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Sample records for excision repair defects

  1. Ku80-deleted cells are defective at base excision repair

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    Li, Han [The University of Texas Health Science Center at San Antonio, The Institute of Biotechnology, The Department of Molecular Medicine, 15355 Lambda Drive, San Antonio, TX 78245-3207 (United States); Tumor Suppression Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029 (Spain); Marple, Teresa [The University of Texas Health Science Center at San Antonio, The Institute of Biotechnology, The Department of Molecular Medicine, 15355 Lambda Drive, San Antonio, TX 78245-3207 (United States); Hasty, Paul, E-mail: hastye@uthscsa.edu [The University of Texas Health Science Center at San Antonio, The Institute of Biotechnology, The Department of Molecular Medicine, 15355 Lambda Drive, San Antonio, TX 78245-3207 (United States); Tumor Suppression Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029 (Spain)

    2013-05-15

    Graphical abstract: - Highlights: • Ku80-deleted cells are hypersensitive to ROS and alkylating agents. • Cells deleted for Ku80, but not Ku70 or Lig4, have reduced BER capacity. • OGG1 rescues hypersensitivity to H{sub 2}O{sub 2} and paraquat in Ku80-mutant cells. • Cells deleted for Ku80, but not Lig4, are defective at repairing AP sites. • Cells deleted for Ku80, but not Lig4 or Brca2 exon 27, exhibit increased PAR. - Abstract: Ku80 forms a heterodimer with Ku70, called Ku, that repairs DNA double-strand breaks (DSBs) via the nonhomologous end joining (NHEJ) pathway. As a consequence of deleting NHEJ, Ku80-mutant cells are hypersensitive to agents that cause DNA DSBs like ionizing radiation. Here we show that Ku80 deletion also decreased resistance to ROS and alkylating agents that typically cause base lesions and single-strand breaks (SSBs). This is unusual since base excision repair (BER), not NHEJ, typically repairs these types of lesions. However, we show that deletion of another NHEJ protein, DNA ligase IV (Lig4), did not cause hypersensitivity to these agents. In addition, the ROS and alkylating agents did not induce γ-H2AX foci that are diagnostic of DSBs. Furthermore, deletion of Ku80, but not Lig4 or Ku70, reduced BER capacity. Ku80 deletion also impaired BER at the initial lesion recognition/strand scission step; thus, involvement of a DSB is unlikely. Therefore, our data suggests that Ku80 deletion impairs BER via a mechanism that does not repair DSBs.

  2. Defects in Base Excision Repair Sensitize Cells to Manganese in S. cerevisiae

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    Adrienne P. Stephenson

    2013-01-01

    Full Text Available Manganese (Mn is essential for normal physiologic functioning; therefore, deficiencies and excess intake of manganese can result in disease. In humans, prolonged exposure to manganese causes neurotoxicity characterized by Parkinson-like symptoms. Mn2+ has been shown to mediate DNA damage possibly through the generation of reactive oxygen species. In a recent publication, we showed that Mn induced oxidative DNA damage and caused lesions in thymines. This study further investigates the mechanisms by which cells process Mn2+-mediated DNA damage using the yeast S. cerevisiae. The strains most sensitive to Mn2+ were those defective in base excision repair, glutathione synthesis, and superoxide dismutase mutants. Mn2+ caused a dose-dependent increase in the accumulation of mutations using the CAN1 and lys2-10A mutator assays. The spectrum of CAN1 mutants indicates that exposure to Mn results in accumulation of base substitutions and frameshift mutations. The sensitivity of cells to Mn2+ as well as its mutagenic effect was reduced by N-acetylcysteine, glutathione, and Mg2+. These data suggest that Mn2+ causes oxidative DNA damage that requires base excision repair for processing and that Mn interferes with polymerase fidelity. The status of base excision repair may provide a biomarker for the sensitivity of individuals to manganese.

  3. Nucleotide excision repair in yeast

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    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

  4. REPAIR OF LARGE SKULL BASE DEFECT FOLLOWING EXCISION OF BASALOID SQUAMOUS CELL CARCINOMA OF MAXILLO - ETHMOID REGION : A CASE REPORT

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    Monoj Mukherjee

    2015-02-01

    Full Text Available AIM: To present a case of basaloid squamous cell carcinoma of maxillo - ethmoid region with intracranial extradural extention and its surgical management including repair of the skull base defect. MATERIAL : A 30 year female presented with progressive bilateral nasal obstruction, facial deformity for 5 years duration. She developed blindness in last 6 months. Recent CT s can showed large heterogeneous enhancing soft tissue mass in right maxillary sinus, nasal cavity and right ethmoid sinus invading the skull base . INTERVENTION : She underwent excision of the mass by modified weber ferguson incision and repair of skull base defect with temporalis muscle flap. Skin defect over the face and nose was repaired by median forehead flap. RESULT : There was total tumor clearance and no CSF leakage following surgery. CONCLUSION : Sinonasal malignancy with intracranial extradural extenti on is not a contraindication for successful surgical management. Resultant skull base defect can be repaired by a temporalis muscle flap to prevent CSF leak and intracranial infection

  5. Actual state of knowledge in the field of diseases related with defective nucleotide excision repair.

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    Bukowska, Barbara; Karwowski, Bolesław T

    2018-02-15

    Xeroderma pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne syndrome (CS) are rare genetic diseases characterized by a large range of clinical symptoms. However, they are all associated with defects in nucleotide excision repair (NER), the system responsible for removing bulky DNA lesions such as those generated by UV light: cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone photoproducts (6-4 PPs). Over the past years, detailed structural and biochemical information on NER-associated proteins has emerged. In the first part of the article we briefly present the main steps of the NER pathway with an emphasis on the precise role of certain proteins. Further, we focus on clinical manifestations of the disorders and describe the diagnostic procedures. Then we consider how current therapy and advanced technology could improve patients' quality of life. Although to date the discussed diseases remain incurable, effective sun protection, a well thought out diet, and holistic medical care provide longer life and better health. This review summarizes the current state of knowledge regarding the epidemiology of NER-associated diseases, their genetic background, clinical features, and treatment options. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Incomplete complementation of the DNA repair defect in cockayne syndrome cells by the denV gene from bacteriophage T4 suggests a deficiency in base excision repair.

