the reaction equally well in the absence of the peptide backbone.

  16. [Production of ligninolytic enzymes in bioreactor].

    Science.gov (United States)

    Gao, Da-wen; Wen, Xiang-hua; Qian, Yi

    2006-02-01

    Production of ligninolytic enzymes under nitrogen limited conditions(C/N = 56/2.2) was studied in a 5-L stirred tank bioreactor with a working volume of 2 L for obtaining higher production of ligninolytic enzymes by white rot fungus Phanerochaete chrysosporium BKM-F-1767 and its control strategy. Results show that the manganese peroxidase (MnP) and laccase (Lac) reached peak at the sixth day and the seventh day, respectively, and the variation of them with time in a batch cultivation are similar to the results by agitated Erlenmeyer flasks; however higher enzyme activity was not achieved by applying a fed-batch strategy, in which nitrogen limited medium was fed to the reactor. In addition, variation of pH during cultivation was related to the growth of P. chrysosporium and enzymes production during both batch and fed-batch cultivation. The pH value of liquid medium began to decline when the enzyme activity occurred in the system, and the decline became more and more slow along with the decrease of enzyme activity at the end of fermentation. So, pH would be as a control parameter to find out the growth of P. chrysosporium and enzymes production during incubating P. chrysosporium. However, fed-batch strategy still need further study.

  17. The EBI enzyme portal.

    Science.gov (United States)

    Alcántara, Rafael; Onwubiko, Joseph; Cao, Hong; Matos, Paula de; Cham, Jennifer A; Jacobsen, Jules; Holliday, Gemma L; Fischer, Julia D; Rahman, Syed Asad; Jassal, Bijay; Goujon, Mikael; Rowland, Francis; Velankar, Sameer; López, Rodrigo; Overington, John P; Kleywegt, Gerard J; Hermjakob, Henning; O'Donovan, Claire; Martín, María Jesús; Thornton, Janet M; Steinbeck, Christoph

    2013-01-01

    The availability of comprehensive information about enzymes plays an important role in answering questions relevant to interdisciplinary fields such as biochemistry, enzymology, biofuels, bioengineering and drug discovery. At the EMBL European Bioinformatics Institute, we have developed an enzyme portal (http://www.ebi.ac.uk/enzymeportal) to provide this wealth of information on enzymes from multiple in-house resources addressing particular data classes: protein sequence and structure, reactions, pathways and small molecules. The fact that these data reside in separate databases makes information discovery cumbersome. The main goal of the portal is to simplify this process for end users.

  18. Enzyme molecules as nanomotors.

    Science.gov (United States)

    Sengupta, Samudra; Dey, Krishna K; Muddana, Hari S; Tabouillot, Tristan; Ibele, Michael E; Butler, Peter J; Sen, Ayusman

    2013-01-30

    Using fluorescence correlation spectroscopy, we show that the diffusive movements of catalase enzyme molecules increase in the presence of the substrate, hydrogen peroxide, in a concentration-dependent manner. Employing a microfluidic device to generate a substrate concentration gradient, we show that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, we induce the migration of catalase toward glucose oxidase, thereby showing that chemically interconnected enzymes can be drawn together.

  19. Dorsal variant blister aneurysm repair.

    Science.gov (United States)

    Couldwell, William T; Chamoun, Roukoz

    2012-01-01

    Dorsal variant proximal carotid blister aneurysms are treacherous lesions to manage. It is important to recognize this variant on preoperative angiographic imaging, in anticipation of surgical strategies for their treatment. Strategies include trapping the involved segment and revascularization if necessary. Other options include repair of the aneurysm rupture site directly. Given that these are not true berry aneurysms, repair of the rupture site involves wrapping or clip-grafting techniques. The case presented here was a young woman with a subarachnoid hemorrhage from a ruptured dorsal variant blister aneurysm. The technique used is demonstrated in the video and is a modified clip-wrap technique using woven polyester graft material. The patient was given aspirin preoperatively as preparation for the clip-wrap technique. It is the authors' current protocol to attempt a direct repair with clip-wrapping and leaving artery sacrifice with or without bypass as a salvage therapy if direct repair is not possible. Assessment of vessel patency after repair is performed by intraoperative Doppler and indocyanine green angiography. Intraoperative somatosensory and motor evoked potential monitoring is performed in all cases. The video can be found here: http://youtu.be/crUreWGQdGo.

  20. Cure shrinkage in epoxy grouts for grouted repairs

    Science.gov (United States)

    Shamsuddoha, Md.; Islam, Md. Mainul; Aravinthan, Thiru; Manalo, Allan; Lau, Kin-tak

    2013-08-01

    Structures can go through harsh environmental adversity and can experience material loss and cracks during their service lives. Infill material is used to ensure a supporting bed for a grouted repair. Epoxy grouts are used for repairing and rehabilitating structures, such as foundations, bridges, piers, transportation pipelines, etc., because they are resistant to typical chemicals and possess superior mechanical properties than other grouts. The resin based infill used inside the void or cracked space of the repair is vulnerable to shrinkage. When these filled grouts have high resin content, cracks can develop from residual stresses, which can affect the load transfer performance. It follows that interlayer separation and cracking of infill layer can occur in a grouted repair. In this study, volumetric shrinkage of two epoxy grouts was measured over 28 days using a Pycnometer. The highest volumetric shrinkage measured after 7 days was found to be 2.72%. The results suggest that the volumetric shrinkage can be reduced to 1.1% after 7 days, through the introduction of a coarse aggregate filler; a 2.5 times reduction in shrinkage. About 98% and 92% of the total shrinkage over the 28 day period, of the unfilled and filled grouts respectively, was found to occur within 7 days of mixing. The gel-time shrinkages were also calculated, to determine the "postgel" part of the curing contraction which subsequently produces residual stresses in the hardened grout systems.

  1. Autonomic Self-Repairing Glassy Materials

    Energy Technology Data Exchange (ETDEWEB)

    Coillot, D.; Mear, F.O.; Montagne, L. [Univ Lille Nord France, CNRS, Unite Catalyse and Chim Solide, UMR 8181, F-59652 Villeneuve Dascq (France); Podor, R. [CEA Marcoule, CNRS UM2 ENSCM, Inst Chim Separat Marcoule, UMR 5257, 30 (France)

    2010-07-01

    A new process that enables glassy materials to self-repair from mechanical damage is presented in this paper. Contrary to intrinsic self-healing, which involves overheating to enable crack healing by glass softening, this process is based on an extrinsic effect produced by vanadium boride (VB) particles dispersed within the glass matrix. Self-repair is obtained through the oxidation of VB particles, and thus without the need to increase the operating temperature. The VB healing agent is selected for its capacity to oxidize at a lower temperature than the softening point of the glass. Thermogravimetric analyses indeed show that VB oxidation is rapid and occurs below the glass transition temperature. Solid-state nuclear magnetic resonance spectroscopy indicates that VB is oxidized into V{sub 2}O{sub 5} and B{sub 2}O{sub 3}, which enable the local formation of glass. The autonomic self-healing effect is demonstrated by an in situ experiment visualized using an environmental scanning electron microscope. It is shown that a crack could be healed by the VB oxidation products. (authors)

  2. The Roles of Several Residues of Escherichia coli DNA Photolyase in the Highly Efficient Photo-Repair of Cyclobutane Pyrimidine Dimers

    Directory of Open Access Journals (Sweden)

    Lei Xu

    2010-01-01

    Full Text Available Escherichia coli DNA photolyase is an enzyme that repairs the major kind of UV-induced lesions, cyclobutane pyrimidine dimer (CPD in DNA utilizing 350–450 nm light as energy source. The enzyme has very high photo-repair efficiency (the quantum yield of the reaction is ~0.85, which is significantly greater than many model compounds that mimic photolyase. This suggests that some residues of the protein play important roles in the photo-repair of CPD. In this paper, we have focused on several residues discussed their roles in catalysis by reviewing the existing literature and some hypotheses.

  3. Rare complication after totally extraperitoneal endoscopic inguinal hernia repair: Small bowel perforation without peritoneal disruption.

    Science.gov (United States)

    Kojima, Shigehiro; Sakamoto, Tsuguo; Honda, Masayuki; Nishiguchi, Ryohei; Ogawa, Fumihiro

    2016-11-01

    We report a rare case of visceral injury after totally extraperitoneal endoscopic inguinal hernia repair. A 48-year-old man underwent needlescopic totally extraperitoneal repair of a direct inguinal hernia. Bleeding from a branch of the inferior epigastric vessels occurred at the beginning of the extraperitoneal dissection with a monopolar electrosurgical device. Hemostasis was prolonged. However, herniorrhaphy and mesh repair were successfully performed, and no peritoneal disruption or pneumoperitoneum was visible. The patient was discharged home on the next day. However, 30 h after this operation, he underwent diagnostic and operative laparoscopy because of acute abdominal pain. Ileal perforation was found and repaired, and pathological examination indicated cautery artifact. Thus, thermal damage to the ileum during the initial operation may have caused the bowel perforation. To the best of our knowledge, no other cases of bowel perforation after totally extraperitoneal repair without peritoneal disruption have been reported.

  4. Enzymes in Analytical Chemistry.

    Science.gov (United States)

    Fishman, Myer M.

    1980-01-01

    Presents tabular information concerning recent research in the field of enzymes in analytic chemistry, with methods, substrate or reaction catalyzed, assay, comments and references listed. The table refers to 128 references. Also listed are 13 general citations. (CS)

  5. Enzymic lactose hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.J.; Brand, J.C.

    1980-01-01

    Acid or enzymic hydrolysis can be used to hydrolyze lactose. Advantages of both are compared and details of enzymic hydrolysis using yeast or fungal enzymes given. The new scheme outlined involves recycling lactase. Because lactose and lactase react to ultrafiltration (UF) membranes differently separation is possible. Milk or milk products are ultrafiltered to separate a concentrate from a lactose-rich permeate which is treated with lactase in a reactor until hydrolysis reaches a required level. The lactase can be removed by UF as it does not permeate the membrane, and it is recycled back to the reactor. Permeate from the second UF stage may or may not be recombined with the concentrate from the first stage to produce a low lactose product (analysis of a typical low-lactose dried whole milk is given). Batch or continuous processes are explained and a batch process without enzyme recovery is discussed. (Refs. 4).

  6. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    . In this thesis, separations using crossflow elecro-membrane filtration (EMF) of amino acids, bovine serum albumin (BSA) and industrial enzymes from Novozymes were performed. The main objective of this study was to investigate the technological feasibility of EMF in the application of industrial enzyme...... fractionation, such as removal of a side activity from the main enzyme activity. As a proof-of-concept, amino acids were used as model solution to test the feasibility of EMF in the application of amphoteric molecule separation. A single amino acid was used to illustrate the effect of an electric field...... on the separation performance were very small in the investigated range. The mass transport of each enzyme can be well explained by the Extended-Nernst-Planck equation. Better separation was observed at lower feed concentration, higher solution pH in the investigated range and with a polysulfone (PS) MF membrane...

  7. Indicators: Sediment Enzymes

    Science.gov (United States)

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  8. Starch Biorefinery Enzymes.

    Science.gov (United States)

    Läufer, Albrecht

    2017-03-07

    Nature uses enzymes to build and convert biomass; mankind uses the same enzymes and produces them on a large scale to make optimum use of biomass in biorefineries. Bacterial α-amylases and fungal glucoamylases have been the workhorses of starch biorefineries for many decades. Pullulanases were introduced in the 1980s. Proteases, cellulases, hemicellulases, and phytases have been on the market for a few years as process aids, improving yields, performance, and costs. Detailed studies of the complex chemical structures of biomass and of the physicochemical limitations of industrial biorefineries have led enzyme developers to produce novel tailor-made solutions for improving yield and profitability in the industry. This chapter reviews the development of enzyme applications in the major starch biorefining processes.

  9. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    . In this thesis, separations using crossflow elecro-membrane filtration (EMF) of amino acids, bovine serum albumin (BSA) and industrial enzymes from Novozymes were performed. The main objective of this study was to investigate the technological feasibility of EMF in the application of industrial enzyme...... fractionation, such as removal of a side activity from the main enzyme activity. As a proof-of-concept, amino acids were used as model solution to test the feasibility of EMF in the application of amphoteric molecule separation. A single amino acid was used to illustrate the effect of an electric field...... on the separation performance were very small in the investigated range. The mass transport of each enzyme can be well explained by the Extended-Nernst-Planck equation. Better separation was observed at lower feed concentration, higher solution pH in the investigated range and with a polysulfone (PS) MF membrane...

  10. Ethical issues occurring within nursing education.

    Science.gov (United States)

    Fowler, Marsha D; Davis, Anne J

    2013-03-01

    The large body of literature labeled "ethics in nursing education" is entirely devoted to curricular matters of ethics education in nursing schools, that is, to what ought to be the ethics content that is taught and what theory or issues ought to be included in all nursing curricula. Where the nursing literature actually focuses on particular ethical issues, it addresses only single topics. Absent from the literature, however, is any systematic analysis and explication of ethical issues or dilemmas that occur within the context of nursing education. The objective of this article is to identify the spectrum of ethical issues in nursing education to the end of prompting a systematic and thorough study of such issues, and to lay the groundwork for research by identifying and provisionally typologizing the ethical issues that occur within the context of academic nursing.

  11. RNA-modifying enzymes.

    Science.gov (United States)

    Ferré-D'Amaré, Adrian R

    2003-02-01

    A bewildering number of post-transcriptional modifications are introduced into cellular RNAs by enzymes that are often conserved among archaea, bacteria and eukaryotes. The modifications range from those with well-understood functions, such as tRNA aminoacylation, to widespread but more mysterious ones, such as pseudouridylation. Recent structure determinations have included two types of RNA nucleobase modifying enzyme: pseudouridine synthases and tRNA guanine transglycosylases.

  12. Overproduction of ligninolytic enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Elisashvili, Vladimir; Kachlishvili, Eva; Torok, Tamas

    2014-06-17

    Methods, compositions, and systems for overproducing ligninolytic enzymes from the basidiomycetous fungus are described herein. As described, the method can include incubating a fungal strain of Cerrena unicolor IBB 303 in a fermentation system having growth medium which includes lignocellulosic material and then cultivating the fungal strain in the fermentation system under conditions wherein the fungus expresses the ligninolytic enzymes. In some cases, the lignocellulosic material is mandarin peel, ethanol production residue, walnut pericarp, wheat bran, wheat straw, or banana peel.

  13. Molten Metal Explosions are Still Occurring

    Science.gov (United States)

    2009-02-01

    pans which can give rise to Force 2 incidents if unheated or contain foreign matter. Handling hot dross represents a particular hazard. Force 3...explosions have occurred from hot dross transfer, cooling and dumping into storage areas. In one recent incident, an employee reportedly dumped a load of...thermiting dross into a water puddle and was fatally burned. Casting: Incidents continue to be reported for dc casting arising from bleed-outs

  14. Low recurrence rate of a two-layered closure repair for primary and recurrent midline incisional hernia without mesh

    NARCIS (Netherlands)

    A.H.M. Dur (Alfons); D. den Hartog (Dennis); W.E. Tuinebreijer (Wim); R.W. Kreis (Robert); J.F. Lange (Johan)

    2009-01-01

    textabstractBackground: Incisional hernia is a serious complication after abdominal surgery and occurs in 11-23% of laparotomies. Repair can be done, for instance, with a direct suture technique, but recurrence rates are high. Recent literature advises the use of mesh repair. In contrast to this dev

  15. 46 CFR 167.65-70 - Reports of accidents, repairs, and unsafe boilers and machinery by engineers.

    Science.gov (United States)

    2010-10-01

    ... machinery by engineers. 167.65-70 Section 167.65-70 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... of accidents, repairs, and unsafe boilers and machinery by engineers. (a) Before making repairs to a... shall be the duty of all engineers when an accident occurs to the boilers or machinery in their...

  16. Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution.

    Science.gov (United States)

    Hu, Jinchuan; Adar, Sheera; Selby, Christopher P; Lieb, Jason D; Sancar, Aziz

    2015-05-01

    We developed a method for genome-wide mapping of DNA excision repair named XR-seq (excision repair sequencing). Human nucleotide excision repair generates two incisions surrounding the site of damage, creating an ∼30-mer. In XR-seq, this fragment is isolated and subjected to high-throughput sequencing. We used XR-seq to produce stranded, nucleotide-resolution maps of repair of two UV-induced DNA damages in human cells: cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine-pyrimidone photoproducts [(6-4)PPs]. In wild-type cells, CPD repair was highly associated with transcription, specifically with the template strand. Experiments in cells defective in either transcription-coupled excision repair or general excision repair isolated the contribution of each pathway to the overall repair pattern and showed that transcription-coupled repair of both photoproducts occurs exclusively on the template strand. XR-seq maps capture transcription-coupled repair at sites of divergent gene promoters and bidirectional enhancer RNA (eRNA) production at enhancers. XR-seq data also uncovered the repair characteristics and novel sequence preferences of CPDs and (6-4)PPs. XR-seq and the resulting repair maps will facilitate studies of the effects of genomic location, chromatin context, transcription, and replication on DNA repair in human cells.

  17. In Vitro Comparison of the Bond Strength between Ceramic Repair Systems and Ceramic Materials and Evaluation of the Wettability.

    Science.gov (United States)

    Kocaağaoğlu, Hasan; Manav, Taha; Albayrak, Haydar

    2017-04-01

    When fracture of an all-ceramic restoration occurs, it can be necessary to repair without removing the restoration. Although there are many studies about the repair of metal-ceramic restorations, there are few about all-ceramic restorations. The aim of this study was to evaluate the shear bond strength between ceramic repair systems and esthetic core materials and to evaluate the wettability of all-ceramic core materials. Disk-like specimens (N = 90) made of three dental ceramic infrastructure materials (zirconia ceramic, alumina ceramic, glass ceramic) were polished with silicon carbide paper, prepared for bonding (abrasion with 30 μm diamond rotary cutting instrument). Thirty specimens of each infrastructure were obtained. Each infrastructure group was divided into three subgroups; they were bonded using 3 repair systems: Bisco Intraoral Repair Kit, Cimara & Cimara Zircon Repair System, and Clearfil Repair System. After 1200 thermocycles, shear bond strength was measured in a universal testing machine at a 0.5 mm/min crosshead speed. In addition, the contact angle values of the infrastructures after surface treatments were examined for wettability. Data were analyzed by using ANOVA and Tukey post hoc tests. Although there were no significant differences among the repair systems (p > 0.05) in the glass ceramic and zirconia groups, a significant difference was found among the repair systems in alumina infrastructure (p 0.05); however, a statistically significant difference was found among the repair systems (p < 0.05). No difference was found among the infrastructures and repair systems in terms of contact angle values. Cimara & Cimara Zircon Repair System had higher bond strength values than the other repair systems. Although no difference was found among the infrastructures and repair systems, contact wettability angle was decreased by surface treatments compared with polished surfaces. © 2015 by the American College of Prosthodontists.