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    Francis, M A; Bagga, P S; Athwal, R S; Rainbow, A J

    1997-10-01

    Endonuclease V (denV) from bacteriophage T4 has been examined for its ability to complement the repair defect in Cockayne syndrome (CS) cells of complementation groups A and B. CS is an autosomal recessive disorder characterized by hypersensitivity to UV light and a defect in the preferential repair of UV-induced lesions in transcriptionally active DNA by the nucleotide excision repair (NER) pathway. The denV gene was introduced into non-transformed normal and CS fibroblasts transiently via a recombinant adenovirus (Ad) vector and into SV40-transformed normal and CS cells via a retroviral vector. Expression of denV in CS-A cells resulted in partial correction of the UV-sensitive phenotype in assays of gene-specific repair and cell viability, while correction of CS-B cells by expression of denV in the same assays was minimal or non-existent. In contrast, denV expression led to enhanced host cell reactivation (HCR) of viral DNA synthesis in both CS complementation groups to near normal levels. DenV is a glycosylase which is specific for cyclobutane-pyrimidine dimers (CPDs) but does not recognize other UV-induced lesions. Previous work has indicated that CS cells can efficiently repair all non-CPD UV-induced transcription blocking lesions (S.F. Barrett et al.. Mutation Res. 255 (1991) 281-291 [1]) and that denV incised lesions are believed to be processed via the base excision repair (BER) pathway. The inability of denV to complement the NER defect in CS cells to normal levels implies an impaired ability to process denV incised lesions by the BER pathway, and suggests a role for the CS genes, particularly the CS-B gene, in BER.

  7. First reported patient with human ERCC1 deficiency has cerebro-oculo-facio- skeletal syndrome with a mild defect in nucleotide excision repair and severe developmental failure

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    N.G.J. Jaspers (Nicolaas); A. Raams (Anja); M.C. Silengo; N. Wijgers (Nils); L.J. Niedernhofer (Laura); A.R. Robinson (Andria Rasile); G. Giglia-Mari (Giuseppina); D. Hoogstraten (Deborah); W.J. Kleijer (Wim); J.H.J. Hoeijmakers (Jan); W. Vermeulen (Wim)

    2007-01-01

    textabstractNucleotide excision repair (NER) is a genome caretaker mechanism responsible for removing helix-distorting DNA lesions, most notably ultraviolet photodimers. Inherited defects in NER result in profound photosensitivity and the cancer-prone syndrome xeroderma pigmentosum (XP) or two

  8. Variation in Base Excision Repair Capacity

    OpenAIRE

    Wilson, David M.; Kim, Daemyung; Berquist, Brian R.; Sigurdson, Alice J.

    2010-01-01

    The major DNA repair pathway for coping with spontaneous forms of DNA damage, such as natural hydrolytic products or oxidative lesions, is base excision repair (BER). In particular, BER processes mutagenic and cytotoxic DNA lesions such as non-bulky base modifications, abasic sites, and a range of chemically distinct single-strand breaks. Defects in BER have been linked to cancer predisposition, neurodegenerative disorders, and immunodeficiency. Recent data indicate a large degree of sequence...

  9. First Reported Patient with Human ERCC1 Deficiency Has Cerebro-Oculo-Facio-Skeletal Syndrome with a Mild Defect in Nucleotide Excision Repair and Severe Developmental Failure

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    Jaspers, Nicolaas G.J.; Raams, Anja; Silengo, Margherita Cirillo; Wijgers, Nils; Niedernhofer, Laura J; Robinson, Andria Rasile; Giglia-Mari, Giuseppina; Hoogstraten, Deborah; Kleijer, Wim J.; Hoeijmakers, Jan H.J.; Vermeulen, Wim

    2007-01-01

    Nucleotide excision repair (NER) is a genome caretaker mechanism responsible for removing helix-distorting DNA lesions, most notably ultraviolet photodimers. Inherited defects in NER result in profound photosensitivity and the cancer-prone syndrome xeroderma pigmentosum (XP) or two progeroid syndromes: Cockayne and trichothiodystrophy syndromes. The heterodimer ERCC1-XPF is one of two endonucleases required for NER. Mutations in XPF are associated with mild XP and rarely with progeria. Mutati...

  10. Molecular spectrum of excision repair cross-complementation group 8 gene defects in Chinese patients with Cockayne syndrome type A.

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    Wang, Xiaozhu; Huang, Yu; Yan, Ming; Li, Jiuwei; Ding, Changhong; Jin, Hong; Fang, Fang; Yang, Yanling; Wu, Baiyan; Chen, Dafang

    2017-10-20

    There are two genetics complementary groups Cockayne syndrome type A and B (CS-A and CS-B OMIM 216400, 133540), which is a rare autosomal recessive segmental progeroid syndrome. Homozygous or compound heterozygous mutations in the excision repair cross-complementation group 8 gene (ERCC8) result in CS-A, and mutations in ERCC6 result in CS-B. Homozygous ERCC6/ERCC8 mutations also result in UV-sensitive syndrome. In this study, twenty-one Han Chinese patients with CS were investigated to identify mutations in ERCC8/ERCC6, of which thirteen cases with CS-A were identified with the mutations of ERCC8. There are five types mutations of ERCC8 in our study, such as exon 4 rearrangement, c.394_398delTTACA, c.299insA, c.843 + 2 T > C, and c.2 T > A. An estimated frequency of exon 4 rearrangement accounts for 69.23% and c.394_398delTTACA accounts for 11.53% in our cohort. Haplotype analysis revealed that the exon 4 rearrangement and c.394_398delTTACA mutations originated from a common founder in the Chinese population respectively. With the identification of three novel ERCC8 mutations, this study expanded the molecular spectrum of known ERCC8 defects, and furthermore, suggests that the exon 4 rearrangement and c.394_398delTTACA mutations may be a common underlying cause of CS-A in the Chinese population, which is different from that in other populations.

  11. First reported patient with human ERCC1 deficiency has cerebro-oculo-facio-skeletal syndrome with a mild defect in nucleotide excision repair and severe developmental failure.

    Science.gov (United States)

    Jaspers, Nicolaas G J; Raams, Anja; Silengo, Margherita Cirillo; Wijgers, Nils; Niedernhofer, Laura J; Robinson, Andria Rasile; Giglia-Mari, Giuseppina; Hoogstraten, Deborah; Kleijer, Wim J; Hoeijmakers, Jan H J; Vermeulen, Wim

    2007-03-01

    Nucleotide excision repair (NER) is a genome caretaker mechanism responsible for removing helix-distorting DNA lesions, most notably ultraviolet photodimers. Inherited defects in NER result in profound photosensitivity and the cancer-prone syndrome xeroderma pigmentosum (XP) or two progeroid syndromes: Cockayne and trichothiodystrophy syndromes. The heterodimer ERCC1-XPF is one of two endonucleases required for NER. Mutations in XPF are associated with mild XP and rarely with progeria. Mutations in ERCC1 have not been reported. Here, we describe the first case of human inherited ERCC1 deficiency. Patient cells showed moderate hypersensitivity to ultraviolet rays and mitomycin C, yet the clinical features were very severe and, unexpectedly, were compatible with a diagnosis of cerebro-oculo-facio-skeletal syndrome. This discovery represents a novel complementation group of patients with defective NER. Further, the clinical severity, coupled with a relatively mild repair defect, suggests novel functions for ERCC1.