  18. Lumbar hernia repaired using a new technique.

    Science.gov (United States)

    Di Carlo, Isidoro; Toro, Adriana; Sparatore, Francesca; Corsale, Giuseppe

    2007-01-01

    Lumbar hernia is uncommon and occurs in Grynfeltt's triangle on the left side, more frequently in men than in women. Acquired lumbar hernias are the result of iliac crest bone harvest or blunt trauma and seat belt injuries in road accidents. Many surgical options have been reported for repairing this hernia through primary closure of the defect or through use of aponeurotic or prosthetic materials. The Dowd technique is the technique most often used. The authors describe a patient with posttraumatic inferior triangle lumbar hernia who underwent laparoscopy and, 10 days later, laparotomy. Both procedures failed. Finally, a novel lumbotomic surgical approach was used, involving the Dowd technique and prosthetic mesh. The patient was free of recurrence 3 months after the procedure.

  19. Self-repairable polymeric networks: Synthesis and network design

    Science.gov (United States)

    Ghosh, Biswajit

    This dissertation describes the design, synthesis and development of a new class of polymeric networks that exhibit self-repairing properties under UV exposure. It consists of two parts: (a) modification and synthesis of oxetane (OXE), and oxolane (OXO) substituted chitosan (CHI) macromonomer, and (b) design, and synthesis of self-repairing polyurethane (PUR) networks consisting of modified chitosan. Unmodified CHI consisting of acetamide (-NHCOCH3), primary hydroxyl (-OH), and amine (-NH2) functional groups were reacted with OXE or OXO compounds under basic conditions in order to substitute the 1° --OH groups, and at the same time, convert -NHCOCH 3 functionalities into -NH2 groups, while maintaining their un-reacted form to generate OXE/OXO-substituted CHI macromonomer. These substituted CHI macromonomers were incorporated within the PUR backbone by reacting with trifunctional isocyanate in the presence of polyethylene glycol (PEG) and dibutyl tin dilaurate catalyst (DBTDL). Utilizing spectroscopic analysis combined with optical microscopy, these studies showed that the kinetics of self-repair depends on the stoichiometry of the individual entities as well as the time required for self-repairing to occur decrease with increasing OXE quantity within the network. Internal reflection infrared imaging (IRIRI) of OXE/OXO-CHI-PUR networks as well as Raman and Fourier transform IR (FT-IR) studies of OXE/OXO-CHI macromonomers revealed that cationic OXE/OXO ring opening, free radical polyurea (PUA)-to-PUR conversion, along with chair-to-boat conformational changes of CHI backbone are responsible for repairing the damaged network. The network remodeling process, investigated by utilizing micro-thermal analyzer (muTA), revealed that mechanical damage generates small fragments or oligomers within the scratch, therefore glass transition temperature (Tg) decreases, and under UV exposure cross-linking reactions propagate from the bottom of the scratch to the top resulting in

  20. Additive manufacturing for in situ repair of osteochondral defects

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Daniel L; Lipton, Jeffrey I; Bonassar, Lawrence J; Lipson, Hod, E-mail: dlc44@cornell.ed, E-mail: jil26@cornell.ed, E-mail: lb244@cornell.ed, E-mail: hod.lipson@cornell.ed [Cornell University, Mechanical and Aerospace Engineering, Ithaca, NY (United States)

    2010-09-15

    Tissue engineering holds great promise for injury repair and replacement of defective body parts. While a number of techniques exist for creating living biological constructs in vitro, none have been demonstrated for in situ repair. Using novel geometric feedback-based approaches and through development of appropriate printing-material combinations, we demonstrate the in situ repair of both chondral and osteochondral defects that mimic naturally occurring pathologies. A calf femur was mounted in a custom jig and held within a robocasting-based additive manufacturing (AM) system. Two defects were induced: one a cartilage-only representation of a grade IV chondral lesion and the other a two-material bone and cartilage fracture of the femoral condyle. Alginate hydrogel was used for the repair of cartilage; a novel formulation of demineralized bone matrix was used for bone repair. Repair prints for both defects had mean surface errors less than 0.1 mm. For the chondral defect, 42.8 {+-} 2.6% of the surface points had errors that were within a clinically acceptable error range; however, with 1 mm path planning shift, an estimated {approx}75% of surface points could likely fall within the benchmark envelope. For the osteochondral defect, 83.6 {+-} 2.7% of surface points had errors that were within clinically acceptable limits. In addition to implications for minimally invasive AM-based clinical treatments, these proof-of-concept prints are some of the only in situ demonstrations to-date, wherein the substrate geometry was unknown a priori. The work presented herein demonstrates in situ AM, suggests potential biomedical applications and also explores in situ-specific issues, including geometric feedback, material selection and novel path planning techniques.

  1. Nucleotide excision repair in the test tube.

    NARCIS (Netherlands)

    N.G.J. Jaspers (Nicolaas); J.H.J. Hoeijmakers (Jan)

    1995-01-01

    textabstractThe eukaryotic nucleotide excision-repair pathway has been reconstituted in vitro, an achievement that should hasten the full enzymological characterization of this highly complex DNA-repair pathway.

  2. Biological Augmentation of Rotator Cuff Tendon Repair

    National Research Council Canada - National Science Library

    Kovacevic, David; Rodeo, Scott A

    2008-01-01

    A histologically normal insertion site does not regenerate following rotator cuff tendon-to-bone repair, which is likely due to abnormal or insufficient gene expression and/or cell differentiation at the repair site...

  3. Cleft lip and palate repair - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000004.htm Cleft lip and palate repair - discharge To use the sharing ... Elsevier Saunders; 2015:chap 8. Read More Cleft lip and palate Cleft lip and palate repair Review Date 5/9/ ...

  4. Abdominal aortic aneurysm repair - open - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000240.htm Abdominal aortic aneurysm repair - open - discharge To use the sharing features ... References Orandi BJ, Black JH. Open repair of abdominal aortic aneurysms. In: Cameron JL, Cameron AM, eds. Current Surgical ...

  5. Naturally occurring radionuclides and Earth sciences

    Directory of Open Access Journals (Sweden)

    G. Ferrara

    1997-06-01

    Full Text Available Naturally occurring radionuclides are used in Earth sciences for two fundamental purposes: age determination of rocks and minerals and studies of variation of the isotopic composition of radiogenic nuclides. The methodologies that are in use today allow us to determine ages spanning from the Earth's age to the late Quaternary. The variations of isotopic composition of radiogenic nuclides can be applied to problems of mantle evolution, magma genesis and characterization with respect to different geodynamic situations and can provide valuable information not obtainable by elemental geochemistry.

  6. Immobilization of enzymes using non-ionic colloidal liquid aphrons (CLAs): Surface and enzyme effects.

    Science.gov (United States)

    Ward, Keeran; Xi, Jingshu; Stuckey, David C

    2015-12-01

    The use of non-ionic colloidal liquid aphrons (CLAs) as a support for enzyme immobilisation was investigated. Formulation required the mixing of an aqueous-surfactant solution with a relatively non-polar solvent-surfactant solution, forming a solvent droplet surrounded by a thin stabilised aqueous film (soapy shell). Studies utilising anionic surfactants have showed increased retention, however, very little have been understood about the forces governing immobilisation. This study seeks to determine the effects of enzyme properties on CLA immobilisation by examining a non-ionic/non-polar solvent system comprised of two non-ionic surfactants, Tween 20 and 80, mineral oil and the enzymes lipase, aprotinin and α-chymotrypsin. From these results it was deduced that hydrophobic interactions strongly governed immobilisation. Confocal Scanning Laser Microscopy (CSLM) revealed that immobilisation was predominantly achieved by surface adsorption attributed to hydrophobic interactions between the enzyme and the CLA surface. Enzyme surface affinity was found to increase when added directly to the formulation (pre-manufacture addition), as opposed to the bulk continuous phase (post-manufacture addition), with α-chymotrypsin and aprotinin being the most perturbed, while lipase was relatively unaffected. The effect of zeta potential on immobilisation showed that enzymes adsorbed better closer to their pI, indicating that charge minimisation was necessary for immobilisation. Finally, the effect of increasing enzyme concentration in the aqueous phase resulted in an increase in adsorption for all enzymes due to cooperativity between protein molecules, with saturation occurring faster at higher adsorption rates.

  7. Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes.

    Science.gov (United States)

    Wei, Hui; Wang, Erkang

    2013-07-21

    Over the past few decades, researchers have established artificial enzymes as highly stable and low-cost alternatives to natural enzymes in a wide range of applications. A variety of materials including cyclodextrins, metal complexes, porphyrins, polymers, dendrimers and biomolecules have been extensively explored to mimic the structures and functions of naturally occurring enzymes. Recently, some nanomaterials have been found to exhibit unexpected enzyme-like activities, and great advances have been made in this area due to the tremendous progress in nano-research and the unique characteristics of nanomaterials. To highlight the progress in the field of nanomaterial-based artificial enzymes (nanozymes), this review discusses various nanomaterials that have been explored to mimic different kinds of enzymes. We cover their kinetics, mechanisms and applications in numerous fields, from biosensing and immunoassays, to stem cell growth and pollutant removal. We also summarize several approaches to tune the activities of nanozymes. Finally, we make comparisons between nanozymes and other catalytic materials (other artificial enzymes, natural enzymes, organic catalysts and nanomaterial-based catalysts) and address the current challenges and future directions (302 references).

  8. Studies on bleomycin-induced repair DNA synthesis in permeable mouse ascites sarcoma cells.

    Directory of Open Access Journals (Sweden)

    Mori,Shigeru

    1989-04-01

    Full Text Available To study the mechanism of DNA excision repair, a DNA repair system employing permeable mouse sarcoma (SR-C3H/He cells was established and characterized. SR-C3H/He cells were permeabilized with a 0.0175% Triton X-100 solution. The permeable cells were treated with 1 mM ATP and 0.11 mM bleomycin, and then washed thoroughly to remove ATP and bleomycin. Repair DNA synthesis occurred in the bleomycin-damaged, permeable SR-C3H/He cells when incubated with ATP and four deoxyribonucleoside triphosphates. The repair nature of the DNA synthesis was confirmed by the BrdUMP density shift technique, and by the reduced sensitivity of the newly synthesized DNA to Escherichia coli exonuclease III. The DNA synthesis was optimally enhanced by addition of 0.08 M NaCl. Studies using selective inhibitors of DNA synthesis showed that aphidicolin-sensitive DNA polymerase (DNA polymerase alpha and/or delta and DNA polymerase beta were involved in the repair process. The present DNA repair system is thought to be useful to study nuclear DNA damage by bleomycin, removal of the damaged ends by an exonuclease, repair DNA synthesis by DNA polymerases and repair patch ligation by DNA ligase(s.

  9. Deletion-bias in DNA double-strand break repair differentially contributes to plant genome shrinkage.

    Science.gov (United States)

    Vu, Giang T H; Cao, Hieu X; Reiss, Bernd; Schubert, Ingo

    2017-02-28

    In order to prevent genome instability, cells need to be protected by a number of repair mechanisms, including DNA double-strand break (DSB) repair. The extent to which DSB repair, biased towards deletions or insertions, contributes to evolutionary diversification of genome size is still under debate. We analyzed mutation spectra in Arabidopsis thaliana and in barley (Hordeum vulgare) by PacBio sequencing of three DSB-targeted loci each, uncovering repair via gene conversion, single strand annealing (SSA) or nonhomologous end-joining (NHEJ). Furthermore, phylogenomic comparisons between A. thaliana and two related species were used to detect naturally occurring deletions during Arabidopsis evolution. Arabidopsis thaliana revealed significantly more and larger deletions after DSB repair than barley, and barley displayed more and larger insertions. Arabidopsis displayed a clear net loss of DNA after DSB repair, mainly via SSA and NHEJ. Barley revealed a very weak net loss of DNA, apparently due to less active break-end resection and easier copying of template sequences into breaks. Comparative phylogenomics revealed several footprints of SSA in the A. thaliana genome. Quantitative assessment of DNA gain and loss through DSB repair processes suggests deletion-biased DSB repair causing ongoing genome shrinking in A. thaliana, whereas genome size in barley remains nearly constant.

  10. Speech Repairs, Intonational Boundaries and Discourse Markers Modeling Speakers' Utterances in Spoken Dialog

    CERN Document Server

    Heeman, P A

    1999-01-01

    In this thesis, we present a statistical language model for resolving speech repairs, intonational boundaries and discourse markers. Rather than finding the best word interpretation for an acoustic signal, we redefine the speech recognition problem to so that it also identifies the POS tags, discourse markers, speech repairs and intonational phrase endings (a major cue in determining utterance units). Adding these extra elements to the speech recognition problem actually allows it to better predict the words involved, since we are able to make use of the predictions of boundary tones, discourse markers and speech repairs to better account for what word will occur next. Furthermore, we can take advantage of acoustic information, such as silence information, which tends to co-occur with speech repairs and intonational phrase endings, that current language models can only regard as noise in the acoustic signal. The output of this language model is a much fuller account of the speaker's turn, with part-of-speech ...

  11. Double-strand break repair on sex chromosomes: challenges during male meiotic prophase.

    Science.gov (United States)

    Lu, Lin-Yu; Yu, Xiaochun

    2015-01-01

    During meiotic prophase, DNA double-strand break (DSB) repair-mediated homologous recombination (HR) occurs for exchange of genetic information between homologous chromosomes. Unlike autosomes or female sex chromosomes, human male sex chromosomes X and Y share little homology. Although DSBs are generated throughout male sex chromosomes, homologous recombination does not occur for most regions and DSB repair process is significantly prolonged. As a result, male sex chromosomes are coated with many DNA damage response proteins and form a unique chromatin structure known as the XY body. Interestingly, associated with the prolonged DSB repair, transcription is repressed in the XY body but not in autosomes, a phenomenon known as meiotic sex chromosome inactivation (MSCI), which is critical for male meiosis. Here using mice as model organisms, we briefly summarize recent progress on DSB repair in meiotic prophase and focus on the mechanism and function of DNA damage response in the XY body.

  12. PARP-1: Friend or Foe of DNA Damage and Repair in Tumorigenesis?

    Energy Technology Data Exchange (ETDEWEB)

    Swindall, Amanda F.; Stanley, Jennifer A. [Department of Radiation Oncology Comprehensive Cancer Center, University of Alabama at Birmingham School of Medicine, 176F HSROC Suite 2232B, 1700 6th Avenue South, Birmingham, AL 35249 (United States); Yang, Eddy S., E-mail: eyang@uab.edu [Department of Radiation Oncology Comprehensive Cancer Center, University of Alabama at Birmingham School of Medicine, 176F HSROC Suite 2232B, 1700 6th Avenue South, Birmingham, AL 35249 (United States); Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35249 (United States); Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35249 (United States)

    2013-07-26

    Oxidative stress induced by reactive oxygen species can result in DNA damage within cells and subsequently increase risk for carcinogenesis. This may be averted by repair of DNA damage through the base or nucleotide excision repair (BER/NER) pathways. PARP, a BER protein, is known for its role in DNA-repair. However, multiple lesions can occur within a small range of DNA, known as oxidative clustered DNA lesions (OCDLs), which are difficult to repair and may lead to the more severe DNA double-strand break (DSB). Inefficient DSB repair can then result in increased mutagenesis and neoplastic transformation. OCDLs occur more frequently within a variety of tumor tissues. Interestingly, PARP is highly expressed in several human cancers. Additionally, chronic inflammation may contribute to tumorigenesis through ROS-induced DNA damage. Furthermore, PARP can modulate inflammation through interaction with NFκB and regulating the expression of inflammatory signaling molecules. Thus, the upregulation of PARP may present a double-edged sword. PARP is needed to repair ROS-induced DNA lesions, but PARP expression may lead to increased inflammation via upregulation of NFκB signaling. Here, we discuss the role of PARP in the repair of oxidative damage versus the formation of OCDLs and speculate on the feasibility of PARP inhibition for the treatment and prevention of cancers by exploiting its role in inflammation.

  13. A network of cancer genes with co-occurring and anti-co-occurring mutations.

    Directory of Open Access Journals (Sweden)

    Qinghua Cui

    Full Text Available Certain cancer genes contribute to tumorigenesis in a manner of either co-occurring or mutually exclusive (anti-co-occurring mutations; however, the global picture of when, where and how these functional interactions occur remains unclear. This study presents a systems biology approach for this purpose. After applying this method to cancer gene mutation data generated from large-scale and whole genome sequencing of cancer samples, a network of cancer genes with co-occurring and anti-co-occurring mutations was constructed. Analysis of this network revealed that genes with co-occurring mutations prefer direct signaling transductions and that the interaction relations among cancer genes in the network are related with their functional similarity. It was also revealed that genes with co-occurring mutations tend to have similar mutation frequencies, whereas genes with anti-co-occurring mutations tend to have different mutation frequencies. Moreover, genes with more exons tend to have more co-occurring mutations with other genes, and genes having lower local coherent network structures tend to have higher mutation frequency. The network showed two complementary modules that have distinct functions and have different roles in tumorigenesis. This study presented a framework for the analysis of cancer genome sequencing outputs. The presented data and uncovered patterns are helpful for understanding the contribution of gene mutations to tumorigenesis and valuable in the identification of key biomarkers and drug targets for cancer.

  14. Repair of Late Retrograde Type A Aortic Dissection After TEVAR: Causes and Management.

    Science.gov (United States)

    Mosquera, Victor X; Marini, Milagros; Fraga-Manteiga, Daniel; Gulias, Daniel; Cuenca, Jose J

    2016-03-01

    One of the most feared complications of thoracic endovascular aortic repair (TEVAR) and hybrid arch repair is retrograde type A aortic dissection (RTAD). More than two-thirds of RTAD occurs in the immediate postoperative period and first postoperative month. In presentations beyond that point, progression of the native aortopathy must be considered. We report a late presentation of an RTAD seven months after hybrid repair of an aortic intramural hematoma with an ulcer-like projection, and review the causes and management of this TEVAR complication.

  15. Transvesicoscopic Repair of Vesicovaginal Fistula

    Directory of Open Access Journals (Sweden)

    R. B. Nerli

    2010-01-01

    Full Text Available Introduction. Vesicovaginal fistula has been a social and surgical problem for centuries. Many surgical techniques have been developed to correct this abnormality, including transabdominal, transvaginal, and endoscopic approaches. The best approach is probably the one with which the surgeon feels most experienced and comfortable. Laparoscopy has become increasingly popular in urology, reducing the invasiveness of treatment and shortening the period of convalescence. We report our results of transvesicoscopic approach for VVF repair. Materials and Methods. Patients with VVF were offered repair using the transvesicoscopic route. With the patient under general anaesthesia and in modified lithotomy position cystoscopy was performed with gas insufflation. Under cystoscopic guidance the bladder was fixed to anterior abdominal wall and ports inserted into the bladder. The fistula was repaired under endoscopic vision. Results. Four women, who had VVF following abdominal hysterectomy, underwent this procedure. The operating time ranged from 175 to 235 minutes. There was minimal bleeding. Post operative complications included ileus in one and fever in another. No recurrence of VVF was noted in any patient. Conclusions. Transvesicoscopic repair of VVF is feasible, safe, and results in lower morbidity and quicker recovery time.