  12. Molecular spectrum of excision repair cross-complementation group 8 gene defects in Chinese patients with Cockayne syndrome type A

    OpenAIRE

    Wang, Xiaozhu; Huang, Yu; Yan, Ming; Li, Jiuwei; Ding, Changhong; Jin, Hong; Fang, Fang; Yang, Yanling; Wu, Baiyan; Chen, Dafang

    2017-01-01

    There are two genetics complementary groups Cockayne syndrome type A and B (CS-A and CS-B OMIM 216400, 133540), which is a rare autosomal recessive segmental progeroid syndrome. Homozygous or compound heterozygous mutations in the excision repair cross-complementation group 8 gene (ERCC8) result in CS-A, and mutations in ERCC6 result in CS-B. Homozygous ERCC6/ERCC8 mutations also result in UV-sensitive syndrome. In this study, twenty-one Han Chinese patients with CS were investigated to ident...

  13. Mitochondrial base excision repair assays

    DEFF Research Database (Denmark)

    Maynard, Scott; de Souza-Pinto, Nadja C; Scheibye-Knudsen, Morten

    2010-01-01

    The main source of mitochondrial DNA (mtDNA) damage is reactive oxygen species (ROS) generated during normal cellular metabolism. The main mtDNA lesions generated by ROS are base modifications, such as the ubiquitous 8-oxoguanine (8-oxoG) lesion; however, base loss and strand breaks may also occur....... Many human diseases are associated with mtDNA mutations and thus maintaining mtDNA integrity is critical. All of these lesions are repaired primarily by the base excision repair (BER) pathway. It is now known that mammalian mitochondria have BER, which, similarly to nuclear BER, is catalyzed by DNA...

  14. B lymphocytes of xeroderma pigmentosum or Cockayne syndrome patients with inherited defects in nucleotide excision repair are fully capable of somatic hypermutation of immunoglobulin genes.

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    Kim, N; Kage, K; Matsuda, F; Lefranc, M P; Storb, U

    1997-08-04

    Recent experiments have strongly suggested that the process of somatic mutation is linked to transcription initiation. It was postulated that a mutator factor loads onto the RNA polymerase and, during elongation, causes transcriptional arrest that activates DNA repair, thus occasionally causing errors in the DNA sequence. We report the analysis of the role of one of the known DNA repair systems, nucleotide excision repair (NER), in somatic mutation. Epstein-Barrvirus-transformed B cells from patients with defects in NER (XP-B, XP-D, XP-V, and CS-A) were studied. Their heavy and light chain genes show a high frequency of point mutations in the variable (V), but not in the constant (C) regions. This suggests that these B cells can undergo somatic hypermutation despite significant defects in NER. Thus, it is doubtful that NER is an essential part of the mechanism of somatic hypermutation of Ig genes. As an aside, NER seems also not involved in Ig gene switch recombination.

  15. Reconstruction Techniques for Tissue Defects Formed after Preauricular Sinus Excision

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    Myung Joon Lee

    2014-01-01

    Full Text Available Background Preauricular sinuses are congenital abnormalities caused by a failure of fusion of the primitive tubercles from which the pinna is formed. When persistent or recurring inflammation occurs, surgical excision of the infected tissue should be considered. Preauricular defects inevitably occur as a result of excisions and are often difficult to resolve with a simple suture; a more effective reconstruction technique is required for treating these defects. Methods After total excision of a preauricular sinus, the defect was closed by a plastic surgeon. Based on the depth of the defect and the degree of tension when apposing the wound margins, the surgeon determined whether to use primary closure or a posterior auricular flap. Results A total of 28 cases were examined. In 5 cases, including 2 reoperations for dehiscence after primary repair, reconstruction was performed using posterior auricular transposition flaps. In 16 cases of primary closure, the defects were closed using simple sutures, and in 7 cases, closure was performed after wide undermining. Conclusions If a preauricular defect is limited to the subcutaneous layer and the margins can be easily approximated, primary closure by only simple suturing may be used to perform the repair. If the defect is deep enough to expose the perichondrium or if there is tension when apposing the wound margins, wide undermining should be performed before primary closure. If the extent of the excision exposes cartilage, the procedure follows dehiscence of the primary repair, or the tissue is not sufficiently healthy, the surgeon should use a posterior auricular flap.

  16. Mammalian Transcription-Coupled Excision Repair

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    Vermeulen, Wim; Fousteri, Maria

    2013-01-01

    Transcriptional arrest caused by DNA damage is detrimental for cells and organisms as it impinges on gene expression and thereby on cell growth and survival. To alleviate transcriptional arrest, cells trigger a transcription-dependent genome surveillance pathway, termed transcription-coupled nucleotide excision repair (TC-NER) that ensures rapid removal of such transcription-impeding DNA lesions and prevents persistent stalling of transcription. Defective TC-NER is causatively linked to Cockayne syndrome, a rare severe genetic disorder with multisystem abnormalities that results in patients’ death in early adulthood. Here we review recent data on how damage-arrested transcription is actively coupled to TC-NER in mammals and discuss new emerging models concerning the role of TC-NER-specific factors in this process. PMID:23906714

  17. Nucleotide excision repair and human syndromes

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    J. de Boer (Jan); J.H.J. Hoeijmakers (Jan)

    2000-01-01

    textabstractDNA damage is implicated in cancer and aging, and several DNA repair mechanisms exist that safeguard the genome from these deleterious consequences. Nucleotide excision repair (NER) removes a wide diversity of lesions, the main of which include UV-induced lesions, bulky chemical adducts

  18. Nucleotide Excision Repair in Caenorhabditis elegans

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    Hannes Lans

    2011-01-01

    Full Text Available Nucleotide excision repair (NER plays an essential role in many organisms across life domains to preserve and faithfully transmit DNA to the next generation. In humans, NER is essential to prevent DNA damage-induced mutation accumulation and cell death leading to cancer and aging. NER is a versatile DNA repair pathway that repairs many types of DNA damage which distort the DNA helix, such as those induced by solar UV light. A detailed molecular model of the NER pathway has emerged from in vitro and live cell experiments, particularly using model systems such as bacteria, yeast, and mammalian cell cultures. In recent years, the versatility of the nematode C. elegans to study DNA damage response (DDR mechanisms including NER has become increasingly clear. In particular, C. elegans seems to be a convenient tool to study NER during the UV response in vivo, to analyze this process in the context of a developing and multicellular organism, and to perform genetic screening. Here, we will discuss current knowledge gained from the use of C. elegans to study NER and the response to UV-induced DNA damage.

  19. Laparoscopic Excision of a Scar Pregnancy and Isthmocele Repair.

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    Kiyak, Huseyin; Wetherilt, Lale Susan; Seckin, Kerem Doga; Polat, Ibrahim; Kadirogullari, Pınar; Karacan, Tolga

    2017-10-13

    Laparoscopic excision of a scar pregnancy and isthmocele repair with a barbed suture. A step-by-step explanation of the laparoscopic excision technique of a scar pregnancy and isthmocele repair. Cesarean scar pregnancy occurs as a result of attachment of the products of conception to the uterine scar [1-3]. In the present case, a 34-year-old, gravida 4, para 1 patient with a history of 1 miscarriage and 1 ectopic pregnancy was diagnosed with type 2 cesarean scar pregnancy at 7 weeks of gestation. Dilation and curretage was performed at the 8th week of gestation to terminate the pregnancy. On ultrasonography performed 1 month later, placental material underlying the isthmocele was observed. Her beta human chorionic gonadotropin level was 13 836 mIU/mL. She was followed up for 1.5 months until the beta human chorionic gonadotropin levels were negative. However, the mass underneath the scar had grown larger, measuring up to 5 × 6 cm. Laparoscopy was performed because the patient reported vaginal spotting and pelvic pain. The incision was sutured with a synthetic absorbable unidirectional barbed suture (Stratafix Knotless Tissue Control Device; Ethicon Inc., Somerville, NJ). No residual scar defect was visible on follow-up ultrasonography 1 week and 1 month after surgery. Barbed sutures ease the repair of uterine scar defects and can provide ideal reapproximation of thick myometrial tissue. Laparoscopic treatment of a scar pregnancy and isthmocele repair are effective and safe modes of treatment. Copyright © 2017 American Association of Gynecologic Laparoscopists. Published by Elsevier Inc. All rights reserved.

  20. Emerging roles for histone modifications in DNA excision repair.

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    Mao, Peng; Wyrick, John J

    2016-11-01

    DNA repair is critical to maintain genome stability. In eukaryotic cells, DNA repair is complicated by the packaging of the DNA 'substrate' into chromatin. DNA repair pathways utilize different mechanisms to overcome the barrier presented by chromatin to efficiently locate and remove DNA lesions in the genome. DNA excision repair pathways are responsible for repairing a majority of DNA lesions arising in the genome. Excision repair pathways include nucleotide excision repair (NER) and base excision repair (BER), which repair bulky and non-bulky DNA lesions, respectively. Numerous studies have suggested that chromatin inhibits both NER and BER in vitro and in vivo Growing evidence demonstrates that histone modifications have important roles in regulating the activity of NER and BER enzymes in chromatin. Here, we will discuss the roles of different histone modifications and the corresponding modifying enzymes in DNA excision repair, highlighting the role of yeast as a model organism for many of these studies. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Base excision repair: a critical player in many games.

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    Wallace, Susan S

    2014-07-01

    This perspective reviews the many dimensions of base excision repair from a 10,000 foot vantage point and provides one person's view on where the field is headed. Enzyme function is considered under the lens of X-ray diffraction and single molecule studies. Base excision repair in chromatin and telomeres, regulation of expression and the role of posttranslational modifications are also discussed in the context of enzyme activities, cellular localization and interacting partners. The specialized roles that base excision repair play in transcriptional activation by active demethylation and targeted oxidation as well as how base excision repair functions in the immune processes of somatic hypermutation and class switch recombination and its possible involvement in retroviral infection are also discussed. Finally the complexities of oxidative damage and its repair and its link to neurodegenerative disorders, as well as the role of base excision repair as a tumor suppressor are examined in the context of damage, repair and aging. By outlining the many base excision repair-related mysteries that have yet to be unraveled, hopefully this perspective will stimulate further interest in the field. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Modulation of DNA base excision repair during neuronal differentiation

    DEFF Research Database (Denmark)

    Sykora, Peter; Yang, Jenq-Lin; Ferrarelli, Leslie K

    2013-01-01

    Neurons are terminally differentiated cells with a high rate of metabolism and multiple biological properties distinct from their undifferentiated precursors. Previous studies showed that nucleotide excision DNA repair is downregulated in postmitotic muscle cells and neurons. Here, we characterize...... DNA damage susceptibility and base excision DNA repair (BER) capacity in undifferentiated and differentiated human neural cells. The results show that undifferentiated human SH-SY5Y neuroblastoma cells are less sensitive to oxidative damage than their differentiated counterparts, in part because...

  3. True Lies: The Double Life of the Nucleotide Excision Repair Factors in Transcription and DNA Repair

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    Nicolas Le May

    2010-01-01

    Full Text Available Nucleotide excision repair (NER is a major DNA repair pathway in eukaryotic cells. NER removes structurally diverse lesions such as pyrimidine dimers, arising upon UV irradiation or bulky chemical adducts, arising upon exposure to carcinogens and some chemotherapeutic drugs. NER defects lead to three genetic disorders that result in predisposition to cancers, accelerated aging, neurological and developmental defects. During NER, more than 30 polypeptides cooperate to recognize, incise, and excise a damaged oligonucleotide from the genomic DNA. Recent papers reveal an additional and unexpected role for the NER factors. In the absence of a genotoxic attack, the promoters of RNA polymerases I- and II-dependent genes recruit XPA, XPC, XPG, and XPF to initiate gene expression. A model that includes the growth arrest and DNA damage 45α protein (Gadd45α and the NER factors, in order to maintain the promoter of active genes under a hypomethylated state, has been proposed but remains controversial. This paper focuses on the double life of the NER factors in DNA repair and transcription and describes the possible roles of these factors in the RNA synthesis process.

  4. Repairing Nanoparticle Surface Defects

    NARCIS (Netherlands)

    Marino, Emanuele; Kodger, Thomas E.; Crisp, R.W.; Timmerman, Dolf; MacArthur, Katherine E.; Heggen, Marc; Schall, Peter

    2017-01-01

    Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We

  5. Excision repair in mammalian cells. [uv radiation, N-acetoxy-2-acetylaminofluorene

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, F.E.; Setlow, R.B.

    1978-01-01

    Excision repair after combined treatments of uv and N-acetoxy-2-acetylaminofluorene (AAAF) was studied by three different techniques in cells proficient in uv excision repair and in cells deficient in uv repair. Two patterns of repair were observed: in repair proficient cells total repair was additive, and in repair deficient cells total repair was much less than additive--usually less than observed for separate treatments--and AAAF inhibited dimer excision. We conclude that in the 1st class of cells pathways for repair of uv and AAAF lesions are not identical, and in the 2nd class the residual excision enzymes are different from those in repair proficient cells.

  6. A Ubiquitin-Binding Domain in Cockayne Syndrome B Required for Transcription-Coupled Nucleotide Excision Repair

    NARCIS (Netherlands)

    R. Anindya (Roy); P.O. Mari (Pierre-Olivier); U. Kristensen (Ulrik); H.J.M. Kool (Hanneke); G. Giglia-Mari (Giuseppina); L.H.F. Mullenders (Leon); M.I. Fousteri (Maria); W. Vermeulen (Wim); J-M. Egly (Jean-Marc); J.Q. Svejstrup (Jesper)

    2010-01-01

    textabstractTranscription-coupled nucleotide excision repair (TC-NER) allows RNA polymerase II (RNAPII)-blocking lesions to be rapidly removed from the transcribed strand of active genes. Defective TCR in humans is associated with Cockayne syndrome (CS), typically caused by defects in either CSA or

  7. U. V. induces long-lived DNA breaks in Cockayne's syndrome and cells from an immunodeficient individual (46BR): defects and disturbance in post incision steps of excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Squires, S.; Johnson, R.T.