  16. Small Crater Expedient Repair Test.

    Science.gov (United States)

    1980-08-01

    Force Base, New Mexico , October 1975. 3. Rollings, Raymond S., Laboratory Evaluation of Expedient Pavement Repair Materials, CEEDO-TR-7-44, Civil and...blank) APPENDIX A EQUIPMENT PERFORMANCE SP6WCIFICATIONS Performance specit’ications are included i.n tl is appe udi \\ tor the following equipment: 1

  17. Outcome of quadriceps tendon repair.

    Science.gov (United States)

    Puranik, Gururaj S; Faraj, Adnan

    2006-04-01

    Complete rupture of the quadriceps tendon is a well-described injury. There is a scarcity of literature relating to the outcome of patients with this injury after surgery. We undertook a retrospective analysis of patients who had surgical repair of their quadriceps tendon at our institution over a 13-year period, totalling 21 patients. Males were more commonly affected, with a male/female ratio of 4:1. The peak incidence was in the sixth decade of life. Assessment consisted of the completion of a functional knee questionnaire and a clinical examination. Symptomatic outcome following surgical repair was good with a mean symptom score generated of 19.16 out of a maximum of 25 using the Rougraff et al scoring system. Most of the patients returned to their pre-injury level of activity. Five degrees deficit and extension lag was present in three patients; these patients had the quadriceps repaired using transosseous sutures. Patients who had direct repair of the tendon using the Bunnell technique had lower Rougraff scores than the rest.

  18. How the Brain Repairs Stuttering

    Science.gov (United States)

    Kell, Christian A.; Neumann, Katrin; von Kriegstein, Katharina; Posenenske, Claudia; von Gudenberg, Alexander W.; Euler, Harald; Giraud, Anne-Lise

    2009-01-01

    Stuttering is a neurodevelopmental disorder associated with left inferior frontal structural anomalies. While children often recover, stuttering may also spontaneously disappear much later after years of dysfluency. These rare cases of unassisted recovery in adulthood provide a model of optimal brain repair outside the classical windows of…

  19. Microwave Oven Repair. Teacher Edition.

    Science.gov (United States)

    Smreker, Eugene

    This competency-based curriculum guide for teachers addresses the skills a technician will need to service microwave ovens and to provide customer relations to help retain the customer's confidence in the product and trust in the service company that performs the repair. The guide begins with a task analysis, listing 20 cognitive tasks and 5…

  20. Pure robotic retrocaval ureter repair

    Directory of Open Access Journals (Sweden)

    Ashok k. Hemal

    2008-12-01

    Full Text Available PURPOSE: To demonstrate the feasibility of pure robotic retrocaval ureter repair. MATERIALS AND METHODS: A 33 year old female presented with right loin pain and obstruction on intravenous urography with the classical "fish-hook" appearance. She was counseled on the various methods of repair and elected to have a robot assisted repair. The following steps are performed during a pure robotic retrocaval ureter repair. The patient is placed in a modified flank position, pneumoperitoneum created and ports inserted. The colon is mobilized to expose the retroperitoneal structures: inferior vena cava, right gonadal vein, right ureter, and duodenum. The renal pelvis and ureter are mobilized and the renal pelvis transected. The ureter is transposed anterior to the inferior vena cava and a pyelopyelostomy is performed over a JJ stent. RESULTS: This patient was discharged on postoperative day 3. The catheter and drain tube were removed on day 1. Her JJ stent was removed at 6 weeks postoperatively. The postoperative intravenous urography at 3 months confirmed normal drainage of contrast medium. CONCLUSION: Pure robotic retrocaval ureter is a feasible procedure; however, there does not appear to be any great advantage over pure laparoscopy, apart from the ergonomic ease for the surgeon as well the simpler intracorporeal suturing.

  1. [Complications of inguinal hernia repair].

    Science.gov (United States)

    Forte, A; D'Urso, A; Gallinaro, L S; Lo Storto, G; Bosco, M R; Vietri, F; Beltrami, V

    2002-03-01

    It's shown by literature and confirmed by Author's experience that, on account of the excellent results, prosthetic repair of inguinal hernia is more effective than "conventional" (Bassini, Mc Vay, Shouldice). Between January 1993 and December 2000 were observed 875 patients with inguinal hernia (814 monolateral, 61 bilateral); all patients underwent a Lichtenstein repair both in the primary version and in its variations (internal ring plastic, trasversalis plicate, plug repair). The patients were discharged from hospital within 24 hours after surgery in 90% of cases. No important intraoperative complications were observed; the patients restarting work varied from 3 to 15 days after the discharging in relation to patient anxiety, onset of complications and to the type of work. The complications observed were: urine retention (1.6%), superficial haematoma (1.3%), superficial infection (1%), wound suppuration (0.5%), serous effusion (0.7%), postsurgery pain (2.1%), scrotal edema (1.7%), persistent inguinal neuralgia (0.6), local hypoesthesia (4.3%), ischemical orchitis (0.1%), recurrence (0.2%). In conclusion Authors assert that "tension free" repair allows optimal results both for the surgery point (easiness of the technique, repeatability, less invasivity, scanty incident of recurrences, low frequency of postoperative complications) and in economic terms, allowing an early mobilization of the patients. A further improvement would be obtained with more care in surgical and patient management, with more excellent results.

  2. Random-walk enzymes.

    Science.gov (United States)

    Mak, Chi H; Pham, Phuong; Afif, Samir A; Goodman, Myron F

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C→U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  3. Random-walk enzymes

    Science.gov (United States)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  4. Random-walk enzymes

    Science.gov (United States)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-01-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C → U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics. PMID:26465508

  5. Enzymic saccharification of pretreated wheat straw.

    Science.gov (United States)

    Vallander, L; Eriksson, K E

    1985-05-01

    Studies of pretreatment of wheat and its subsequent saccharification by Trichoderma reesei cellulases are reported. Steam explosion was found to be the most effective of the pretreatment methods tested. Data are presented describing the effect of enzyme and substrate concentration on the rate and degree of hydrolysis. Significant inhibition of the cellulases was observed when sugar concentrations were 6% or higher. This inhibition increased when glucose and ethanol were present simultaneously. Adsorption of enzymes to the substrate was followed during a 24-h hydrolysis period. An initial rapid and extensive adsorption occurred, followed by a short desorption period that was followed in turn by a further increased adsorption peaking after 3 h. Intermediate removal of hydrolysate, particularly in combination with a second addition of enzyme, clearly improved the yield of saccharification compared to an uninterrupted hydrolysis over a 24-h period. Thus, a 74% yield of reducing sugars was obtained. Furthermore, an increase in the amount of recoverable enzymes was observed under these conditions. Evidence is presented that suggests that a countercurrent technique, whereby free enzymes in recovered hydrolysate are adsorbed onto new substrate, may provide a means of recirculating dissolved enzymes.

  6. Fix-It Careers: Jobs in Repair

    Science.gov (United States)

    Torpey, Elka Maria

    2010-01-01

    From auto mechanic to HVAC technicians, many occupations require repair skills. For jobseekers with the right skills, there are many advantages to a repair career. Repair work provides millions of jobs throughout the United States. Wages are often higher than average. And in many occupations, the employment outlook is bright. Plus, most repair…

  7. 30 CFR 57.6801 - Vehicle repair.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Vehicle repair. 57.6801 Section 57.6801 Mineral... and Underground § 57.6801 Vehicle repair. Vehicles containing explosive material and oxidizers shall not be taken into a repair garage or shop....

  8. Nationwide prevalence of groin hernia repair

    DEFF Research Database (Denmark)

    Burcharth, Jakob; Pedersen, Michael; Bisgaard, Thue;

    2013-01-01

    Groin hernia repair is a commonly performed surgical procedure in the western world but large-scaled epidemiologic data are sparse. Large-scale data on the occurrence of groin hernia repair may provide further understanding to the pathophysiology of groin hernia development. This study was undert...... was undertaken to investigate the age and gender dependent prevalence of groin hernia repair....

  9. REPAIR MECHANISM IN FOREIGN LANGUAGE CLASSROOM INTERACTION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents practical research on repair mechanismand its four repair trajectories in FL classroom interaction. Thisshows that it is effective and efficient in assisting FL learners todevelop their communicative competence and understand theprocess of language acquisition. Repair strategies that are ofgreat value to FL teachers in FL classroom teaching are also ex-pounded.

  10. Isolated HAGL lesion after arthroscopic Bankart repair in a professional soccer player.

    Science.gov (United States)

    Celik, Haluk; Seckin, Mustafa Faik; Kara, Adnan; Akman, Senol

    2017-05-01

    Post-traumatic anterior shoulder instability commonly occurs following an avulsion of capsulolabral complex from glenoid (Bankart lesion) or rarely after humeral avulsion of the glenohumeral ligaments (HAGL lesion). Arthroscopic Bankart repair offers high success rates of healing. However, trauma following the treatment may cause implant failure or re-avulsion of the treated tissue. We aim to present the diagnosis and treatment of an isolated HAGL lesion in a professional soccer player who had previously undergone arthroscopic Bankart repair.

  11. Influence of LET on repair of DNA damages in Deinococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Y.; Tanaka, A.; Kikuchi, M.; Shimizu, T.; Watanabe, H. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Cao, J.P.; Taucher-Scholz, G.

    1997-03-01

    Inactivation caused by heavy ions was studied in dry cells of radioresistant bacterium Deinococcus radiodurans. All survival curves were characterized by a large shoulder of the curves. No final slopes of the exponential part of survival curves for heavy ion irradiation were steeper than that for 2.0 MeV electron irradiation. The plots of RBE versus LET showed no obvious peaks, suggesting that this bacterium can repair not only DNA double strand breaks (DSBs) but also clustered damage in DNA which may be induced by heavy ions. The genomic DNA of D. radiodurans was cleaved into large fragments with restriction enzyme Not I after post-irradiation incubation and the fragments were separated using pulsed-field gel electrophoresis (PFGE). DSBs induction and rejoining process were analyzed by detection of the reappearance of ladder pattern of DNA fragments. The required repair time after heavy ions irradiation was longer than the repair time for electrons at the same dose of irradiation, however, the rate of repair enzyme induction was almost similar to each other between electrons and heavy ions, suggesting that the same repair system is likely to be used after both low and high LET irradiations. (author)

  12. UbcH7 regulates 53BP1 stability and DSB repair.

    Science.gov (United States)

    Han, Xiangzi; Zhang, Lei; Chung, Jinsil; Mayca Pozo, Franklin; Tran, Amanda; Seachrist, Darcie D; Jacobberger, James W; Keri, Ruth A; Gilmore, Hannah; Zhang, Youwei

    2014-12-09

    DNA double-strand break (DSB) repair is not only key to genome stability but is also an important anticancer target. Through an shRNA library-based screening, we identified ubiquitin-conjugating enzyme H7 (UbcH7, also known as Ube2L3), a ubiquitin E2 enzyme, as a critical player in DSB repair. UbcH7 regulates both the steady-state and replicative stress-induced ubiquitination and proteasome-dependent degradation of the tumor suppressor p53-binding protein 1 (53BP1). Phosphorylation of 53BP1 at the N terminus is involved in the replicative stress-induced 53BP1 degradation. Depletion of UbcH7 stabilizes 53BP1, leading to inhibition of DSB end resection. Therefore, UbcH7-depleted cells display increased nonhomologous end-joining and reduced homologous recombination for DSB repair. Accordingly, UbcH7-depleted cells are sensitive to DNA damage likely because they mainly used the error-prone nonhomologous end-joining pathway to repair DSBs. Our studies reveal a novel layer of regulation of the DSB repair choice and propose an innovative approach to enhance the effect of radiotherapy or chemotherapy through stabilizing 53BP1.

  13. Enzyme recycling in lignocellulosic biorefineries

    DEFF Research Database (Denmark)

    Jørgensen, Henning; Pinelo, Manuel

    2017-01-01

    platform. Cellulases are the most important enzymes required in this process, but the complex nature of lignocellulose requires several other enzymes (hemicellulases and auxiliary enzymes) for efficient hydrolysis. Enzyme recycling increases the catalytic productivity of the enzymes by reusing them...... upscaled and tested in industrial settings, mainly because of many difficulties with recycling of enzymes from the complex lignocellulose hydrolyzate at industrially relevant conditions, i.e., high solids loadings. The challenges are associated with the large number of different enzymes required...... for efficient hydrolysis, enzyme stability, and the detrimental interaction between enzyme and lignin. This review provides a comprehensive overview of the various methods for enzyme recovery and recycling, for example recycling of free enzymes, readsorption to fresh material, recycling of solids, membrane...

  14. BIOCONVERSION OF NATURALLY-OCCURRING PRECURSORS AND RELATED SYNTHETIC COMPOUNDS USING PLANT-CELL CULTURES

    NARCIS (Netherlands)

    PRAS, N

    1992-01-01

    The nearly unlimited enzymatic potential of cultured plant cells can basically be employed for bioconversion purposes. Plant enzymes are able to catalyze regio- and stereospecific reactions and can therefore be applied to the production of compounds of pharmaceutical interest. Naturally occurring as

  15. Translational control of an intestinal microvillar enzyme

    DEFF Research Database (Denmark)

    Danielsen, E M; Cowell, G M; Sjöström, H

    1986-01-01

    The rates of biosynthesis of adult and foetal pig small-intestinal aminopeptidase N (EC 3.4.11.2) were compared to determine at which level the expression of the microvillar enzyme is developmentally controlled. In organ-cultured explants, the rate of biosynthesis of foetal aminopeptidase N is only...... about 3% of the adult rate. The small amount synthesized occurs in a high-mannose-glycosylated, membrane-bound, form that is processed to the mature, complex-glycosylated, form at a markedly slower rate than that of the adult enzyme. Extracts of total RNA from adult and foetal intestine contained...

  16. REPAIR TECHNOLOGY IMPROVEMENT OF SPECIALIZED FREIGHT CARS

    Directory of Open Access Journals (Sweden)

    V. M. Bubnov

    2016-02-01

    Full Text Available Purpose. The volume of cargo transportation demands the introduction of a new generation of cars that would be able to provide all the needs of carriers. But this is impossible without the implementation of renovation repair facilities with the introduction of new technologies and modernization of the repair process. Repair of rolling stock is a key factor that must proceed with the establishment of new cars, as not all of the inventions may be repaired in car-repair depots, most of which are obsolete. The purpose is to analyze the possibility of increasing the efficiency of the repair process by introducing new repair technologies or improving the existing ones. It will improve not only the quality of the repair, but also its rate. Methodology. Works on improving the designs of freight cars are held by many design organizations in almost all industrialized countries. It makes repair organizations (depots and car-repair plants to upgrade the repair process. Achievements of-this goal is possible by improving the technology renovation and reorganization through the use of flexible flow technologies, which to date are the most effective in the repair of rolling stock. Findings. When performing the analysis it was determined that there are different designs of cars. More of cars are all-purpose and their repair does not cause difficulties for car-repair business. However, the number of specialized cars is also significant, and the technology of their repair should be improved. One of the reasons is that many models, such as tank wagons for the carriage of sulfur, are intended for the carriage of dangerous goods and their failure at the time of motion is not permitted. Originality. Firstly the authors have defined direction at improving technologies of repair specialized cars. Practical value. Actual improvement in the construction of cars is to improve the existing repair facilities. In addition, the repair technology using nowadays when repairing

  17. Tetrahydroberberine, a pharmacologically active naturally occurring alkaloid.

    Science.gov (United States)

    Pingali, Subramanya; Donahue, James P; Payton-Stewart, Florastina

    2015-04-01

    Tetrahydroberberine (systematic name: 9,10-dimethoxy-5,8,13,13a-tetrahydro-6H-benzo[g][1,3]benzodioxolo[5,6-a]quinolizine), C20H21NO4, a widely distributed naturally occurring alkaloid, has been crystallized as a racemic mixture about an inversion center. A bent conformation of the molecule is observed, with an angle of 24.72 (5)° between the arene rings at the two ends of the reduced quinolizinium core. The intermolecular hydrogen bonds that play an apparent role in crystal packing are 1,3-benzodioxole -CH2···OCH3 and -OCH3···OCH3 interactions between neighboring molecules.

  18. Pilomyxoid Astrocytoma Occurring in the Third Ventricle

    Directory of Open Access Journals (Sweden)

    Sanghyeon Kim

    2015-01-01

    Full Text Available Pilomyxoid astrocytoma (PMA is a rare central nervous system tumor that has been included in the 2007 World Health Organization Classification of Tumors of the Central Nervous System. Due to its more aggressive behavior, PMA is classified as Grade II neoplasm by the World Health Organization. PMA predominantly affects the hypothalamic/chiasmatic region and occurs in children (mean age of occurrence = 10 months. We report a case of a 24-year-old man who presented with headache, nausea, and vomiting. Brain CT and MRI revealed a mass occupying only the third ventricle. We performed partial resection. Histological findings, including monophasic growth with a myxoid background, and absence of Rosenthal fibers or eosinophilic granular bodies, as well as the strong positivity for glial fibrillary acidic protein were consistent with PMA.

  19. Detection of Harmonic Occurring using Kalman Filtering

    DEFF Research Database (Denmark)

    Hussain, Dil Muhammad Akbar; Shoro, Ghulam Mustafa; Imran, Raja Muhammed

    2014-01-01

    As long as the load to a power system is linear which has been the case before 80's, typically no harmonics are produced. However, the modern power electronic equipment for controlled power consumption produces harmonic disturbances, these devices/equipment possess nonlinear voltage/current chara...... using Kalman filter. This may be very useful for example to quickly switching on certain filters based on the harmonic present. We are using a unique technique to detect the occurrence of harmonics......./current characteristic. These harmonics are not to be allowed to grow beyond a certain limit to avoid any grave consequence to the customer’s main supply. Filters can be implemented at the power source or utility location to eliminate these harmonics. In this paper we detect the instance at which these harmonics occur...

  20. Preparation of metagenomic libraries from naturally occurring marine viruses.

    Science.gov (United States)

    Solonenko, Sergei A; Sullivan, Matthew B

    2013-01-01

    Microbes are now well recognized as major drivers of the biogeochemical cycling that fuels the Earth, and their viruses (phages) are known to be abundant and important in microbial mortality, horizontal gene transfer, and modulating microbial metabolic output. Investigation of environmental phages has been frustrated by an inability to culture the vast majority of naturally occurring diversity coupled with the lack of robust, quantitative, culture-independent methods for studying this uncultured majority. However, for double-stranded DNA phages, a quantitative viral metagenomic sample-to-sequence workflow now exists. Here, we review these advances with special emphasis on the technical details of preparing DNA sequencing libraries for metagenomic sequencing from environmentally relevant low-input DNA samples. Library preparation steps broadly involve manipulating the sample DNA by fragmentation, end repair and adaptor ligation, size fractionation, and amplification. One critical area of future research and development is parallel advances for alternate nucleic acid types such as single-stranded DNA and RNA viruses that are also abundant in nature. Combinations of recent advances in fragmentation (e.g., acoustic shearing and tagmentation), ligation reactions (adaptor-to-template ratio reference table availability), size fractionation (non-gel-sizing), and amplification (linear amplification for deep sequencing and linker amplification protocols) enhance our ability to generate quantitatively representative metagenomic datasets from low-input DNA samples. Such datasets are already providing new insights into the role of viruses in marine systems and will continue to do so as new environments are explored and synergies and paradigms emerge from large-scale comparative analyses.

  1. Entropy and Enzyme Catalysis.

    Science.gov (United States)

    Åqvist, Johan; Kazemi, Masoud; Isaksen, Geir Villy; Brandsdal, Bjørn Olav

    2017-02-21

    The role played by entropy for the enormous rate enhancement achieved by enzymes has been debated for many decades. There are, for example, several confirmed cases where the activation free energy is reduced by around 10 kcal/mol due to entropic effects, corresponding to a rate enhancement of ∼10(7) compared to the uncatalyzed reaction. However, despite substantial efforts from both the experimental and theoretical side, no real consensus has been reached regarding the origin of such large entropic contributions to enzyme catalysis. Another remarkable instance of entropic effects is found in enzymes that are adapted by evolution to work at low temperatures, near the freezing point of water. These cold-adapted enzymes invariably show a more negative entropy and a lower enthalpy of activation than their mesophilic orthologs, which counteracts the exponential damping of reaction rates at lower temperature. The structural origin of this universal phenomenon has, however, remained elusive. The basic problem with connecting macroscopic thermodynamic quantities, such as activation entropy and enthalpy derived from Arrhenius plots, to the 3D protein structure is that the underlying detailed (microscopic) energetics is essentially inaccessible to experiment. Moreover, attempts to calculate entropy contributions by computer simulations have mostly focused only on substrate entropies, which do not provide the full picture. We have recently devised a new approach for accessing thermodynamic activation parameters of both enzyme and solution reactions from computer simulations, which turns out to be very successful. This method is analogous to the experimental Arrhenius plots and directly evaluates the temperature dependence of calculated reaction free energy profiles. Hence, by extensive molecular dynamics simulations and calculations of up to thousands of independent free energy profiles, we are able to extract activation parameters with sufficient precision for making

  2. Angiotensin-converting enzyme

    DEFF Research Database (Denmark)

    Sørensen, P G; Rømer, F K; Cortes, D

    1984-01-01

    In order to evaluate bleomycin-associated lung damage in humans, lung function parameters and serum levels of the endothelial-bound angiotensin-converting enzyme (ACE) were determined by serial measurements in 11 patients who were treated for testicular cancer. None developed clinical or radiolog......In order to evaluate bleomycin-associated lung damage in humans, lung function parameters and serum levels of the endothelial-bound angiotensin-converting enzyme (ACE) were determined by serial measurements in 11 patients who were treated for testicular cancer. None developed clinical...

  3. Establishing Maximal Medical Improvement After Arthroscopic Rotator Cuff Repair.

    Science.gov (United States)

    Zuke, William A; Leroux, Timothy S; Gregory, Bonnie P; Black, Austin; Forsythe, Brian; Romeo, Anthony A; Verma, Nikhil N

    2017-06-01

    As health care transitions from a pay-for-service to a pay-for-performance infrastructure, the value of orthopaedic care must be defined accurately. Significant efforts have been made in defining quality and cost in arthroplasty; however, there remains a lag in ambulatory orthopaedic care. Two-year follow-up has been a general requirement for reporting outcomes after rotator cuff repair. However, this time requirement has not been established scientifically and is of increasing importance in the era of value-based health care. Given that arthroscopic rotator cuff repair is a common ambulatory orthopaedic procedure, the purpose of this study was to establish a time frame for maximal medical improvement (the state when improvement has stabilized) after arthroscopic rotator cuff repair. Systematic review. A systematic review of the literature was conducted, identifying studies reporting sequential patient-reported outcomes up to a minimum of 2 years after arthroscopic rotator cuff repair. The primary clinical outcome was patient-reported outcomes at 3-month, 6-month, 1-year, and 2-year follow-up. Secondary clinical outcomes included range of motion, strength, retears, and complications. Clinically significant improvement was determined between various time intervals by use of the minimal clinically important difference. The review included 19 studies including 1370 patients who underwent rotator cuff repair. Clinically significant improvement in patient-reported outcomes was seen up to 1 year after rotator cuff repair, but no clinical significance was noted from 1 year to 2 years. The majority of improvement in strength and range of motion was seen up to 6 months, but no clinically meaningful improvement was seen thereafter. All reported complications and the majority of retears occurred within 6 months after rotator cuff repair. After rotator cuff repair, a clinically significant improvement in patient-reported outcomes, range of motion, and strength was seen up to 1

  4. Rapid Identification of Chemoresistance Mechanisms Using Yeast DNA Mismatch Repair Mutants.

    Science.gov (United States)

    Ojini, Irene; Gammie, Alison

    2015-07-21

    Resistance to cancer therapy is a major obstacle in the long-term treatment of cancer. A greater understanding of drug resistance mechanisms will ultimately lead to the development of effective therapeutic strategies to prevent resistance from occurring. Here, we exploit the mutator phenotype of mismatch repair defective yeast cells combined with whole genome sequencing to identify drug resistance mutations in key pathways involved in the development of chemoresistance. The utility of this approach was demonstrated via the identification of the known CAN1 and TOP1 resistance targets for two compounds, canavanine and camptothecin, respectively. We have also experimentally validated the plasma membrane transporter HNM1 as the primary drug resistance target of mechlorethamine. Furthermore, the sequencing of mitoxantrone-resistant strains identified inactivating mutations within IPT1, a gene encoding inositolphosphotransferase, an enzyme involved in sphingolipid biosynthesis. In the case of bactobolin, a promising anticancer drug, the endocytosis pathway was identified as the drug resistance target responsible for conferring resistance. Finally, we show that that rapamycin, an mTOR inhibitor previously shown to alter the fitness of the ipt1 mutant, can effectively prevent the formation of mitoxantrone resistance. The rapid and robust nature of these techniques, using Saccharomyces cerevisiae as a model organism, should accelerate the identification of drug resistance targets and guide the development of novel therapeutic combination strategies to prevent the development of chemoresistance in various cancers.

  5. Analysis of acetylation stoichiometry suggests that SIRT3 repairs nonenzymatic acetylation lesions.

    Science.gov (United States)

    Weinert, Brian T; Moustafa, Tarek; Iesmantavicius, Vytautas; Zechner, Rudolf; Choudhary, Chunaram

    2015-11-03

    Acetylation is frequently detected on mitochondrial enzymes, and the sirtuin deacetylase SIRT3 is thought to regulate metabolism by deacetylating mitochondrial proteins. However, the stoichiometry of acetylation has not been studied and is important for understanding whether SIRT3 regulates or suppresses acetylation. Using quantitative mass spectrometry, we measured acetylation stoichiometry in mouse liver tissue and found that SIRT3 suppressed acetylation to a very low stoichiometry at its target sites. By examining acetylation changes in the liver, heart, brain, and brown adipose tissue of fasted mice, we found that SIRT3-targeted sites were mostly unaffected by fasting, a dietary manipulation that is thought to regulate metabolism through SIRT3-dependent deacetylation. Globally increased mitochondrial acetylation in fasted liver tissue, higher stoichiometry at mitochondrial acetylation sites, and greater sensitivity of SIRT3-targeted sites to chemical acetylation in vitro and fasting-induced acetylation in vivo, suggest a nonenzymatic mechanism of acetylation. Our data indicate that most mitochondrial acetylation occurs as a low-level nonenzymatic protein lesion and that SIRT3 functions as a protein repair factor that removes acetylation lesions from lysine residues.

  6. Causes of recurrence in laparoscopic inguinal hernia repair

    Directory of Open Access Journals (Sweden)

    Kukleta Jan

    2006-01-01

    Full Text Available Aim: The analysis of possible mechanisms of repair failure is a necessary instrument and the best way to decrease the recurrence rate and improve the overall results. Avoiding historical errors and learning from the reported pitfalls and mistakes helps to standardize the relatively new laparoscopic techniques of trans-abdominal preperitoneal and total extraperitoneal. Materials and Methods: The video tapes of all primary laparoscopic repairs done by the author that led to recurrence were retrospectively analyzed and compared with findings at the second laparoscopic repair. A review of the available cases of recurrences occurring between 1994 and 2003 is the basis of this report. Summary: Adequate mesh size, porosity of mesh material, slitting of the mesh, correct and generous dissection of preperitoneal space and wrinkle-free placement of the mesh seem to be the more important factors in avoiding recurrence rather than strength of the material or strong penetrating fixation. Special attention should be paid to preperitoneal lipoma as a possible overlooked herniation or potential future pseudorecurrence despite nondislocated correctly positioned mesh. Conclusion: Laparoscopic hernia repair is a complex but very efficient method in experienced hands. To achieve the best possible results, it requires an acceptance of a longer learning curve, structured well-mentored training and high level of standardization of the operative procedure.

  7. Coordinated sensing and autonomous repair of pressure vessels and structures

    Science.gov (United States)

    Huston, Dryver R.; Hurley, David A.; Gollins, Kenneth; Gervais, Anthony

    2010-04-01

    Self-repairing structural systems can potentially improve performance ranges and lifetimes compared to those of conventional systems without self-healing capability. Self-healing materials have been used in automotive and aeronautical applications for over a century. The bulk of these systems operate by using the damage to directly initiate the repair response without any supervisory coordination. Integrating sensing and supervisory control technologies with self-healing may improve the safety and reliability of critical components and structures. This project used laboratory scale test beds to illustrate the benefit of an integrated sensing, control and self-healing system. A thermal healing polymer embedded with resistive heating wires acted as the sensing-healing material. Sensing duties were performed using an impedance, capacitance, and resistance testing device and a PC acted as the controller. As damage occurs to the polymer it is detected, located, and characterized. Based on the sensor signal, a decision is made as to whether to execute a repair and then to subsequently monitor the repair process to ensure completeness. The second demonstration was a self-sealing pressure vessel with integrated sensing and healing capability. These proof-of-concept prototypes can likely be expanded and improved with alternative sensor options, sensing-healing materials, and system architecture.

  8. Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking

    DEFF Research Database (Denmark)

    Nandi, S; Yu, J; Reinert, Line

    2006-01-01

    It has been hypothesized that defects in DNA-mismatch repair are associated with smoking in certain types of transformed non-Hodgkin lymphoma (NHL). We have analyzed biopsy samples from two indolent B-cell lymphomas, follicular lymphoma (FL) and chronic lymphocytic leukemia/small lymphocytic...... leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative...

  9. Chromatin Dynamics in Genome Stability: Roles in Suppressing Endogenous DNA Damage and Facilitating DNA Repair

    Directory of Open Access Journals (Sweden)

    Nidhi Nair

    2017-07-01

    Full Text Available Genomic DNA is compacted into chromatin through packaging with histone and non-histone proteins. Importantly, DNA accessibility is dynamically regulated to ensure genome stability. This is exemplified in the response to DNA damage where chromatin relaxation near genomic lesions serves to promote access of relevant enzymes to specific DNA regions for signaling and repair. Furthermore, recent data highlight genome maintenance roles of chromatin through the regulation of endogenous DNA-templated processes including transcription and replication. Here, we review research that shows the importance of chromatin structure regulation in maintaining genome integrity by multiple mechanisms including facilitating DNA repair and directly suppressing endogenous DNA damage.

  10. Immunochemical approach to the study of DNA repair. Proposed technical program and technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    A simple immunochemical assay to quantify DNA lesions is being developed in order to facilitate the study of DNA repair. Antibodies have been raised to 5,6-dihydroxy-dihydrothymine and to thymine dimers and these have been used to measure DNA damages produced by osmium tetroxide and ultraviolet light, respectively. An enzyme immunoassay has been developed and the sensitivity of this method will be compared to physical, enzymatic, and chemical methods using PM2 bacteriophage DNA. Finally DNA repair will be assayed in several model systems.

  11. Introduction to naturally occurring radioactive material

    Energy Technology Data Exchange (ETDEWEB)

    Egidi, P.

    1997-08-01

    Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. We are also bathed in a sea of natural radiation coming from the sun and deep space. Living systems have adapted to these levels of radiation and radioactivity. But some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. Other activities, such as flying at high altitudes, expose us to elevated levels of NORM. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose

  12. Introduction to naturally occurring radioactive material

    Energy Technology Data Exchange (ETDEWEB)

    Egidi, P.

    1997-08-01

    Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. We are also bathed in a sea of natural radiation coming from the sun and deep space. Living systems have adapted to these levels of radiation and radioactivity. But some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. Other activities, such as flying at high altitudes, expose us to elevated levels of NORM. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose

  13. Current Biomechanical Concepts for Rotator Cuff Repair

    Science.gov (United States)

    2013-01-01

    For the past few decades, the repair of rotator cuff tears has evolved significantly with advances in arthroscopy techniques, suture anchors and instrumentation. From the biomechanical perspective, the focus in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. To accomplish these objectives, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. In addition, the healing response may be compromised by intrinsic factors such as decreased vascularity, hypoxia, and fibrocartilaginous changes or aforementioned extrinsic compression factors. Furthermore, it is well documented that torn rotator cuff muscles have a tendency to atrophy and become subject to fatty infiltration which may affect the longevity of the repair. Despite all the aforementioned factors, initial fixation strength is an essential consideration in optimizing rotator cuff repair. Therefore, numerous biomechanical studies have focused on elucidating the strongest devices, knots, and repair configurations to improve contact characteristics for rotator cuff repair. In this review, the biomechanical concepts behind current rotator cuff repair techniques will be reviewed and discussed. PMID:23730471

  14. Ultrasound determination of rotator cuff tear repairability

    Science.gov (United States)

    Tse, Andrew K; Lam, Patrick H; Walton, Judie R; Hackett, Lisa

    2015-01-01

    Background Rotator cuff repair aims to reattach the torn tendon to the greater tuberosity footprint with suture anchors. The present study aimed to assess the diagnostic accuracy of ultrasound in predicting rotator cuff tear repairability and to assess which sonographic and pre-operative features are strongest in predicting repairability. Methods The study was a retrospective analysis of measurements made prospectively in a cohort of 373 patients who had ultrasounds of their shoulder and underwent rotator cuff repair. Measurements of rotator cuff tear size and muscle atrophy were made pre-operatively by ultrasound to enable prediction of rotator cuff repairability. Tears were classified following ultrasound as repairable or irreparable, and were correlated with intra-operative repairability. Results Ultrasound assessment of rotator cuff tear repairability has a sensitivity of 86% (p rotator cuff repairability were tear size (p rotator cuff tear. Conclusions Ultrasound assessment is accurate in predicting rotator cuff tear repairability. Tear size or anteroposterior tear length and age were the best predictors of repairability. PMID:27582996

  15. The surface science of enzymes

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Nørskov, Jens Kehlet

    2002-01-01

    One of the largest challenges to science in the coming years is to find the relation between enzyme structure and function. Can we predict which reactions an enzyme catalyzes from knowledge of its structure-or from its amino acid sequence? Can we use that knowledge to modify enzyme function......? To solve these problems we must understand in some detail how enzymes interact with reactants from its surroundings. These interactions take place at the surface of the enzyme and the question of enzyme function can be viewed as the surface science of enzymes. In this article we discuss how to describe...... catalysis by enzymes, and in particular the analogies between enzyme catalyzed reactions and surface catalyzed reactions. We do this by discussing two concrete examples of reactions catalyzed both in nature (by enzymes) and in industrial reactors (by inorganic materials), and show that although analogies...

  16. Amperometric Enzyme Electrodes

    Science.gov (United States)

    1989-12-01

    form of carbon (glascy carbon, graphite, reticulated vitreous carbon, carbon paste, fiber or foil). Carbon is favored for enzyme immoblization...interference from spurious electroactive species in blood, t proprietary multilayer membranie that includes a cellulose acetate memirane and a Nucleopore

  17. ISFET based enzyme sensors

    NARCIS (Netherlands)

    van der Schoot, Bart H.; Bergveld, Piet

    1987-01-01

    This paper reviews the results that have been reported on ISFET based enzyme sensors. The most important improvement that results from the application of ISFETs instead of glass membrane electrodes is in the method of fabrication. Problems with regard to the pH dependence of the response and the

  18. Polymorphisms in human DNA repair genes and head and neck squamous cell carcinoma

    Indian Academy of Sciences (India)

    Rim Khlifi; Ahmed Rebai; Amel Hamza-Chaffai

    2012-12-01

    Genetic polymorphisms in some DNA repair proteins are associated with a number of malignant transformations like head and neck squamous cell carcinoma (HNSCC). Xeroderma pigmentosum group D (XPD) and X-ray repair cross-complementing proteins 1 (XRCC1) and 3 (XRCC3) genes are involved in DNA repair and were found to be associated with HNSCC in numerous studies. To establish our overall understanding of possible relationships between DNA repair gene polymorphisms and development of HNSCC, we surveyed the literature on epidemiological studies that assessed potential associations with HNSCC risk in terms of gene–environment interactions, genotype-induced functional defects in enzyme activity and/or protein expression, and the influence of ethnic origin on these associations.We conclude that large, well-designed studies of common polymorphisms in DNA repair genes are needed. Such studies may benefit from analysis of multiple genes or polymorphisms and from the consideration of relevant exposures that may influence the likelihood of HNSCC when DNA repair capacity is reduced.

  19. Photodynamic DNA damage induced by phycocyanin and its repair in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    M. Pádula

    1999-09-01

    Full Text Available In the present study, we analyzed DNA damage induced by phycocyanin (PHY in the presence of visible light (VL using a set of repair endonucleases purified from Escherichia coli. We demonstrated that the profile of DNA damage induced by PHY is clearly different from that induced by molecules that exert deleterious effects on DNA involving solely singlet oxygen as reactive species. Most of PHY-induced lesions are single strand breaks and, to a lesser extent, base oxidized sites, which are recognized by Nth, Nfo and Fpg enzymes. High pressure liquid chromatography coupled to electrochemical detection revealed that PHY photosensitization did not induce 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo at detectable levels. DNA repair after PHY photosensitization was also investigated. Plasmid DNA damaged by PHY photosensitization was used to transform a series of Saccharomyces cerevisiae DNA repair mutants. The results revealed that plasmid survival was greatly reduced in rad14 mutants, while the ogg1 mutation did not modify the plasmid survival when compared to that in the wild type. Furthermore, plasmid survival in the ogg1 rad14 double mutant was not different from that in the rad14 single mutant. The results reported here indicate that lethal lesions induced by PHY plus VL are repaired differently by prokaryotic and eukaryotic cells. Morever, nucleotide excision repair seems to play a major role in the recognition and repair of these lesions in Saccharomyces cerevisiae.

  20. Minimally disruptive schedule repair for MCM missions

    Science.gov (United States)

    Molineaux, Matthew; Auslander, Bryan; Moore, Philip G.; Gupta, Kalyan M.

    2015-05-01

    Mine countermeasures (MCM) missions entail planning and operations in very dynamic and uncertain operating environments, which pose considerable risk to personnel and equipment. Frequent schedule repairs are needed that consider the latest operating conditions to keep mission on target. Presently no decision support tools are available for the challenging task of MCM mission rescheduling. To address this capability gap, we have developed the CARPE system to assist operation planners. CARPE constantly monitors the operational environment for changes and recommends alternative repaired schedules in response. It includes a novel schedule repair algorithm called Case-Based Local Schedule Repair (CLOSR) that automatically repairs broken schedules while satisfying the requirement of minimal operational disruption. It uses a case-based approach to represent repair strategies and apply them to new situations. Evaluation of CLOSR on simulated MCM operations demonstrates the effectiveness of case-based strategy. Schedule repairs are generated rapidly, ensure the elimination of all mines, and achieve required levels of clearance.