    1983-01-01

    In normal cells exposed to low U.V. doses the several enzymic steps of the excision repair process are closely coupled with the result that DNA gaps are transient and present at such low frequency that it is very difficult to detect them. Cells from a U.V.-sensitive human genetic disorder, Cockayne's Syndrome (CS) and from an immunodeficient individual 46BR, have been examined with respect to their incision capacity after U.V. in the presence and absence of inhibitors of DNA synthesis. We have measured the initial rates of DNA break accumulation in the presence of hydroxyurea and 1-beta-D arabinofuranosylcytosine and find that in both these groups the rate is only slightly lower than in normal cells. However, there is a marked difference between U.V. sensitive cells and normal in the accumulation of long-lived DNA breaks in the absence of inhibitors. While in normal cells practically no breaks could be detected, the U.V. sensitive cells accumulated significant numbers of DNA breaks within 15 min of incubation; 46BR cells showed almost the same level of DNA breaks without the inhibitors as with them. In CS break accumulation can be detected in the absence of inhibitors for only a short time after irradiation (approximately 30 min), but less so when deoxyribonucleosides are provided. The spontaneous break accumulation is related to the time elapsed since proteolytic detachment of the cells from monolayer; 24 h after replating CS breaks no longer accumulate in response to U.V. 46BR cells, on the other hand, accumulate breaks even 1 day after replating and express unligated gaps 2 h after irradiation with a relatively low U.V. dose such as 4 Jm-2. Provision of DNA precursors does not greatly reduce break accumulation. The extremely slow rate of gap sealing in 46BR cells is consistent with the hypothesis that a ligase defect is expressed in these cells.

  8. Molecular cloning of the human excision repair gene ERCC-6.

    NARCIS (Netherlands)

    C. Troelstra (Christine); H. Odijk (Hanny); J. de Wit (Jan); A. Westerveld (Andries); L.H. Thompson; D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1990-01-01

    textabstractThe UV-sensitive, nucleotide excision repair-deficient Chinese hamster mutant cell line UV61 was used to identify and clone a correcting human gene, ERCC-6. UV61, belonging to rodent complementation group 6, is only moderately UV sensitive in comparison with mutant lines in groups 1 to

  9. Histone displacement during nucleotide excision repair

    DEFF Research Database (Denmark)

    Dinant, C.; Bartek, J.; Bekker-Jensen, S.

    2012-01-01

    chromatin. The condensed nature of chromatin inhibits many DNA metabolizing activities, including NER. In order to promote efficient repair, detection of a lesion not only has to activate the NER pathway but also chromatin remodeling. In general, such remodeling is thought on the one hand to precede NER...... of histone variants and histone displacement (including nucleosome sliding). Here we review current knowledge, and speculate about current unknowns, regarding those chromatin remodeling activities that physically displace histones before, during and after NER....

  10. Conservation and Divergence in Nucleotide Excision Repair Lesion Recognition*

    Science.gov (United States)

    Wirth, Nicolas; Gross, Jonas; Roth, Heide M.; Buechner, Claudia N.; Kisker, Caroline; Tessmer, Ingrid

    2016-01-01

    Nucleotide excision repair is an important and highly conserved DNA repair mechanism with an exceptionally large range of chemically and structurally unrelated targets. Lesion verification is believed to be achieved by the helicases UvrB and XPD in the prokaryotic and eukaryotic processes, respectively. Using single molecule atomic force microscopy analyses, we demonstrate that UvrB and XPD are able to load onto DNA and pursue lesion verification in the absence of the initial lesion detection proteins. Interestingly, our studies show different lesion recognition strategies for the two functionally homologous helicases, as apparent from their distinct DNA strand preferences, which can be rationalized from the different structural features and interactions with other nucleotide excision repair protein factors of the two enzymes. PMID:27405761

  11. Chromatin Dynamics during Nucleotide Excision Repair: Histones on the Move

    Directory of Open Access Journals (Sweden)

    Sophie E. Polo

    2012-09-01

    Full Text Available It has been a long-standing question how DNA damage repair proceeds in a nuclear environment where DNA is packaged into chromatin. Several decades of analysis combining in vitro and in vivo studies in various model organisms ranging from yeast to human have markedly increased our understanding of the mechanisms underlying chromatin disorganization upon damage detection and re-assembly after repair. Here, we review the methods that have been developed over the years to delineate chromatin alterations in response to DNA damage by focusing on the well-characterized Nucleotide Excision Repair (NER pathway. We also highlight how these methods have provided key mechanistic insight into histone dynamics coupled to repair in mammals, raising new issues about the maintenance of chromatin integrity. In particular, we discuss how NER factors and central players in chromatin dynamics such as histone modifiers, nucleosome remodeling factors, and histone chaperones function to mobilize histones during repair.

  12. Chromatin Dynamics during Nucleotide Excision Repair: Histones on the Move

    Science.gov (United States)

    Adam, Salomé; Polo, Sophie E.

    2012-01-01

    It has been a long-standing question how DNA damage repair proceeds in a nuclear environment where DNA is packaged into chromatin. Several decades of analysis combining in vitro and in vivo studies in various model organisms ranging from yeast to human have markedly increased our understanding of the mechanisms underlying chromatin disorganization upon damage detection and re-assembly after repair. Here, we review the methods that have been developed over the years to delineate chromatin alterations in response to DNA damage by focusing on the well-characterized Nucleotide Excision Repair (NER) pathway. We also highlight how these methods have provided key mechanistic insight into histone dynamics coupled to repair in mammals, raising new issues about the maintenance of chromatin integrity. In particular, we discuss how NER factors and central players in chromatin dynamics such as histone modifiers, nucleosome remodeling factors, and histone chaperones function to mobilize histones during repair. PMID:23109890

  13. Xeroderma pigmentosum group F caused by a defect in a structure-specific DNA repair endonuclease.

    NARCIS (Netherlands)

    A.M. Sijbers (Anneke); W.L. de Laat (Wouter); R.A. Ariza (Rafael); M. Biggerstaff (Maureen); Y-F. Wei; J.G. Moggs (Jonathan); K.C. Carter (Kenneth); B.K. Shell (Brenda); E. Evans (Elizabeth); M.C. de Jong (Mariska); S. Rademakers (Suzanne); J.D. de Rooij (Johan); N.G.J. Jaspers (Nicolaas); J.H.J. Hoeijmakers (Jan); R.D. Wood (Richard)

    1996-01-01

    textabstractNucleotide excision repair, which is defective in xeroderma pigmentosum (XP), involves incision of a DNA strand on each side of a lesion. We isolated a human gene homologous to yeast Rad1 and found that it corrects the repair defects of XP group F as well as rodent groups 4 and 11.