  1. Computational enzyme design

    Science.gov (United States)

    Bolon, Daniel N.

    2002-08-01

    The long-term objective of computational enzyme design is the ability to generate efficient protein catalysts for any chemical reaction. This thesis develops and experimentally validates a general computational approach for the design of enzymes with novel function. In order to include catalytic mechanism in protein design, a high-energy state (HES) rotamer (side chain representation) was constructed. In this rotamer, substrate atoms are in a HES. In addition, at least one amino acid side chain is positioned to interact favorably with substrate atoms in their HES and facilitate the reaction. Including an amino acid side chain in the HES rotamer automatically positions substrate relative to a protein scaffold and allows protein design algorithms to search for sequences capable of interacting favorably with the substrate. Because chemical similarity exists between the transition state and the high-energy state, optimizing the protein sequence to interact favorably with the HES rotamer should lead to transition state stabilization. In addition, the HES rotamer model focuses the subsequent computational active site design on a relevant phase space where an amino acid is capable of interacting in a catalytically active geometry with substrate. Using a HES rotamer model of the histidine mediated nucleophilic hydrolysis of p-nitrophenyl acetate, the catalytically inert 108 residue E. coli thioredoxin as a scaffold, and the ORBIT protein design software to compute sequences, an active site scan identified two promising active site designs. Experimentally, both candidate ?protozymes? demonstrated catalytic activity significantly above background. In addition, the rate enhancement of one of these ?protozymes? was the same order of magnitude as the first catalytic antibodies. Because polar groups are frequently buried at enzyme-substrate interfaces, improved modeling of buried polar interactions may benefit enzyme design. By studying native protein structures, rules have been

  2. Quality of life following successful repair of vesicovaginal fistula in Nigeria.

    Science.gov (United States)

    Umoiyoho, Aniefiok J; Inyang-Etoh, Emmanuel C; Abah, Gabriel M; Abasiattai, Aniekan M; Akaiso, Okon E

    2011-01-01

    The impact of obstetric vesicovaginal fistula (VVF), which continues to occur among women in developing countries, can severely affect the health of the women while the condition persists. This study was designed to discover the effect of successful VVF repair on affected women's quality of life. A comparison of the quality of life of a cross-section of women who had VVF was carried out before and 6 months after successful repair. Quality of life was assessed using the WHO Quality of Life (WHOQOL)-BREF Questionnaire. Of the 150 women studied, only 20% felt satisfied with their general state of health and quality of life before the repair, while this increased to 90% following successful repair (highly statistically significant at p<0.000). In the physical health domain, the mean quality of life score was 67.9 ± 4.4 before and 69.3 ± 3.4 after successful repair (p<0.01). In the mental health domain, the mean quality of life score was 32.4 ± 8.7 before and 74.7 ± 3.2 after successful repair (p<0.005). In the social health domain, the mean score was 20.2 ± 2.7 before and 69.7 ± 2.3 after successful repair (p<0.001). In the environment domain, the mean score of quality of life was 60.3 ± 4.3 before repair and 59.7 ± 2.7 after successful repair (comparable at p<0.2). Successful repair of VVF is associated with significant improvement in the multidimensional quality of life among affected women.

  3. EnzymeDetector: an integrated enzyme function prediction tool and database

    Directory of Open Access Journals (Sweden)

    Schomburg Dietmar

    2011-09-01

    Full Text Available Abstract Background The ability to accurately predict enzymatic functions is an essential prerequisite for the interpretation of cellular functions, and the reconstruction and analysis of metabolic models. Several biological databases exist that provide such information. However, in many cases these databases provide partly different and inconsistent genome annotations. Description We analysed nine prokaryotic genomes and found about 70% inconsistencies in the enzyme predictions of the main annotation resources. Therefore, we implemented the annotation pipeline EnzymeDetector. This tool automatically compares and evaluates the assigned enzyme functions from the main annotation databases and supplements them with its own function prediction. This is based on a sequence similarity analysis, on manually created organism-specific enzyme information from BRENDA (Braunschweig Enzyme Database, and on sequence pattern searches. Conclusions EnzymeDetector provides a fast and comprehensive overview of the available enzyme function annotations for a genome of interest. The web interface allows the user to work with customisable weighting schemes and cut-offs for the different prediction methods. These customised quality criteria can easily be applied, and the resulting annotation can be downloaded. The summarised view of all used annotation sources provides up-to-date information. Annotation errors that occur in only one of the databases can be recognised (because of their low relevance score. The results are stored in a database and can be accessed at http://enzymedetector.tu-bs.de.

  4. Honey, I Shrunk the DNA : DNA Length as a Probe for Nucleic-Acid Enzyme Activity

    NARCIS (Netherlands)

    Oijen, Antoine M. van

    2007-01-01

    The replication, recombination, and repair of DNA are processes essential for the maintenance of genomic information and require the activity of numerous enzymes that catalyze the polymerization or digestion of DNA. This review will discuss how differences in elastic properties between single- and d

  5. Honey, I Shrunk the DNA : DNA Length as a Probe for Nucleic-Acid Enzyme Activity

    NARCIS (Netherlands)

    Oijen, Antoine M. van

    2007-01-01

    The replication, recombination, and repair of DNA are processes essential for the maintenance of genomic information and require the activity of numerous enzymes that catalyze the polymerization or digestion of DNA. This review will discuss how differences in elastic properties between single- and d

  6. Phosphorylation of linker histones regulates ATP-dependent chromatin remodeling enzymes.

    NARCIS (Netherlands)

    Horn, P.J.; Carruthers, L.M.; Logie, C.; Hill, D.A.; Solomon, M.J.; Wade, P.A.; Imbalzano, A.N.; Hansen, J.; Peterson, C.L.

    2002-01-01

    Members of the ATP-dependent family of chromatin remodeling enzymes play key roles in the regulation of transcription, development, DNA repair and cell cycle control. We find that the remodeling activities of the ySWI/SNF, hSWI/SNF, xMi-2 and xACF complexes are nearly abolished by incorporation of l

  7. Unscheduled DNA synthesis in xeroderma pigmentosum cells after microinjection of yeast photoreactivating enzyme.

    NARCIS (Netherlands)

    J.C.M. Zwetsloot; J.H.J. Hoeijmakers (Jan); W. Vermeulen (Wim); A.P.M. Eker (André); D. Bootsma (Dirk)

    1986-01-01

    textabstractPhotoreactivating enzyme (PRE) from yeast causes a light-dependent reduction of UV-induced unscheduled DNA synthesis (UDS) when injected into the cytoplasm of repair-proficieint human fibroblasts (Zwetsloot et al., 1985). This result indicates that the exogenous PRE monomerizers UV-induc

  8. The Moderately Efficient Enzyme: Futile Encounters and Enzyme Floppiness.

    Science.gov (United States)

    Bar-Even, Arren; Milo, Ron; Noor, Elad; Tawfik, Dan S

    2015-08-18

    The pioneering model of Henri, Michaelis, and Menten was based on the fast equilibrium assumption: the substrate binds its enzyme reversibly, and substrate dissociation is much faster than product formation. Here, we examine this assumption from a somewhat different point of view, asking what fraction of enzyme-substrate complexes are futile, i.e., result in dissociation rather than product formation. In Knowles' notion of a "perfect" enzyme, all encounters of the enzyme with its substrate result in conversion to product. Thus, the perfect enzyme's catalytic efficiency, kcat/KM, is constrained by only the diffusion on-rate, and the fraction of futile encounters (defined as φ) approaches zero. The available data on >1000 different enzymes suggest that for ≥90% of enzymes φ > 0.99 and for the "average enzyme" φ ≥ 0.9999; namely, <1 of 10(4) encounters is productive. Thus, the "fast equilibrium" assumption holds for the vast majority of enzymes. We discuss possible molecular origins for the dominance of futile encounters, including the coexistence of multiple sub-states of an enzyme's active site (enzyme floppiness) and/or its substrate. Floppiness relates to the inherent flexibility of proteins, but also to conflicting demands, or trade-offs, between rate acceleration (the rate-determining chemical step) and catalytic turnover, or between turnover rate and accuracy. The study of futile encounters and active-site floppiness may contribute to a better understanding of enzyme catalysis, enzyme evolution, and improved enzyme design.

  9. Methods of repairing a substrate

    Science.gov (United States)

    Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

    2011-01-01

    A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium boride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

  10. CHRONIC PAIN AFTER INGUINAL HERNIA REPAIR

    Directory of Open Access Journals (Sweden)

    Suresh

    2014-09-01

    Full Text Available : BACKGROUND: Chronic post herniorrhaphy groin pain is defined as pain lasting > 6 months after surgery, which is one of the most important complication occurring after inguinal hernia repair, occurs with greater frequency than previously thought. Chronic groin pain is one of the most significant complications following inguinal hernia repair, and majority of chronic pain has been attributed to ilioinguinal nerve entrapment. Various other factors are involved in development of chronic pain. MATERIAL AND METHODS: Patients undergoing elective inguinal hernioplasty in Victoria hospital from November2011 to May 2013 were included in the study. A total of 227 patients met the inclusion criteria and were available for follow up at end of six months. A detailed preoperative, intraoperative and post-operative details of cases were recorded according to proforma. The postoperative pain and pain at two, seven days and at end of six months were recorded on a VAS scale. RESULTS: Chronic pain at six month follow up was present in 89 patients constituting 39.4% of all patients undergoing hernia repair. It was seen that 26.9% without preoperative pain developed chronic pain whereas 76.7 % of patients with preoperative pain developed chronic pain. Patients with significant preoperative pain had higher chances of developing chronic pain (p<.0001. Preemptive analgesia failed to show statistical significance in development of chronic pain (p=0.079. Nerve injury were present in 22 of cases it was found that nerve injury significantly affected development of chronic pain (p=0.001.Post-operative infiltration of local anesthesia was practiced in 16.3 % of cases and it was found that local infiltration at incision site significantly reduced incidence of chronic pain (p=0.001.Postoperative complications in the form of hematoma, seroma or infection was present in 8.5 % of cases. It was found that post-operative complication not only increased early post-operative pain

  11. Large Extremity Peripheral Nerve Repair

    Science.gov (United States)

    2015-10-01

    IL, Kochevar IE, Redmond RW. Large extremity peripheral nerve repair. Military Health System Research Symposium (MHSRS) Fort Lauderdale, FL. August...some notable discoveries that may impact military health care in the near future. There is a clear need in military medicine to improve outcomes in...membranes or “caul” intact was considered extremely lucky. Children were gifted with life-long happiness , the ability to see spirits, and protection

  12. Shelf Stable Epoxy Repair Adhesive

    Science.gov (United States)

    2015-02-01

    manufacturing operations are more efficient , discarding less expired film. Commercial and military aircraft repair operations at Boeing experience very similar...successfully encapsulated at concentrations greater than 50 wt% within four N N = CC Infoscitex Corporation Shelf Stable Epoxy Resin Adhesive WP-1763 8...affects the composition of the encapsulant , which in turn affects the ability of the encapsulant to wet the core phase, the barrier properties of the

  13. Pain after groin hernia repair

    DEFF Research Database (Denmark)

    Callesen, T; Bech, K; Nielsen, R

    1998-01-01

    BACKGROUND: The purpose of the study was to provide a detailed description of postoperative pain after elective day-case open inguinal hernia repair under local anaesthesia. METHODS: This was a prospective consecutive case series study. After 500 hernia operations in 466 unselected patients aged 18...... between types of surgery or hernia. CONCLUSION: Pain remained a problem despite the pre-emptive use of opioids, non-steroidal anti-inflammatory drugs and local anaesthesia, irrespective of surgical technique....

  14. Biologics for tendon repair

    OpenAIRE

    2014-01-01

    Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic options used to repair ruptured tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored tendons do not recover their complete strength and functionality. Unfortunately,...

  15. Large Extremity Peripheral Nerve Repair

    Science.gov (United States)

    2016-12-01

    71. Burman S, Tejwani S, Vemuganti GK. Ophthalmic applications of preserved human amniotic membrane: a review of current indications. Cell Tissue Bank...segmental nerve deficit repair using isograft show the best performing wrap/ fixation method to be sutureless photochemical tissue bonding with the...crosslinked amnion wrap. Autograft is often unavailable in wounded warriors, due to extensive tissue damage and amputation and, importantly, we also

  16. Eukaryotic nucleotide excision repair: from understanding mechanisms to influencing biology

    Institute of Scientific and Technical Information of China (English)

    Sarah C Shuck; Emily A Short; John J Turchi

    2008-01-01

    Repair of bulky DNA adducts by the nucleotide excision repair (NER) pathway is one of the more versatile DNA repair pathways for the removal of DNA lesions. There are two subsets of the NER pathway, global genomic-NER (GG-NER) and transcription-coupled NER (TC-NER), which differ only in the step involving recognition of the DNA lesion. Following recognition of the damage, the sub-pathways then converge for the incision/excision steps and subsequent gap filling and ligation steps. This review will focus on the GGR sub-pathway of NER while the TCR sub-pathway will be covered in another article in this issue. The ability of the NER pathway to repair a wide array of adducts stems, in part, from the mechanisms involved in the initial recognition step of the damaged DNA and results in NER impacting an equally wide array of human physiological responses and events. In this review, the impact of NER on carcinogenesis, neurological function, sensitivity to environmental factors and sensitivity to cancer therapeutics will be discussed. The knowledge generated in our understanding of the NER pathway over the past 40 years has resulted from advances in the fields of animal model systems, mammalian genetics and in vitro biochemistry, as well as from reconstitution studies and structural analyses of the proteins and enzymes that participate in this pathway. Each of these avenues of research has contributed significantly to our understanding of how the NER pathway works and how alterations in NER activity, both positive and negative, influence human biology.

  17. Revisional laparoscopic parastomal hernia repair.

    Science.gov (United States)

    Zacharakis, Emmanouil; Shalhoub, Joseph; Selvapatt, Nowlan; Darzi, Ara; Ziprin, Paul

    2008-01-01

    We herein report a laparoscopically performed re-do operation on a patient who had previously undergone a laparoscopic parastomal hernia repair. We describe the case of a 71-year-old patient who presented within 3 months of her primary laparoscopic parastomal hernia repair with recurrence. On relaparoscopy, dense adhesions to the mesh were found, and the mesh had migrated into the hernia sac. This had allowed loops of small bowel to herniate into the sac. The initial part of the procedure involved the lysis of adhesions. A piece of Gore-Tex DualMesh with a central keyhole and a radial slit was cut so that it could provide at least 3 cm to 5 cm of overlap of the fascial defect. The tails of the mesh were wrapped around the bowel, and the mesh was secured to the margins of the hernia with circumferential metal tacking and 4 transfascial sutures. The patient remains in satisfactory condition and no recurrence or any surgery-related problem has been observed during 8 months of follow-up. Revisional laparoscopic repair of parastomal hernias seems feasible and has been shown to be safe and effective in this case. The success of this approach depends on longer follow-up reports and standardization of the technical elements.

  18. Information Needs While A Disaster Is Occurring

    Science.gov (United States)

    Perry, S. C.

    2010-12-01

    that rainfall intensity at their homes might be less than the intensity up in the mountains where the debris flows would start. Nor did they know that debris flows travel too quickly to be outrun. These and many other examples indicate need for social and natural scientists to increase awareness of what to expect when the disaster strikes. This information must be solidly understood before the event occurs - while a disaster is unfolding there are no teachable moments. Case studies indicate that even those who come into a disaster well educated about the phenomenon can struggle to apply what they know when the real situation is at hand. In addition, psychological studies confirm diminished ability to comprehend information at times of stress.

  19. Comparing Biomechanical Properties, Repair Times, and Value of Common Core Flexor Tendon Repairs.

    Science.gov (United States)

    Chauhan, Aakash; Schimoler, Patrick; Miller, Mark C; Kharlamov, Alexander; Merrell, Gregory A; Palmer, Bradley A

    2017-04-01

    The aim of the study was to compare biomechanical strength, repair times, and repair values for zone II core flexor tendon repairs. A total of 75 fresh-frozen human cadaveric flexor tendons were harvested from the index through small finger and randomized into one of 5 repair groups: 4-stranded cross-stitch cruciate (4-0 polyester and 4-0 braided suture), 4-stranded double Pennington (2-0 knotless barbed suture), 4-stranded Pennington (4-0 double-stranded braided suture), and 6-stranded modified Lim-Tsai (4-0 looped braided suture). Repairs were measured in situ and their repair times were measured. Tendons were linearly loaded to failure and multiple biomechanical values were measured. The repair value was calculated based on operating room costs, repair times, and suture costs. Analysis of variance (ANOVA) and Tukey post hoc statistical analysis were used to compare repair data. The braided cruciate was the strongest repair ( P > .05) but the slowest ( P > .05), and the 4-stranded Pennington using double-stranded suture was the fastest ( P > .05) to perform. The total repair value was the highest for braided cruciate ( P > .05) compared with all other repairs. Barbed suture did not outperform any repairs in any categories. The braided cruciate was the strongest of the tested flexor tendon repairs. The 2-mm gapping and maximum load to failure for this repair approached similar historical strength of other 6- and 8-stranded repairs. In this study, suture cost was negligible in the overall repair cost and should be not a determining factor in choosing a repair.

  20. Mechanistic insights into type III restriction enzymes.

    Science.gov (United States)

    Raghavendra, Nidhanapati K; Bheemanaik, Shivakumara; Rao, Desirazu N

    2012-01-01

    Type III restriction-modification (R-M) enzymes need to interact with two separate unmethylated DNA sequences in indirectly repeated, head-to-head orientations for efficient cleavage to occur at a defined location next to only one of the two sites. However, cleavage of sites that are not in head-to-head orientation have been observed to occur under certain reaction conditions in vitro. ATP hydrolysis is required for the long-distance communication between the sites prior to cleavage. Type III R-M enzymes comprise two subunits, Res and Mod that form a homodimeric Mod2 and a heterotetrameric Res2Mod2 complex. The Mod subunit in M2 or R2M2 complex recognizes and methylates DNA while the Res subunit in R2M2 complex is responsible for ATP hydrolysis, DNA translocation and cleavage. A vast majority of biochemical studies on Type III R-M enzymes have been undertaken using two closely related enzymes, EcoP1I and EcoP15I. Divergent opinions about how the long-distance interaction between the recognition sites exist and at least three mechanistic models based on 1D- diffusion and/or 3D- DNA looping have been proposed.

  1. Programmable DNA-Guided Artificial Restriction Enzymes.

    Science.gov (United States)

    Enghiad, Behnam; Zhao, Huimin

    2017-02-06

    Restriction enzymes are essential tools for recombinant DNA technology that have revolutionized modern biological research. However, they have limited sequence specificity and availability. Here we report a Pyrococcus furiosus Argonaute (PfAgo) based platform for generating artificial restriction enzymes (AREs) capable of recognizing and cleaving DNA sequences at virtually any arbitrary site and generating defined sticky ends of varying length. Short DNA guides are used to direct PfAgo to target sites for cleavage at high temperatures (>87 °C) followed by reannealing of the cleaved single stranded DNAs. We used this platform to generate over 18 AREs for DNA fingerprinting and molecular cloning of PCR-amplified or genomic DNAs. These AREs work as efficiently as their naturally occurring counterparts, and some of them even do not have any naturally occurring counterparts, demonstrating easy programmability, generality, versatility, and high efficiency for this new technology.

  2. Contact models of repaired articular surfaces: influence of loading conditions and the superficial tangential zone.

    Science.gov (United States)

    Owen, John R; Wayne, Jennifer S

    2011-07-01

    The superficial tangential zone (STZ) plays a significant role in normal articular cartilage's ability to support loads and retain fluids. To date, tissue engineering efforts have not replicated normal STZ function in cartilage repairs. This finite element study examined the STZ's role in normal and repaired articular surfaces under different contact conditions. Contact area and pressure distributions were allowed to change with time, tension-compression nonlinearity modeled collagen behavior in the STZ, and nonlinear geometry was incorporated to accommodate finite deformation. Responses to loading via impermeable and permeable rigid surfaces were compared to loading via normal cartilage, a more physiologic condition, anticipating the two rigid loading surfaces would bracket that of normal. For models loaded by normal cartilage, an STZ placed over the inferior repair region reduced the short-term axial compression of the articular surface by 15%, when compared to a repair without an STZ. Covering the repair with a normal STZ shifted the flow patterns and strain levels back toward that of normal cartilage. Additionally, reductions in von Mises stress (21%) and an increase in fluid pressure (13%) occurred in repair tissue under the STZ. This continues to show that STZ properties of sufficient quality are likely critical for the survival of transplanted constructs in vivo. However, response to loading via normal cartilage did not always fall within ranges predicted by the rigid surfaces. Use of more physiologic contact models is recommended for more accurate investigations into properties critical to the success of repair tissues.

  3. Multiple-pathway analysis of double-strand break repair mutations in Drosophila.

    Directory of Open Access Journals (Sweden)

    Dena M Johnson-Schlitz

    2007-04-01

    Full Text Available The analysis of double-strand break (DSB repair is complicated by the existence of several pathways utilizing a large number of genes. Moreover, many of these genes have been shown to have multiple roles in DSB repair. To address this complexity we used a repair reporter construct designed to measure multiple repair outcomes simultaneously. This approach provides estimates of the relative usage of several DSB repair pathways in the premeiotic male germline of Drosophila. We applied this system to mutations at each of 11 repair loci plus various double mutants and altered dosage genotypes. Most of the mutants were found to suppress one of the pathways with a compensating increase in one or more of the others. Perhaps surprisingly, none of the single mutants suppressed more than one pathway, but they varied widely in how the suppression was compensated. We found several cases in which two or more loci were similar in which pathway was suppressed while differing in how this suppression was compensated. Taken as a whole, the data suggest that the choice of which repair pathway is used for a given DSB occurs by a two-stage "decision circuit" in which the DSB is first placed into one of two pools from which a specific pathway is then selected.

  4. High-Throughput Microplate-Based Assay to Monitor Plasma Membrane Wounding and Repair

    Directory of Open Access Journals (Sweden)

    Sarika Pathak-Sharma

    2017-07-01

    Full Text Available The plasma membrane of mammalian cells is susceptible to disruption by mechanical and biochemical damages that frequently occur within tissues. Therefore, efficient and rapid repair of the plasma membrane is essential for maintaining cellular homeostasis and survival. Excessive damage of the plasma membrane and defects in its repair are associated with pathological conditions such as infections, muscular dystrophy, heart failure, diabetes, and lung and neurodegenerative diseases. The molecular events that remodel the plasma membrane during its repair remain poorly understood. In the present work, we report the development of a quantitative high-throughput assay that monitors the efficiency of the plasma membrane repair in real time using a sensitive microplate reader. In this assay, the plasma membrane of living cells is perforated by the bacterial pore-forming toxin listeriolysin O and the integrity and recovery of the membrane are monitored at 37°C by measuring the fluorescence intensity of the membrane impermeant dye propidium iodide. We demonstrate that listeriolysin O causes dose-dependent plasma membrane wounding and activation of the cell repair machinery. This assay was successfully applied to cell types from different origins including epithelial and muscle cells. In conclusion, this high-throughput assay provides a novel opportunity for the discovery of membrane repair effectors and the development of new therapeutic compounds that could target membrane repair in various pathological processes, from degenerative to infectious diseases.

  5. Fabrication Flaw Density and Distribution In Repairs to Reactor Pressure Vessel and Piping Welds

    Energy Technology Data Exchange (ETDEWEB)

    GJ Schuster, FA Simonen, SR Doctor

    2008-04-01

    The Pacific Northwest National Laboratory is developing a generalized fabrication flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in U.S. operating reactors. The purpose of the generalized flaw distribution is to predict component-specific flaw densities. The estimates of fabrication flaws are intended for use in fracture mechanics structural integrity assessments. Structural integrity assessments, such as estimating the frequency of loss-of-coolant accidents, are performed by computer codes that require, as input, accurate estimates of flaw densities. Welds from four different reactor pressure vessels and a collection of archived pipes have been studied to develop empirical estimates of fabrication flaw densities. This report describes the fabrication flaw distribution and characterization in the repair weld metal of vessels and piping. This work indicates that large flaws occur in these repairs. These results show that repair flaws are complex in composition and sometimes include cracks on the ends of the repair cavities. Parametric analysis using an exponential fit is performed on the data. The relevance of construction records is established for describing fabrication processes and product forms. An analysis of these records shows there was a significant change in repair frequency over the years when these components were fabricated. A description of repair flaw morphology is provided with a discussion of fracture mechanics significance. Fabrication flaws in repairs are characterized using optimized-access, high-sensitivity nondestructive ultrasonic testing. Flaw characterizations are then validated by other nondestructive evaluation techniques and complemented by destructive testing.

  6. Effect of timing of surgical SSP tendon repair on muscle alterations.

    Science.gov (United States)

    Uhthoff, Hans K; Coletta, Elizabeth; Trudel, Guy

    2014-11-01

    To investigate the impacts of delayed repairs of a supraspinatus tendon tear on the supraspinatus muscle, we used an animal model data from two previously published studies in which one supraspinatus (SSP) tendon was detached. In one cohort, the rabbits were killed in groups of 10 at 4, 8, and 12 weeks. In the other cohort, a repair was done at these time points, 12 rabbits each, and the animals killed were 12 weeks later. SSP fossa volume (Muscle belly plus extramuscular fat [e-fat] volume), percentage of intramuscular fat (i-fat), and muscle tissue volume (muscle belly volume minus i-fat), as well as CT determination of e-fat and i-fat of both cohorts, were compared. Fossa volume increased (p Muscle belly and muscle tissue volumes did not increase after repair (p > 0.05), but early repair prevented further volume losses, a fact not seen after 8 and 12 weeks delay of repair. No reversal of e-fat or of i-fat occurred, in fact i-fat almost doubled after 4 weeks delay of repair (p fat results. We conclude that early repair prevented loss of muscle belly and muscle tissue volumes, but that it has no positive influence on fat accumulation. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  7. DNA repair in Haemophilus influenzae: isolation and characterization of an ultraviolet sensitive mutator mutant

    Energy Technology Data Exchange (ETDEWEB)

    Walter, R.B.

    1985-01-01

    DNA repair in Haemophilus influenzae appears to be quite different from that seen in Escherichia coli in that H. influenzae shows neither SOS nor adaptation phenomena. Repair of DNA lesions in H. influenzae has been seen to occur via recombinational, excision, and mismatch repair pathways acting independently of one another. The author has isolated an ultraviolet (UV)-sensitive mutator mutant (mutB1) of H. influenzae Rd which shows deficiencies in both recombinational and mismatch repair pathways. This mutant is sensitive to a variety of DNA damaging agents as well as being hypermutable by alkylating agents and base analogues. MutB1 cells do not show post-UV DNA breakdown but do begin excision after UV irradiation. Genetic transformation with UV-irradiated DNA on mut B1 recipients shows that high (HE) and low (LE) efficiency markers are transformed at a ratio of 1.0 as in the mismatch repair deficient hex 1 mutant; however, kinetics of UV-inactivation experiments indicate that HE markers are sensitized and act as LE markers do on wild type recipients. Thus, the mutB gene product appears to play a role in both DNA repair and genetic transformation. A model is outlined which presents a role for a DNA helicase in both DNA repair and genetic transformation of H. influenzae.

  8. Bond strength of repaired amalgam restorations.

    Science.gov (United States)

    Rey, Rosalia; Mondragon, Eduardo; Shen, Chiayi

    2015-01-01

    This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam. Repaired specimens were stored in artificial saliva for 1, 10, 30, 120, or 360 days before being loaded to failure in a 3-point bending test. Statistical analysis showed significant changes in median FS over time in groups 2 and 4. The effect of the repair method on the FS values after each storage period was significant for most groups except the 30-day storage groups. Amalgam-amalgam repair with adequate condensation yielded the most consistent and durable bond. An amalgam bonding agent could be beneficial when firm condensation on the repair surface cannot be achieved or when tooth structure is involved. Composite resin can be a viable option for amalgam repair in an esthetically demanding region, but proper mechanical modification of the amalgam surface and selection of the proper bonding system are essential.

  9. Treatment and Controversies in Paraesophageal Hernia Repair

    Directory of Open Access Journals (Sweden)

    P. Marco eFisichella

    2015-04-01

    Full Text Available Background: Historically all paraesophageal hernias were repaired surgically, today intervention is reserved for symptomatic paraesophageal hernias. In this review, we describe the indications for repair and explore the controversies in paraesophageal hernia repair, which include a comparison of open to laparoscopic paraesophageal hernia repair, the necessity of complete sac excision, the routine performance of fundoplication, and the use of mesh for hernia repair.Methods: We searched Pubmed for papers published between 1980 and 2015 using the following keywords: hiatal hernias, paraesophageal hernias, regurgitation, dysphagia, gastroesophageal reflux disease, aspiration, GERD, endoscopy, manometry, pH monitoring, proton pump inhibitors, anemia, iron deficiency anemia, Nissen fundoplication, sac excision, mesh, mesh repair. Results: Indications for paraesophageal hernia repair have changed, and currently symptomatic paraesophageal hernias are recommended for repair. In addition, it is important not to overlook iron-deficiency anemia and pulmonary complaints, which tend to improve with repair. Current practice favors a laparoscopic approach, complete sac excision, primary crural repair with or without use of mesh, and a routine fundoplication.

  10. Halophilic adaptation of enzymes.

    Science.gov (United States)

    Madern, D; Ebel, C; Zaccai, G

    2000-04-01

    It is now clear that the understanding of halophilic adaptation at a molecular level requires a strategy of complementary experiments, combining molecular biology, biochemistry, and cellular approaches with physical chemistry and thermodynamics. In this review, after a discussion of the definition and composition of halophilic enzymes, the effects of salt on their activity, solubility, and stability are reviewed. We then describe how thermodynamic observations, such as parameters pertaining to solvent-protein interactions or enzyme-unfolding kinetics, depend strongly on solvent composition and reveal the important role played by water and ion binding to halophilic proteins. The three high-resolution crystal structures now available for halophilic proteins are analyzed in terms of haloadaptation, and finally cellular response to salt stress is discussed briefly.

  11. Immobilized enzymes in organic synthesis.

    Science.gov (United States)

    Mosbach, K

    1985-01-01

    The immobilization of enzymes and cells by different methods and the possible stabilization of immobilized preparations are discussed. An outlook on 'second generation enzyme technology', which involves immobilized multi-enzyme systems and coenzymes, is given with examples: the immobilization of dehydrogenases with their active sites facing one another, and systems containing NAD(H) coenzymes immobilized by coupling to dextran (in an enzyme electrode), to polyethylene glycol (in a membrane reactor), or to enzymes themselves. The use of immobilized enzymes to synthesize peptides and disaccharides is described.

  12. Repair grinding -- An alternative to ultrasonic rejection for oilfield tubes

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, R.K. (NDE Information Consultants, Houston, TX (United States))

    1994-10-01

    The price of scrap steel rose from $95 to $140/ton in 1993, making tubular production costs higher and making internal repair grinding of oil field tubes with minor internal surface breaking imperfections an extremely cost effective method for placing potentially reject tubulars back into service. Such imperfections often occur and are presently sized by the shear wave ultrasonic amplitude method. This article is written to illustrate how effective repair grinding can be in producing prime material within the API specifications 5CT, specification for Casing and Tubing; 5D, Specification for Drill Pipe; and 5L, Line Pipe. Ninety percent of high grade and 50--60% of midgrade materials can be saved by this method.

  13. [Horizontal root fracture repaired by cementum--a case report].

    Science.gov (United States)

    Lin, K R; Kuo, J S

    1989-09-20

    Horizontal root fractures are rare among dental trauma. According to Dr. Andreasen's report there are four types of repairs after root fractures. They are 1. healing with calcified tissue; 2. interposition of connective tissue; 3. interposition of connective and bony tissue; 4. interposition of granulation tissue. This report presented a case of horizontal root fracture in a 27 years old female patient. The patient had a trauma in the front teeth about 15 years ago. Spontaneous healing occurred without dental treatment at that moment. However, symptoms appeared recently as a dento-alveolar abscess. Radiograph revealed a horizontal fracture at the middle third of the root portion of the left upper central incisor, and irregular hard tissue over the fractured area. Histologically, the main component of repair tissue is cementum.

  14. Hepatocyte growth factor in lung repair and pulmonary fibrosis

    Institute of Scientific and Technical Information of China (English)

    Ronald Allan M PANGANIBAN; Regina M DAY

    2011-01-01

    Pulmonary remodeling is characterized by the permanent and progressive loss of the normal alveolar architecture, especially the loss of alveolar epithelial and endothelial cells, persistent proliferation of activated fibroblasts, or myoflbroblasts, and alteration of extracellular matrix. Hepatocyte growth factor (HGF) is a pleiotropic factor, which induces cellular motility, survival, proliferation, and morphogenesis, depending upon the cell type. In the adult, HGF has been demonstrated to play a critical role in tissue repair, including in the lung. Administration of HGF protein or ectopic expression of HGF has been demonstrated in animal models of pulmonary fibrosis to induce normal tissue repair and to prevent fibrotic remodeling. HGF-induced inhibition of fibrotic remodeling may occur via multiple direct and indirect mechanisms including the induction of cell survival and proliferation of pulmonary epithelial and endothelial cells, and the reduction of myofibroblast accumulation.

  15. An in vitro assay to study the recruitment and substrate specificity of chromatin modifying enzymes

    Directory of Open Access Journals (Sweden)

    Vermeulen Michiel

    2004-01-01

    Full Text Available Post-translational modifications of core histones play an important role in regulating fundamental biological processes such as DNA repair, transcription and replication. In this paper, we describe a novel assay that allows sequential targeting of distinct histone modifying enzymes to immobilized nucleosomal templates using recombinant chimeric targeting molecules. The assay can be used to study the histone substrate specificity of chromatin modifying enzymes as well as whether and how certain enzymes affect each other's histone modifying activities. As such the assay can help to understand how a certain histone code is established and interpreted.

  16. Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions

    Science.gov (United States)

    Allison, S. D.; Jastrow, J. D.

    2004-12-01

    Extracellular enzymes are necessary to degrade complex organic compounds present in soils. Using physical fractionation procedures, we tested whether old soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay fraction, which contains carbon with a mean residence time of ~200 years. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in organic matter fractions than in bulk soil, consistent with the rapid turnover of these fractions. Polyphenol oxidase activity was 3 times greater in the clay fraction than in the bulk soil, despite very slow carbon turnover in this fraction. Changes in enzyme activity across the restoration chronosequence were small once adjusted for increases in soil carbon concentration, although polyphenol oxidase activity per unit carbon declined by 50% in native prairie versus cultivated soil. These results are consistent with a `two-pool' model of enzyme and carbon turnover in grassland soils. In light organic matter fractions, enzyme production and carbon turnover both occur rapidly. However, in mineral-dominated fractions, both enzymes and their carbon substrates are immobilized on mineral surfaces, leading to slow turnover. Soil carbon accumulation in the clay fraction and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular scale, rather than the micron to millimeter scale.

  17. 2'-(R)-Fluorinated mC, hmC, fC and caC triphosphates are substrates for DNA polymerases and TET-enzymes.

    Science.gov (United States)

    Schröder, A S; Parsa, E; Iwan, K; Traube, F R; Wallner, M; Serdjukow, S; Carell, T

    2016-12-13

    A deeper investigation of the chemistry that occurs on the newly discovered epigenetic DNA bases 5-hydroxymethyl-(hmdC), 5-formyl-(fdC), and 5-carboxy-deoxycytidine (cadC) requires chemical tool compounds, which are able to dissect the different potential reaction pathways in cells. Here we report that the 2'-(R)-fluorinated derivatives F-hmdC, F-fdC, and F-cadC, which are resistant to removal by base excision repair, are good substrates for DNA polymerases and TET enzymes. This result shows that the fluorinated compounds are ideal tool substances to investigate potential C-C-bond cleaving reactions in the context of active demethylation.

  18. RNF4 is required for DNA double-strand break repair in vivo

    DEFF Research Database (Denmark)

    Vyas, R; Kumar, R; Clermont, F

    2013-01-01

    for both homologous recombination (HR) and non-homologous end joining repair. To establish a link between Rnf4 and the DNA damage response (DDR) in vivo, we generated an Rnf4 allelic series in mice. We show that Rnf4-deficiency causes persistent ionizing radiation-induced DNA damage and signaling......Unrepaired DNA double-strand breaks (DSBs) cause genetic instability that leads to malignant transformation or cell death. Cells respond to DSBs with the ordered recruitment of signaling and repair proteins to the sites of DNA lesions. Coordinated protein SUMOylation and ubiquitylation have crucial......, and that Rnf4-deficient cells and mice exhibit increased sensitivity to genotoxic stress. Mechanistically, we show that Rnf4 targets SUMOylated MDC1 and SUMOylated BRCA1, and is required for the loading of Rad51, an enzyme required for HR repair, onto sites of DNA damage. Similarly to inactivating mutations...

  19. ppGpp couples transcription to DNA repair in E. coli.

    Science.gov (United States)

    Kamarthapu, Venu; Epshtein, Vitaly; Benjamin, Bradley; Proshkin, Sergey; Mironov, Alexander; Cashel, Michael; Nudler, Evgeny

    2016-05-20

    The small molecule alarmone (p)ppGpp mediates bacterial adaptation to nutrient deprivation by altering the initiation properties of RNA polymerase (RNAP). ppGpp is generated in Escherichia coli by two related enzymes, RelA and SpoT. We show that ppGpp is robustly, but transiently, induced in response to DNA damage and is required for efficient nucleotide excision DNA repair (NER). This explains why relA-spoT-deficient cells are sensitive to diverse genotoxic agents and ultraviolet radiation, whereas ppGpp induction renders them more resistant to such challenges. The mechanism of DNA protection by ppGpp involves promotion of UvrD-mediated RNAP backtracking. By rendering RNAP backtracking-prone, ppGpp couples transcription to DNA repair and prompts transitions between repair and recovery states.