  14. Excision and crosslink repair of DNA and sister chromatid exchanges in cultured human fibroblasts with different repair capacities

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Y.; Kano, Y.; Paul, P.; Goto, K.; Yamamoto, K. (Kobe Univ. (Japan). School of Medicine)

    1981-01-01

    Xeroderma pigmentosum (XP) groups A to G lacked the initial stage of ultraviolet (UV) excision repair in the order of A = G > C > D > E asymptotically equals F, while the XP variant was weakly defective in the later repair steps. Killing sensitivities were in the orders of A >= G > D > C > E asymptotically equals F asymptotically equals variant > normal to UV, A = G > D > F > C = E > variant > normal to 4-nitroquinoline-1-oxide (4NQO), and A > C > D = E = F = variant > G = normal to decarbamoyl mitomycin-C(DCMC). The induced sister chromatid exchange (SCE) frequency was unrelated to the extent of repair deficiency. The SCE induction rate was consistently 3 - 6 fold higher by these UV-like mutagens in XP group A cells than in normal cells. However, repair-proficient Cockayne's syndrome (CS) cells showed a higher SCE induction by UV, which was normalized by NAD/sup +/, suggesting that chromatin lesions as well as DNA damage contribute to SCE. Two-step crosslink repair involves a first rapid half-excision and a second slow nucleotide-excision repair. Fanconi's anemia (FA) cells had an impaired first half-excision and were supersensitive to MC, but not to UV and DCMC. The SCE frequency induced by MC (1 hr) was higher in FA cells than in normal cells despite their normal response to DCMC, and vice versa in XP cells. FA cells lacked the first rapid decline and showed higher remaining SCEs. Thus, part of the crosslink seems to lead to SCE formation. Caffeine synergistically elevated UV-induced SCEs, but not UV induced mutations in V79 cells, implying that SCE may not necessarily involve mutation.

  15. DNA base excision repair and nucleotide excision repair synergistically contribute to survival of stationary-phase cells of the fission yeast Schizosaccharomyces pombe.

    Science.gov (United States)

    Senoo, Takanori; Kawano, Shinji; Ikeda, Shogo

    2017-03-01

    Defects of genome maintenance may causally contribute to aging. In general, base excision repair (BER) is involved in the repair of subtle base lesions and AP sites, and bulky helix-distorting lesions are restored by nucleotide excision repair (NER). Here, we measured the chronological lifespan (CLS) of BER- and NER-deficient mutants of the fission yeast Schizosaccharomyces pombe, and observed the aging process of cells. The CLS of the nth1 (gene for DNA glycosylase/AP lyase) mutant and the rad16 (a homolog of human XPF) mutant were slightly shorter than that of the wild-type (WT) strain. However, survival of the nth1Δ rad16Δ double mutant was significantly reduced after entry into the stationary phase. Deletion of rad16 in an AP endonuclease mutant apn2Δ also accelerated chronological aging. These results indicate that BER and NER synergistically contribute to genome maintenance in non-dividing cells. Reactive oxygen species (ROS) accumulated in cells during the stationary phase, and nth1Δ rad16Δ cells produced more ROS than WT cells. High mutation frequencies and nuclear DNA fragmentation were observed in nth1Δ rad16Δ stationary-phase cells concurrent with apoptotic-like cell death. Calorie restriction significantly reduced the level of ROS in the stationary phase and extended the CLS of nth1Δ rad16Δ cells. Therefore, ROS production critically affects the survival of the DNA repair mutant during chronological aging. © 2017 International Federation for Cell Biology.

  16. 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.

  17. Dynamic control of strand excision during human DNA mismatch repair.

    Science.gov (United States)

    Jeon, Yongmoon; Kim, Daehyung; Martín-López, Juana V; Lee, Ryanggeun; Oh, Jungsic; Hanne, Jeungphill; Fishel, Richard; Lee, Jong-Bong

    2016-03-22

    Mismatch repair (MMR) is activated by evolutionarily conserved MutS homologs (MSH) and MutL homologs (MLH/PMS). MSH recognizes mismatched nucleotides and form extremely stable sliding clamps that may be bound by MLH/PMS to ultimately authorize strand-specific excision starting at a distant 3'- or 5'-DNA scission. The mechanical processes associated with a complete MMR reaction remain enigmatic. The purified human (Homo sapien or Hs) 5'-MMR excision reaction requires the HsMSH2-HsMSH6 heterodimer, the 5' → 3' exonuclease HsEXOI, and the single-stranded binding heterotrimer HsRPA. The HsMLH1-HsPMS2 heterodimer substantially influences 5'-MMR excision in cell extracts but is not required in the purified system. Using real-time single-molecule imaging, we show that HsRPA or Escherichia coli EcSSB restricts HsEXOI excision activity on nicked or gapped DNA. HsMSH2-HsMSH6 activates HsEXOI by overcoming HsRPA/EcSSB inhibition and exploits multiple dynamic sliding clamps to increase tract length. Conversely, HsMLH1-HsPMS2 regulates tract length by controlling the number of excision complexes, providing a link to 5' MMR.

  18. Radiation induced base excision repair (BER): a mechanistic mathematical approach.

    Science.gov (United States)

    Rahmanian, Shirin; Taleei, Reza; Nikjoo, Hooshang

    2014-10-01

    This paper presents a mechanistic model of base excision repair (BER) pathway for the repair of single-stand breaks (SSBs) and oxidized base lesions produced by ionizing radiation (IR). The model is based on law of mass action kinetics to translate the biochemical processes involved, step-by-step, in the BER pathway to translate into mathematical equations. The BER is divided into two subpathways, short-patch repair (SPR) and long-patch repair (LPR). SPR involves in replacement of single nucleotide via Pol β and ligation of the ends via XRCC1 and Ligase III, while LPR involves in replacement of multiple nucleotides via PCNA, Pol δ/ɛ and FEN 1, and ligation via Ligase I. A hallmark of IR is the production of closely spaced lesions within a turn of DNA helix (named complex lesions), which have been attributed to a slower repair process. The model presented considers fast and slow component of BER kinetics by assigning SPR for simple lesions and LPR for complex lesions. In the absence of in vivo reaction rate constants for the BER proteins, we have deduced a set of rate constants based on different published experimental measurements including accumulation kinetics obtained from UVA irradiation, overall SSB repair kinetic experiments, and overall BER kinetics from live-cell imaging experiments. The model was further used to calculate the repair kinetics of complex base lesions via the LPR subpathway and compared to foci kinetic experiments for cells irradiated with γ rays, Si, and Fe ions. The model calculation show good agreement with experimental measurements for both overall repair and repair of complex lesions. Furthermore, using the model we explored different mechanisms responsible for inhibition of repair when higher LET and HZE particles are used and concluded that increasing the damage complexity can inhibit initiation of LPR after the AP site removal step in BER. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Cloning, comparative mapping, and RNA expression of the mouse homologues of the Saccharomyces cerevisiae nucleotide excision repair gene RAD23.