  20. Sharpening the ends for repair: mechanisms and regulation of DNA resection

    Institute of Scientific and Technical Information of China (English)

    Sharad C.Paudyal; Zhongsheng You

    2016-01-01

    DNA end resection is a key process in the cellular response to DNA double-strand break damage that is essential for genome maintenance and cell survival.Resection involves selective processing of 5' ends of broken DNA to generate ssDNA overhangs,which in turn control both DNA repair and checkpoint signaling.DNA resection is the first step in homologous recombination-mediated repair and a prerequisite for the activation of the ataxia telangiectasia mutated and Rad3-related (ATR)-dependent checkpoint that coordinates repair with cell cycle progression and other cellular processes.Resection occurs in a cell cycle-dependent manner and is regulated by multiple factors to ensure an optimal amount of ssDNA required for proper repair and genome stability.Here,we review the latest findings on the molecular mechanisms and regulation of the DNA end resection process and their implications for cancer formation and treatment.

  1. Three-Dimensional Printed Prosthesis for Repair of Superior Canal Dehiscence.

    Science.gov (United States)

    Kozin, Elliott D; Remenschneider, Aaron K; Cheng, Song; Nakajima, Hideko Heidi; Lee, Daniel J

    2015-10-01

    Outcomes following repair of superior canal dehiscence (SCD) are variable, and surgery carries a risk of persistent or recurrent SCD symptoms, as well as a risk of hearing loss and vestibulopathy. Poor outcomes may occur from inadequate repair of the SCD or mechanical insult to the membranous labyrinth. Repair of SCD using a customized, fixed-length prosthesis may address current operative limitations and improve surgical outcomes. We aim to 3-dimensionally print customized prostheses to resurface or occlude bony SCD defects. Dehiscences were created along the arcuate eminence of superior semicircular canals in cadaveric temporal bones. Prostheses were designed and created using computed tomography and a 3-dimensional printer. The prostheses occupied the superior semicircular canal defect, reflected in postrepair computed tomography scans. This novel approach to SCD repair could have advantages over current techniques. Refinement of prosthesis design and materials will be important if this approach is translated into clinical use.

  2. Outpatient repair for inguinal hernia in elderly patients: still a challenge?

    Science.gov (United States)

    Palumbo, Piergaspare; Amatucci, Chiara; Perotti, Bruno; Zullino, Antonio; Dezzi, Claudia; Illuminati, Giulio; Vietri, Francesco

    2014-01-01

    Elective inguinal hernia repair as a day case is a safe and suitable procedure, with well-recognized feasibility. The increasing number of elderly patients requiring inguinal hernia repair leads clinicians to admit a growing number of outpatients. The aim of the current study was to analyze the outcomes (feasibility and safety) of day case treatment in elderly patients. Eighty patients >80 years of age and 80 patients ≤55 years of age underwent elective inguinal hernia repairs under local anesthesia. There were no mortalities or major complications in the elderly undergoing inguinal herniorraphies as outpatients, and only one unanticipated admission occurred in the younger age group. Elective inguinal hernia repair in the elderly has a good outcome, and age alone should not be a drawback to day case treatment. Copyright © 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

  3. A double-ended queue with catastrophes and repairs, and a jump-diffusion approximation

    CERN Document Server

    Di Crescenzo, Antonio; Kumar, Balasubramanian Krishna; Nobile, Amelia G; 10.1007/s11009-011-9214-2

    2011-01-01

    Consider a system performing a continuous-time random walk on the integers, subject to catastrophes occurring at constant rate, and followed by exponentially-distributed repair times. After any repair the system starts anew from state zero. We study both the transient and steady-state probability laws of the stochastic process that describes the state of the system. We then derive a heavy-traffic approximation to the model that yields a jump-diffusion process. The latter is equivalent to a Wiener process subject to randomly occurring jumps, whose probability law is obtained. The goodness of the approximation is finally discussed.

  4. Surgical management of the failed SLAP repair.

    Science.gov (United States)

    Weber, Stephen C

    2010-09-01

    Repair of superior labral tears anterior to posterior (SLAP) lesions has become an increasingly common procedure, despite the low incidence rates reported in the literature. As the incidence of these procedures increases, the surgeons will be increasingly confronted with patients with painful shoulders after SLAP repair. Persistent pain after SLAP repair is multifactorial; careful preoperative workup is necessary to elucidate the cause of pain. Simple failure of the prior SLAP repair will rarely be the cause of persistent pain. Use of tacks is especially worrisome, and suture anchor repair is preferable. Articular cartilage injuries because of either bioabsorbable or metal hardware will often create significant residual disability. Recent literature suggests that older patients may be better served by primary biceps tenodesis rather than SLAP repair.

  5. DNA-Protein Crosslink Proteolysis Repair.

    Science.gov (United States)

    Vaz, Bruno; Popovic, Marta; Ramadan, Kristijan

    2017-06-01

    Proteins that are covalently bound to DNA constitute a specific type of DNA lesion known as DNA-protein crosslinks (DPCs). DPCs represent physical obstacles to the progression of DNA replication. If not repaired, DPCs cause stalling of DNA replication forks that consequently leads to DNA double-strand breaks, the most cytotoxic DNA lesion. Although DPCs are common DNA lesions, the mechanism of DPC repair was unclear until now. Recent work unveiled that DPC repair is orchestrated by proteolysis performed by two distinct metalloproteases, SPARTAN in metazoans and Wss1 in yeast. This review summarizes recent discoveries on two proteases in DNA replication-coupled DPC repair and establishes DPC proteolysis repair as a separate DNA repair pathway for genome stability and protection from accelerated aging and cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Repairing sealing surfaces on aluminum castings

    Science.gov (United States)

    Hanna, T. L.

    1980-01-01

    Approach using stylus nickel plating instead of copper and cadmium plating has simplified repair procedure. Damaged sealing surfaces are stylus nickelplated in one step. Superficial scratches and porous areas are removed more easily from repaired surface by simply lapping sealing areas to required finish. Although method is aimed for aerospace components, it may be easily incorporated into conventional aluminumcasting technology. One-step repair can be considered for cast-aluminum automobile and aircraft engines to reduce time and costs.

  7. Research on Hot Gunning Repairing in Laboratory

    Institute of Scientific and Technical Information of China (English)

    CAO Feng; LONG Shigang; MENG Qingmin; SUN Jialin; HONG Yanruo

    2003-01-01

    The lining of blast furnace may be damaged partly,so that gunning repair is needed. The bonding strength of boundary surface between the repairing layer and remained lining of blast furnace has been studied by thermal simulation.The factors influencing the bonding strength are the ingredient gunning repair temperature,remained lining condition and water content of gunning refractory.The bonding strength decreases with the increases of remained lining temperature.

  8. Role of ubiquitination in meiotic recombination repair

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Programmed and unprogrammed double-strand breaks (DSBs) often arise from such physiological requirements as meiotic recombination, and exogenous insults, such as ionizing radiation (IR). Due to deleterious impacts on genome stability, DSBs must be appropriately processed and repaired in a regulatory manner. Recent investigations have indicated that ubiquitination is a critical factor in DNA damage response and meiotic recombination repair. This review summarizes the effects of proteins and complexes associated with ubiquitination with regard to homologous recombination (HR)-dependent DSB repair.

  9. Loss of transcription factor early growth response gene 1 results in impaired endochondral bone repair.

    Science.gov (United States)

    Reumann, Marie K; Strachna, Olga; Yagerman, Sarah; Torrecilla, Daniel; Kim, Jihye; Doty, Stephen B; Lukashova, Lyudmila; Boskey, Adele L; Mayer-Kuckuk, Philipp

    2011-10-01

    Transcription factors that play a role in ossification during development are expected to participate in postnatal fracture repair since the endochondral bone formation that occurs in embryos is recapitulated during fracture repair. However, inherent differences exist between bone development and fracture repair, including a sudden disruption of tissue integrity followed by an inflammatory response. This raises the possibility that repair-specific transcription factors participate in bone healing. Here, we assessed the consequence of loss of early growth response gene 1 (EGR-1) on endochondral bone healing because this transcription factor has been shown to modulate repair in vascularized tissues. Model fractures were created in ribs of wild type (wt) and EGR-1(-/-) mice. Differences in tissue morphology and composition between these two animal groups were followed over 28 post fracture days (PFDs). In wt mice, bone healing occurred in healing phases characteristic of endochondral bone repair. A similar healing sequence was observed in EGR-1(-/-) mice but was impaired by alterations. A persistent accumulation of fibrin between the disconnected bones was observed on PFD7 and remained pronounced in the callus on PFD14. Additionally, the PFD14 callus was abnormally enlarged and showed increased deposition of mineralized tissue. Cartilage ossification in the callus was associated with hyper-vascularity and -proliferation. Moreover, cell deposits located in proximity to the callus within skeletal muscle were detected on PFD14. Despite these impairments, repair in EGR-1(-/-) callus advanced on PFD28, suggesting EGR-1 is not essential for healing. Together, this study provides genetic evidence that EGR-1 is a pleiotropic regulator of endochondral fracture repair. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Treating Wastewater With Immobilized Enzymes

    Science.gov (United States)

    Jolly, Clifford D.

    1991-01-01

    Experiments show enzymes are immobilized on supporting materials to make biocatalyst beds for treatment of wastewater. With suitable combination of enzymes, concentrations of various inorganic and organic contaminants, including ammonia and urea, reduced significantly.

  11. Laparoscopic repair for vesicouterine fistulae

    Directory of Open Access Journals (Sweden)

    Rafael A. Maioli

    2015-10-01

    Full Text Available ABSTRACT Objective: The purpose of this video is to present the laparoscopic repair of a VUF in a 42-year-old woman, with gross hematuria, in the immediate postoperative phase following a cesarean delivery. The obstetric team implemented conservative management, including Foley catheter insertion, for 2 weeks. She subsequently developed intermittent hematuria and cystitis. The urology team was consulted 15 days after cesarean delivery. Cystoscopy indicated an ulcerated lesion in the bladder dome of approximately 1.0cm in size. Hysterosalpingography and a pelvic computed tomography scan indicated a fistula. Materials and Methods: Laparoscopic repair was performed 30 days after the cesarean delivery. The patient was placed in the lithotomy position while also in an extreme Trendelenburg position. Pneumoperitoneum was established using a Veress needle in the midline infra-umbilical region, and a primary 11-mm port was inserted. Another 11-mm port was inserted exactly between the left superior iliac spine and the umbilicus. Two other 5-mm ports were established under laparoscopic guidance in the iliac fossa on both sides. The omental adhesions in the pelvis were carefully released and the peritoneum between the bladder and uterus was incised via cautery. Limited cystotomy was performed, and the specific sites of the fistula and the ureteral meatus were identified; thereafter, the posterior bladder wall was adequately mobilized away from the uterus. The uterine rent was then closed using single 3/0Vicryl sutures and two-layer watertight closure of the urinary bladder was achieved by using 3/0Vicryl sutures. An omental flap was mobilized and inserted between the uterus and the urinary bladder, and was fixed using two 3/0Vicryl sutures, followed by tube drain insertion. Results: The operative time was 140 min, whereas the blood loss was 100ml. The patient was discharged 3 days after surgery, and the catheter was removed 12 days after surgery

  12. Structure of Bacterial LigD -phosphoesterase Unveils a DNA Repair Superfamily

    Energy Technology Data Exchange (ETDEWEB)

    Nair, P.; Smith, P; Shuman, S

    2010-01-01

    The DNA ligase D (LigD) 3{prime}-phosphoesterase (PE) module is a conserved component of the bacterial nonhomologous end-joining (NHEJ) apparatus that performs 3{prime} end-healing reactions at DNA double-strand breaks. Here we report the 1.9 {angstrom} crystal structure of Pseudomonas aeruginosa PE, which reveals that PE exemplifies a unique class of DNA repair enzyme. PE has a distinctive fold in which an eight stranded {beta} barrel with a hydrophobic interior supports a crescent-shaped hydrophilic active site on its outer surface. Six essential side chains coordinate manganese and a sulfate mimetic of the scissile phosphate. The PE active site and mechanism are unique vis a vis other end-healing enzymes. We find PE homologs in archaeal and eukaryal proteomes, signifying that PEs comprise a DNA repair superfamily.

  13. A Collective Review on Mesh-Based Repair of Umbilical and Epigastric Hernias.

    Science.gov (United States)

    Ponten, Jeroen E H; Thomassen, Irene; Nienhuijs, Simon W

    2014-10-01

    In accordance with the tension-free principles for other hernias, umbilical and epigastric hernia repair should probably be mesh-based. The number of randomized studies is increasing, most of them showing significantly less recurrences with the use of a mesh. Different devices are available and are applicable by several approaches. The objective of this review was to evaluate recent literature for the different types of mesh for umbilical and epigastric hernia repair and recurrences after mesh repair. A multi-database search was conducted to reveal relevant studies since 2001 reporting mesh-based repair of primary umbilical/epigastric hernia and their outcomes in adult patients. A total of 20 studies were included, 15 of them solely involved umbilical hernias, whereas the remaining studies included epigastric hernias as well. A median of 124 patients (range, 17-384) was investigated per study. Three quarters of the included studies had a follow-up of at least 2 years. Six studies described the results of laparoscopic approach, of which one reported a recurrence rate of 2.7 %; in the remaining studies, no recurrences occurred. Two comparative studies reported a lower incidence of complications and postoperative pain after laparoscopic repair compared to open repair. Seventeen studies reported results of open techniques, of which seven studies showed no recurrence. Other studies reported recurrence rates up to 3.1 %. A wide range of complication rates were reported (0-33 %). This collective review showed acceptable recurrence rates for mesh-based umbilical and epigastric hernia repair. A wide range of devices was investigated. A tendency toward more complications after laparoscopic repair was found compared to open repair.

  14. Mechanistic Modelling and Bayesian Inference Elucidates the Variable Dynamics of Double-Strand Break Repair

    Science.gov (United States)

    2016-01-01

    DNA double-strand breaks are lesions that form during metabolism, DNA replication and exposure to mutagens. When a double-strand break occurs one of a number of repair mechanisms is recruited, all of which have differing propensities for mutational events. Despite DNA repair being of crucial importance, the relative contribution of these mechanisms and their regulatory interactions remain to be fully elucidated. Understanding these mutational processes will have a profound impact on our knowledge of genomic instability, with implications across health, disease and evolution. Here we present a new method to model the combined activation of non-homologous end joining, single strand annealing and alternative end joining, following exposure to ionising radiation. We use Bayesian statistics to integrate eight biological data sets of double-strand break repair curves under varying genetic knockouts and confirm that our model is predictive by re-simulating and comparing to additional data. Analysis of the model suggests that there are at least three disjoint modes of repair, which we assign as fast, slow and intermediate. Our results show that when multiple data sets are combined, the rate for intermediate repair is variable amongst genetic knockouts. Further analysis suggests that the ratio between slow and intermediate repair depends on the presence or absence of DNA-PKcs and Ku70, which implies that non-homologous end joining and alternative end joining are not independent. Finally, we consider the proportion of double-strand breaks within each mechanism as a time series and predict activity as a function of repair rate. We outline how our insights can be directly tested using imaging and sequencing techniques and conclude that there is evidence of variable dynamics in alternative repair pathways. Our approach is an important step towards providing a unifying theoretical framework for the dynamics of DNA repair processes. PMID:27741226

  15. The retrohoming of linear group II intron RNAs in Drosophila melanogaster occurs by both DNA ligase 4-dependent and -independent mechanisms.

    Directory of Open Access Journals (Sweden)

    Travis B White

    Full Text Available Mobile group II introns are bacterial retrotransposons that are thought to have invaded early eukaryotes and evolved into introns and retroelements in higher organisms. In bacteria, group II introns typically retrohome via full reverse splicing of an excised intron lariat RNA into a DNA site, where it is reverse transcribed by the intron-encoded protein. Recently, we showed that linear group II intron RNAs, which can result from hydrolytic splicing or debranching of lariat RNAs, can retrohome in eukaryotes by performing only the first step of reverse splicing, ligating their 3' end to the downstream DNA exon. Reverse transcription then yields an intron cDNA, whose free end is linked to the upstream DNA exon by an error-prone process that yields junctions similar to those formed by non-homologous end joining (NHEJ. Here, by using Drosophila melanogaster NHEJ mutants, we show that linear intron RNA retrohoming occurs by major Lig4-dependent and minor Lig4-independent mechanisms, which appear to be related to classical and alternate NHEJ, respectively. The DNA repair polymerase θ plays a crucial role in both pathways. Surprisingly, however, mutations in Ku70, which functions in capping chromosome ends during NHEJ, have only moderate, possibly indirect effects, suggesting that both Lig4 and the alternate end-joining ligase act in some retrohoming events independently of Ku. Another potential Lig4-independent mechanism, reverse transcriptase template switching from the intron RNA to the upstream exon DNA, occurs in vitro, but gives junctions differing from the majority in vivo. Our results show that group II introns can utilize cellular NHEJ enzymes for retromobility in higher organisms, possibly exploiting mechanisms that contribute to retrotransposition and mitigate DNA damage by resident retrotransposons. Additionally, our results reveal novel activities of group II intron reverse transcriptases, with implications for retrohoming mechanisms and

  16. Extensor tendon repair an overview

    Directory of Open Access Journals (Sweden)

    Mansoor Bin Fayed

    2015-04-01

    Full Text Available The incidence of extensor injuries is more than that of flexor tendon injuries. This is to a great extent because of the extensors being superficially placed and covered by skin and subcutaneous tissue over the distal part of the upper extremity. Thus they are more vulnerable to blunt and sharp trauma, the proximal and distal forearm present with laceration and cut with sharp weapon. Extensor tendon injuries are often taken lightly by many, repairs being taken-up at the ER. Repair is done in or if the retrieval of tendon ends is difficult or the wound is complicated with associated injuries such as fractures or in cases of tendon retraction. Delayed primary repair can be undertaken from 7-10 days. Assessment of the injured finger has to be very meticulous. Extension of finger is brought about by the interossei and lumbricals which are the short muscles of the hand. They extend the proximal interphalangeal joints and distal interphalangeal joints and flex metacarpophalangeal joint, these intrinsic muscles are innervated by the ulnar and median nerves. The long extensors are innervated by the radial nerve, they primarily extend the metacarpophalangeal joints and also interphalangeal joints. In cases of injury the intrinsic system may compensate for an extensor deficit. Closed injuries of zone I may be managed by splinting of the distal interphalangeal joints and open injuries in the zone I and II can be treated with tenodermodesis. Proximal interphalangeal joints and distal interphalangeal joints are immobilized in zone 3 and 4. Metacarpophalangeal joint is immobilized in full extension and the wrist in 10o extension.

  17. Integrated Electrical Wire Insulation Repair System

    Science.gov (United States)

    Williams, Martha; Jolley, Scott; Gibson, Tracy; Parks, Steven

    2013-01-01

    An integrated system tool will allow a technician to easily and quickly repair damaged high-performance electrical wire insulation in the field. Low-melt polyimides have been developed that can be processed into thin films that work well in the repair of damaged polyimide or fluoropolymer insulated electrical wiring. Such thin films can be used in wire insulation repairs by affixing a film of this low-melt polyimide to the damaged wire, and heating the film to effect melting, flow, and cure of the film. The resulting repair is robust, lightweight, and small in volume. The heating of this repair film is accomplished with the use of a common electrical soldering tool that has been modified with a special head or tip that can accommodate the size of wire being repaired. This repair method can furthermore be simplified for the repair technician by providing replaceable or disposable soldering tool heads that have repair film already "loaded" and ready for use. The soldering tool heating device can also be equipped with a battery power supply that will allow its use in areas where plug-in current is not available

  18. Concrete structures protection, repair and rehabilitation

    CERN Document Server

    Woodson, R Dodge

    2009-01-01

    The success of a repair or rehabilitation project depends on the specific plans designed for it. Concrete Structures: Protection, Repair and Rehabilitation provides guidance on evaluating the condition of the concrete in a structure, relating the condition of the concrete to the underlying cause or causes of that condition, selecting an appropriate repair material and method for any deficiency found, and using the selected materials and methods to repair or rehabilitate the structure. Guidance is also provided for engineers focused on maintaining concrete and preparing concrete investigation r

  19. 33 CFR 127.405 - Repairs.

    Science.gov (United States)

    2010-07-01

    ... FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS Waterfront Facilities Handling Liquefied Natural Gas Maintenance § 127.405 Repairs. The operator shall ensure that—...

  20. ONSTEP versus laparoscopy for inguinal hernia repair

    DEFF Research Database (Denmark)

    Andresen, Kristoffer; Burcharth, Jakob; Rosenberg, Jacob

    2015-01-01

    INTRODUCTION: The optimal repair of inguinal hernias remains controversial. It is recommended that an inguinal hernia be repaired using a mesh, either with a laparoscopic or an open approach. In Denmark, the laparoscopic approach is used in an increasing number of cases. The laparoscopic repair has...... clinical trial described in this protocol is to evaluate chronic pain after inguinal hernia repair using the ONSTEP method versus the laparoscopic approach. METHODS: This study is designed as a non-inferiority, two-arm, multicentre, randomised clinical trial, with a 1:1 allocation to ONSTEP or laparoscopic...

  1. Vesicocervical fistula following vesicovaginal fistula repair report

    Directory of Open Access Journals (Sweden)

    Hamudur Rahman

    2016-07-01

    Full Text Available Vesicocervical fistula following vesicovaginal fistula repair is a very rare condition. It is a complication following repeated lower uterine cesarean section. We report a case of an young married woman who was admitted in the depart­ment of urology, Banghabandhu Sheikh Mujib Medical University Hospital with vesico-cervical fistula following vesico­vaginal fistula repair. Reposition of cervix into vaginal vault and repair of urinary bladder was done. There was no such report of vesicocervical fistula following vesicovaginal fistula repair from Bangladesh.

  2. ONSTEP versus laparoscopy for inguinal hernia repair

    DEFF Research Database (Denmark)

    Andresen, Kristoffer; Burcharth, Jakob; Rosenberg, Jacob

    2015-01-01

    INTRODUCTION: The optimal repair of inguinal hernias remains controversial. It is recommended that an inguinal hernia be repaired using a mesh, either with a laparoscopic or an open approach. In Denmark, the laparoscopic approach is used in an increasing number of cases. The laparoscopic repair has...... clinical trial described in this protocol is to evaluate chronic pain after inguinal hernia repair using the ONSTEP method versus the laparoscopic approach. METHODS: This study is designed as a non-inferiority, two-arm, multicentre, randomised clinical trial, with a 1:1 allocation to ONSTEP or laparoscopic...

  3. Complex networks repair strategies: Dynamic models

    Science.gov (United States)

    Fu, Chaoqi; Wang, Ying; Gao, Yangjun; Wang, Xiaoyang

    2017-09-01

    Network repair strategies are tactical methods that restore the efficiency of damaged networks; however, unreasonable repair strategies not only waste resources, they are also ineffective for network recovery. Most extant research on network repair focuses on static networks, but results and findings on static networks cannot be applied to evolutionary dynamic networks because, in dynamic models, complex network repair has completely different characteristics. For instance, repaired nodes face more severe challenges, and require strategic repair methods in order to have a significant effect. In this study, we propose the Shell Repair Strategy (SRS) to minimize the risk of secondary node failures due to the cascading effect. Our proposed method includes the identification of a set of vital nodes that have a significant impact on network repair and defense. Our identification of these vital nodes reduces the number of switching nodes that face the risk of secondary failures during the dynamic repair process. This is positively correlated with the size of the average degree and enhances network invulnerability.

  4. Root justifications for ontology repair

    CSIR Research Space (South Africa)

    Moodley, K

    2011-08-01

    Full Text Available stream_source_info Moodley_2011.pdf.txt stream_content_type text/plain stream_size 32328 Content-Encoding ISO-8859-1 stream_name Moodley_2011.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Root Justi cations... the ontology, based on the no- tion of root justi cations [8, 9]. In Section 5, we discuss the implementation of a Prot eg e3 plugin which demonstrates our approach to ontology repair. In this section we also discuss some experimental results comparing...

  5. Arthroscopic Transosseous Bony Bankart Repair

    Science.gov (United States)

    Driscoll, Matthew D.; Burns, Joseph P.; Snyder, Stephen J.

    2015-01-01

    Restoration of glenoid bony integrity is critical to minimizing the risk of recurrence and re-creating normal kinematics in the setting of anterior glenohumeral instability. We present an arthroscopic suture anchor–based technique for treating large bony Bankart fractures in which the fragment is secured to the intact glenoid using mattress sutures placed through the bony fragment and augmented with soft-tissue repair proximal and distal to the bony lesion. This straightforward technique has led to excellent fragment reduction and good outcomes in our experience. PMID:25973373

  6. Early Steps in the DNA Base Excision Repair Pathway of a Fission Yeast Schizosaccharomyces pombe

    Directory of Open Access Journals (Sweden)

    Kyoichiro Kanamitsu

    2010-01-01

    Full Text Available DNA base excision repair (BER accounts for maintaining genomic integrity by removing damaged bases that are generated endogenously or induced by genotoxic agents. In this paper, we describe the roles of enzymes functioning in the early steps of BER in fission yeast. Although BER is an evolutionarily conserved process, some unique features of the yeast repair pathway were revealed by genetic and biochemical approaches. AP sites generated by monofunctional DNA glycosylases are incised mainly by AP lyase activity of Nth1p, a sole bifunctional glycosylase in yeast, to leave a blocked 3′ end. The major AP endonuclease Apn2p functions predominantly in removing the 3′ block. Finally, a DNA polymerase fills the gap, and a DNA ligase seals the nick (Nth1p-dependent or short patch BER. Apn1p backs up Apn2p. In long patch BER, Rad2p endonuclease removes flap DNA containing a lesion after DNA synthesis. A UV-specific endonuclease Uve1p engages in an alternative pathway by nicking DNA on the 5′ side of oxidative damage. Nucleotide excision repair and homologous recombination are involved in repair of BER intermediates including the AP site and single-strand break with the 3′ block. Other enzymes working in 3′ end processing are also discussed.

  7. Effect of heat shock on poly(ADP-ribose) synthetase and DNA repair in Drosophila cells

    Energy Technology Data Exchange (ETDEWEB)

    Nolan, N.L.; Kidwell, W.R.

    1982-04-01

    Poly(ADP-ribose) synthetase, a chromatin-bound enzyme which attaches polyanionic chains of ADP-ribose to nuclear proteins, was found to be temperature sensitive in intact Drosophila melanogaster cells. The synthetase was completely inactivated by heat-shocking the cells at 37/sup 0/C for 5 min, a condition which had no appreciable effect on the subsequent growth of Drosophila cells at their physiological temperature. The heat-shock effect on synthetase was reversible; enzyme activity began to reappear about 2 hr post heat shock. During the 2-hr interval when poly(ADP-ribose) synthetase was absent, the cells were competent in repair of ..gamma..-ray-induced DNA strand breaks as shown by DNA sedimentation studies on alkaline sucrose gradients. It is thus concluded that poly(ADP-ribose) synthesis is unnecessary for repair of DNA strand breaks introduced by irradiation. The same conclusion was reached from the fact that two inhibitors of poly(ADP-ribose) synthetase 3-aminobenzamide and 5-methylnicotinamide, failed to block repair of ..gamma..-ray-induced DNA chain breaks even though both inhibitors reduced the amount of poly(ADP-ribose) synthesized in cells by 50-75%. Although it was found that the repair of DNA strand breaks is independent of poly(ADP-ribose) synthesis, irradiation does activate the synthetase in control cells, as shown by radioimmunoassay of poly(ADP-ribose) levels.

  8. On the Temperature Dependence of Enzyme-Catalyzed Rates.

    Science.gov (United States)

    Arcus, Vickery L; Prentice, Erica J; Hobbs, Joanne K; Mulholland, Adrian J; Van der Kamp, Marc W; Pudney, Christopher R; Parker, Emily J; Schipper, Louis A

    2016-03-29

    One of the critical variables that determine the rate of any reaction is temperature. For biological systems, the effects of temperature are convoluted with myriad (and often opposing) contributions from enzyme catalysis, protein stability, and temperature-dependent regulation, for example. We have coined the phrase "macromolecular rate theory (MMRT)" to describe the temperature dependence of enzyme-catalyzed rates independent of stability or regulatory processes. Central to MMRT is the observation that enzyme-catalyzed reactions occur with significant values of ΔCp(‡) that are in general negative. That is, the heat capacity (Cp) for the enzyme-substrate complex is generally larger than the Cp for the enzyme-transition state complex. Consistent with a classical description of enzyme catalysis, a negative value for ΔCp(‡) is the result of the enzyme binding relatively weakly to the substrate and very tightly to the transition state. This observation of negative ΔCp(‡) has important implications for the temperature dependence of enzyme-catalyzed rates. Here, we lay out the fundamentals of MMRT. We present a number of hypotheses that arise directly from MMRT including a theoretical justification for the large size of enzymes and the basis for their optimum temperatures. We rationalize the behavior of psychrophilic enzymes and describe a "psychrophilic trap" which places limits on the evolution of enzymes in low temperature environments. One of the defining characteristics of biology is catalysis of chemical reactions by enzymes, and enzymes drive much of metabolism. Therefore, we also expect to see characteristics of MMRT at the level of cells, whole organisms, and even ecosystems.

  9. 40 CFR 60.482-9 - Standards: Delay of repair.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Delay of repair. 60.482-9... Standards: Delay of repair. (a) Delay of repair of equipment for which leaks have been detected will be allowed if repair within 15 days is technically infeasible without a process unit shutdown. Repair of...

  10. 21 CFR 870.1350 - Catheter balloon repair kit.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Catheter balloon repair kit. 870.1350 Section 870... repair kit. (a) Identification. A catheter balloon repair kit is a device used to repair or replace the... effect the repair or replacement. (b) Classification. Class III (premarket approval). (c) Date PMA...

  11. 14 CFR 145.207 - Repair station manual.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Repair station manual. 145.207 Section 145...) SCHOOLS AND OTHER CERTIFICATED AGENCIES REPAIR STATIONS Operating Rules § 145.207 Repair station manual. (a) A certificated repair station must prepare and follow a repair station manual acceptable to...

  12. The Catalytic Function of Enzymes.

    Science.gov (United States)

    Splittgerber, Allan G.

    1985-01-01

    Discusses: structure of the enzyme molecule; active site; reaction mechanism; transition state; factors affecting enzyme reaction rates, concentration of enzyme; concentration of substrate; product concentration; temperature effects and pH effects; factors causing a lowering of activation energy; proximity and orientation effects; substrate strain…

  13. Mid-term results after endovascular repair of abdominal aortic aneurysms: a four-year experience.

    Science.gov (United States)

    Dalainas, I; Nano, G; Casana, R; Tealdi Dg, D g

    2004-03-01

    The purpose of this retrospective, single-institution study is to describe a 4-year experience of examining early and late clinical outcomes after endovascular repair of abdominal aortic aneurysm (AAA). Between October 1998 and January 2003, 455 patients were submitted for AAA treatment, of whom 269 underwent open repair and 186 were treated with an endovascular procedure. All endovascular-treated patients underwent preoperative arteriography, contrast enhanced CT scanning or spiral-CT to define the morphological characteristics of the aneurysm, including precise diameter and length measurements. Technical success was achieved in 182 (98%) of the endovascular procedures, as intraoperative conversions to open repair and/or aborted procedures occurred in four patients. The perioperative (30-day) mortality rate was 1% (two patients). During the follow-up period (9-60 months) CT, duplex ultrasound scanning and plain abdominal X-ray evaluation were performed at 3, 6, 12 months, and annually thereafter. Type I endoleak occurred in 12 patients (6.6%), required a further endovascular procedure (11) or late conversion to open repair (1). Type II endoleak occurred in five patients (3%). In our clinical experience the endovascular repair of AAA is a safe and effective technique with good mid-term results in patients at standard and high risk.

  14. A quantitative model of human DNA base excision repair. I. mechanistic insights

    OpenAIRE

    Sokhansanj, Bahrad A.; Rodrigue, Garry R.; Fitch, J. Patrick; David M Wilson

    2002-01-01

    Base excision repair (BER) is a multistep process involving the sequential activity of several proteins that cope with spontaneous and environmentally induced mutagenic and cytotoxic DNA damage. Quantitative kinetic data on single proteins of BER have been used here to develop a mathematical model of the BER pathway. This model was then employed to evaluate mechanistic issues and to determine the sensitivity of pathway throughput to altered enzyme kinetics. Notably, the model predicts conside...

  15. Maintaining Genetic Integrity Under Extreme Conditions: Novel DNA Damage Repair Biology in the Archaea

    Science.gov (United States)

    2013-11-23

    DeRuggiero (Johns Hopkins University). Chromosome behaviour was monitored in wild-type and ∆nreA cells treated with MMC for 1 hour and during a 10...MacNeill, undergraduate students Agnieszka Janska and Jason Woodier) In bacteria , RecJ has an important role in DNA damage repair, in particular in...is an NAD-dependent enzyme the gene for which was apparently acquired by lateral gene transfer from bacteria . Biochemical analysis of LigN function

  16. CrowdAidRepair: A Crowd-Aided Interactive Data Repairing Method

    KAUST Repository

    Zhou, Jian

    2016-03-25

    Data repairing aims at discovering and correcting erroneous data in databases. Traditional methods relying on predefined quality rules to detect the conflict between data may fail to choose the right way to fix the detected conflict. Recent efforts turn to use the power of crowd in data repairing, but the crowd power has its own drawbacks such as high human intervention cost and inevitable low efficiency. In this paper, we propose a crowd-aided interactive data repairing method which takes the advantages of both rule-based method and crowd-based method. Particularly, we investigate the interaction between crowd-based repairing and rule-based repairing, and show that by doing crowd-based repairing to a small portion of values, we can greatly improve the repairing quality of the rule-based repairing method. Although we prove that the optimal interaction scheme using the least number of values for crowd-based repairing to maximize the imputation recall is not feasible to be achieved, still, our proposed solution identifies an efficient scheme through investigating the inconsistencies and the dependencies between values in the repairing process. Our empirical study on three data collections demonstrates the high repairing quality of CrowdAidRepair, as well as the efficiency of the generated interaction scheme over baselines.

  17. Initiating Repair and Beyond: The Use of Two Repeat-Formatted Repair Initiations in Mandarin Conversation

    Science.gov (United States)

    Wu, Ruey-Jiuan Regina

    2006-01-01

    As part of a growing effort to understand the organization of repair across languages, this study examines 2 repeat-formatted other-initiated repair practices in Mandarin conversation. Using the methodology of conversation analysis as a central framework, this study shows that the 2 Mandarin repair initiations under examination, like…

  18. X-ray repair cross complementing protein 1 in base excision repair

    DEFF Research Database (Denmark)

    Hanssen-Bauer, Audun; Solvang-Garten, Karin; Akbari, Mansour;

    2012-01-01

    X-ray Repair Cross Complementing protein 1 (XRCC1) acts as a scaffolding protein in the converging base excision repair (BER) and single strand break repair (SSBR) pathways. XRCC1 also interacts with itself and rapidly accumulates at sites of DNA damage. XRCC1 can thus mediate the assembly of large...

  19. Excited-state proton coupled electron transfer between photolyase and the damaged DNA through water wire: a photo-repair mechanism.

    Science.gov (United States)

    Wang, Hongjuan; Chen, Xuebo; Fang, Weihai

    2014-12-14

    The photolyase enzyme absorbs blue light to repair damaged DNA through a cyclic electron transfer reaction. A description of the underlying mechanism has proven to be a challenging issue for both experimental and theoretical studies. In the present work, combined CASPT2//CASSCF/AMBER (QM/MM) calculations have been performed for damaged DNA in photolyase. A proton-coupled electron transfer (PCET) mechanism has been determined for restoring cyclobutane pyrimidine dimer (CPD) to two normal thymine bases by irradiation of photolyase. A well-defined water wire between FADH(-) and CPD was determined as a bridge to assist the PCET process within FADH(-) and thereby trigger the forward electron transfer to CPD. The subsequent CPD splitting and the alternation of the H-bond pattern proceed in a concerted way, which makes the productive backward electron transfer occur on an ultrafast timescale. A local minimum of SCT((1)ππ*)-LMin was identified on the pathway of the futile backward electron transfer (BET), which is stabilized by the strong H-bond interaction between the water wire and CPD. As a result, the futile BET process is endothermic by ∼18.0 kcal mol(-1), which is responsible for a 2.4 ns timescale inferred experimentally for the futile BET process. Besides the unbiased interpretation for the majority of the experimental findings, the present study provides a new excited-state PCET mechanism, which leads to a significant step toward a deeper understanding of the photo-repair process of damaged-DNA by the photolyase enzyme.

  20. Kinetic Measurements for Enzyme Immobilization.

    Science.gov (United States)

    Cooney, Michael J

    2017-01-01

    Enzyme kinetics is the study of the chemical reactions that are catalyzed by enzymes, with a focus on their reaction rates. The study of an enzyme's kinetics considers the various stages of activity, reveals the catalytic mechanism of this enzyme, correlates its value to assay conditions, and describes how a drug or a poison might inhibit the enzyme. Victor Henri initially reported that enzyme reactions were initiated by a bond between the enzyme and the substrate. By 1910, Michaelis and Menten were advancing their work by studying the kinetics of an enzyme saccharase which catalyzes the hydrolysis of sucrose into glucose and fructose. They published their analysis and ever since the Michaelis-Menten equation has been used as the standard to describe the kinetics of many enzymes. Unfortunately, soluble enzymes must generally be immobilized to be reused for long times in industrial reactors. In addition, other critical enzyme properties have to be improved like stability, activity, inhibition by reaction products, and selectivity towards nonnatural substrates. Immobilization is by far the chosen process to achieve these goals.Although the Michaelis-Menten approach has been regularly adapted to the analysis of immobilized enzyme activity, its applicability to the immobilized state is limited by the barriers the immobilization matrix places upon the measurement of compounds that are used to model enzyme kinetics. That being said, the estimated value of the Michaelis-Menten coefficients (e.g., V max, K M) can be used to evaluate effects of immobilization on enzyme activity in the immobilized state when applied in a controlled manner. In this review enzyme activity and kinetics are discussed in the context of the immobilized state, and a few novel protocols are presented that address some of the unique constraints imposed by the immobilization barrier.