    NARCIS (Netherlands)

    P.J. van der Spek (Peter); C.E. Visser (Cécile); F. Hanaoka (Fumio); B. Smit (Bep); A. Hagemeijer (Anne); D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1996-01-01

    textabstractThe Saccharomyces cerevisiae RAD23 gene is involved in nucleotide excision repair (NER). Two human homologs of RAD23, HHR23A and HHR23B (HGMW-approved symbols RAD23A and RAD23B), were previously isolated. The HHR23B protein is complexed with the protein defective in the cancer-prone

  20. A presumed DNA helicase, encoded by the excision repair gene ERCC-3 is involved in the human repair disorders xeroderma pigmentosum and Cockayne's syndrome.

    NARCIS (Netherlands)

    G. Weeda (Geert); R.C.A. van Ham; W. Vermeulen (Wim); D. Bootsma (Dirk); A.J. van der Eb; J.H.J. Hoeijmakers (Jan)

    1990-01-01

    textabstractThe human gene ERCC-3 specifically corrects the defect in an early step of the DNA excision repair pathway of UV-sensitive rodent mutants of complementation group 3. The predicted 782 animo acid ERCC-3 protein harbors putative nucleotide, chromatin, and helix-turn-helix DNA binding

  1. Structural and Functional Studies on Nucleotide Excision Repair From Recognition to Incision.

    Energy Technology Data Exchange (ETDEWEB)

    Caroline Kisker

    2001-01-01

    Maintenance of the correct genetic information is crucial for all living organisms because mutations are the primary cause of hereditary diseases, as well as cancer and may also be involved in aging. The importance of genomic integrity is underscored by the fact that 80 to 90% of all human cancers are ultimately due to DNA damage. Among the different repair mechanisms that have evolved to protect the genome, nucleotide excision repair (NER) is a universal pathway found in all organisms. NER removes a wide variety of bulky DNA adducts including the carcinogenic cyclobutane pyrimidine dimers induced by UV radiation, benzo(a)pyrene-guanine adducts caused by smoking and the guanine-cisplatin adducts induced by chemotherapy. The importance of this repair mechanism is reflected by three severe inherited diseases in humans, which are due to defects in NER: xeroderma pigmentosum, Cockayne's syndrome and trichothiodystrophy.

  2. Nucleotide excision repair- and p53-deficient mouse models in cancer research

    Energy Technology Data Exchange (ETDEWEB)

    Hoogervorst, Esther M. [Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands); Utrecht University, Department of Pathobiology, Utrecht (Netherlands); Steeg, Harry van [Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands); Vries, Annemieke de [Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands)]. E-mail: Annemieke.de.Vries@rivm.nl

    2005-07-01

    Cancer is caused by the loss of controlled cell growth due to mutational (in)activation of critical genes known to be involved in cell cycle regulation. Three main mechanisms are known to be involved in the prevention of cells from becoming cancerous; DNA repair and cell cycle control, important to remove DNA damage before it will be fixed into mutations and apoptosis, resulting in the elimination of cells containing severe DNA damage. Several human syndromes are known to have (partially) deficiencies in these pathways, and are therefore highly cancer prone. Examples are xeroderma pigmentosum (XP) caused by an inborn defect in the nucleotide excision repair (NER) pathway and the Li-Fraumeni syndrome, which is the result of a germ line mutation in the p53 gene. XP patients develop skin cancer on sun exposed areas at a relatively early age, whereas Li-Fraumeni patients spontaneously develop a wide variety of early onset tumors, including sarcomas, leukemia's and mammary gland carcinomas. Several mouse models have been generated to mimic these human syndromes, providing us information about the role of these particular gene defects in the tumorigenesis process. In this review, spontaneous phenotypes of mice deficient for nucleotide excision repair and/or the p53 gene will be described, together with their responses upon exposure to either chemical carcinogens or radiation. Furthermore, possible applications of these and newly generated mouse models for cancer will be given.

  3. SPT4 increases UV-induced mutagenesis in yeast through impaired nucleotide excision repair

    National Research Council Canada - National Science Library

    Kang, Mi-Sun; Yu, Sung-Lim; Kim, Ho-Yeol; Lim, Hyun-Sook; Lee, Sung-Keun

    2013-01-01

    .... As unrepaired DNA lesions inhibit transcription, UV-induced damage to transcribed DNA is repaired preferentially versus non-transcribed DNA through transcription-coupled nucleotide excision repair (TCR...

  4. Base Sequence Context Effects on Nucleotide Excision Repair

    Science.gov (United States)

    Cai, Yuqin; Patel, Dinshaw J.; Broyde, Suse; Geacintov, Nicholas E.

    2010-01-01

    Nucleotide excision repair (NER) plays a critical role in maintaining the integrity of the genome when damaged by bulky DNA lesions, since inefficient repair can cause mutations and human diseases notably cancer. The structural properties of DNA lesions that determine their relative susceptibilities to NER are therefore of great interest. As a model system, we have investigated the major mutagenic lesion derived from the environmental carcinogen benzo[a]pyrene (B[a]P), 10S (+)-trans-anti-B[a]P-N2-dG in six different sequence contexts that differ in how the lesion is positioned in relation to nearby guanine amino groups. We have obtained molecular structural data by NMR and MD simulations, bending properties from gel electrophoresis studies, and NER data obtained from human HeLa cell extracts for our six investigated sequence contexts. This model system suggests that disturbed Watson-Crick base pairing is a better recognition signal than a flexible bend, and that these can act in concert to provide an enhanced signal. Steric hinderance between the minor groove-aligned lesion and nearby guanine amino groups determines the exact nature of the disturbances. Both nearest neighbor and more distant neighbor sequence contexts have an impact. Regardless of the exact distortions, we hypothesize that they provide a local thermodynamic destabilization signal for repair. PMID:20871811

  5. Implication of Posttranslational Histone Modifications in Nucleotide Excision Repair

    Directory of Open Access Journals (Sweden)

    Shisheng Li

    2012-09-01

    Full Text Available Histones are highly alkaline proteins that package and order the DNA into chromatin in eukaryotic cells. Nucleotide excision repair (NER is a conserved multistep reaction that removes a wide range of generally bulky and/or helix-distorting DNA lesions. Although the core biochemical mechanism of NER is relatively well known, how cells detect and repair lesions in diverse chromatin environments is still under intensive research. As with all DNA-related processes, the NER machinery must deal with the presence of organized chromatin and the physical obstacles it presents. A huge catalogue of posttranslational histone modifications has been documented. Although a comprehensive understanding of most of these modifications is still lacking, they are believed to be important regulatory elements for many biological processes, including DNA replication and repair, transcription and cell cycle control. Some of these modifications, including acetylation, methylation, phosphorylation and ubiquitination on the four core histones (H2A, H2B, H3 and H4 or the histone H2A variant H2AX, have been found to be implicated in different stages of the NER process. This review will summarize our recent understanding in this area.

  6. DNA excision repair in cell extracts from human cell lines exhibiting hypersensitivity to DNA-damaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, J.; Keyse, S.M.; Lindahl, T.; Wood, R.D. (Imperial Cancer Research Fund, South Mimms, (United Kingdom))

    1991-07-01

    Whole cell extracts from human lymphoid cell lines can perform in vitro DNA repair synthesis in plasmids damaged by agents including UV or cis-diamminedichloroplatinum(II) (cis-DDP). Extracts from xeroderma pigmentosum (XP) cells are defective in repair synthesis. We have now studied in vitro DNA repair synthesis using extracts from lymphoblastoid cell lines representing four human hereditary syndromes with increased sensitivity to DNA-damaging agents. Extracts of cell lines from individuals with the sunlight-sensitive disorders dysplastic nevus syndrome or Cockayne's syndrome (complementation groups A and B) showed normal DNA repair synthesis in plasmids with UV photoproducts. This is consistent with in vivo measurements of the overall DNA repair capacity in such cell lines. A number of extracts were prepared from two cell lines representing the variant form of XP (XP-V). Half of the extracts prepared showed normal levels of in vitro DNA repair synthesis in plasmids containing UV lesions, but the remainder of the extracts from the same cell lines showed deficient repair synthesis, suggesting the possibility of an unusually labile excision repair protein in XP-V. Fanconi's anemia (FA) cells show cellular hypersensitivity to cross-linking agents including cis-DDP. Extracts from cell lines belonging to two different complementation groups of FA showed normal DNA repair synthesis in plasmids containing cis-DDP or UV adducts. Thus, there does not appear to be an overall excision repair defect in FA, but the data do not exclude a defect in the repair of interstrand DNA cross-links.

  7. The role of DNA base excision repair in brain homeostasis and disease

    DEFF Research Database (Denmark)

    Akbari, Mansour; Morevati, Marya; Croteau, Deborah

    2015-01-01

    of proteins required for BER or proteins that regulate BER have been consistently associated with neurological dysfunction and disease in humans. Recent studies suggest that DNA lesions in the nuclear and mitochondrial compartments and the cellular response to those lesions have a profound effect on cellular......Chemical modification and spontaneous loss of nucleotide bases from DNA are estimated to occur at the rate of thousands per human cell per day. DNA base excision repair (BER) is a critical mechanism for repairing such lesions in nuclear and mitochondrial DNA. Defective expression or function...... energy homeostasis, mitochondrial function and cellular bioenergetics, with especially strong influence on neurological function. Further studies in this area could lead to novel approaches to prevent and treat human neurodegenerative disease....

  8. 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

  9. Base excision repair dysfunction in a subgroup of patients with myelodysplastic syndrome.

    Science.gov (United States)

    Jankowska, A M; Gondek, L P; Szpurka, H; Nearman, Z P; Tiu, R V; Maciejewski, J P

    2008-03-01

    In myelodysplastic syndromes (MDS) increased chromosomal breaks point toward defects in DNA repair machinery including base excision repair (BER) pathway involved in handling of oxidative DNA damage. We investigated whether defects in this pathway can be found in MDS. Elevated levels of 8-oxoguanine (8-OG) were found in a significant proportion of MDS patients, indicating increased oxidative DNA damage or defective handling of oxidative load. In a distinct subgroup of patients, increased 8-OG content was associated with increased hOGG1 mRNA expression and activity. In some patients, increased numbers of abasic sites (AP sites) correlated with low levels of POLbeta. To further investigate the nature of this defect, we examined genetic lesions potentially explaining accumulation of 8-OG and AP sites. We genotyped a large cohort of MDS patients and found a correlation between increased oxidative damage and the presence of the hOGG1-Cys326 allele suggesting inadequate compensatory feedback. Overall, this hOGG1 variant was more frequent in MDS, particularly in advanced forms, as compared to controls. In summary, we demonstrated that BER dysfunction in some MDS patients may be responsible for the increased 8-OG incorporation and explains one aspect of the propensity to chromosomal breaks in MDS but other mechanisms may also be involved.

  10. Nucleotide excision repair and the 26S proteasome function together to promote trinucleotide repeat expansions.

    Science.gov (United States)

    Concannon, Claire; Lahue, Robert S

    2014-01-01

    Trinucleotide repeat (TNR) expansion underpins a number of inheritable neurological human disorders. Multiple mechanisms are thought to contribute to the expansion process. The incorrect processing of the repeat tract by DNA repair proteins can drive this mutation process forward, as expansions are suppressed following ablation of certain repair factors in mouse models and cell models of disease. Nucleotide excision repair (NER) is one repair pathway implicated in TNR instability, although most previous work focussed on TNR contractions, not expansions. Here we investigated the role of NER in modulating expansions of threshold-length (CTG·CAG) repeats in yeast. We show that both the global genome and transcription-coupled repair subpathways promote expansions of threshold-length TNRs. Furthermore, NER works with the 26S proteasome to drive expansions, based on analysis of double mutants defective in both pathways, and of Rad23, a protein involved in both NER and the shuttling of ubiquitinated proteins to the proteasome. This work provides the first evidence that both subpathways of NER can promote threshold-length TNR expansions and that NER interacts with the proteasome to drive expansions. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Regulation of nucleotide excision repair by nuclear lamin b1.

    Directory of Open Access Journals (Sweden)

    Veronika Butin-Israeli

    Full Text Available The nuclear lamins play important roles in the structural organization and function of the metazoan cell nucleus. Recent studies on B-type lamins identified a requirement for lamin B1 (LB1 in the regulation of cell proliferation in normal diploid cells. In order to further investigate the function of LB1 in proliferation, we disrupted its normal expression in U-2 OS human osteosarcoma and other tumor cell lines. Silencing LB1 expression induced G1 cell cycle arrest without significant apoptosis. The arrested cells are unable to mount a timely and effective response to DNA damage induced by UV irradiation. Several proteins involved in the detection and repair of UV damage by the nucleotide excision repair (NER pathway are down-regulated in LB1 silenced cells including DDB1, CSB and PCNA. We propose that LB1 regulates the DNA damage response to UV irradiation by modulating the expression of specific genes and activating persistent DNA damage signaling. Our findings are relevant to understanding the relationship between the loss of LB1 expression, DNA damage signaling, and replicative senescence.

  12. Repair of Oxidative DNA Damage and Cancer: Recent Progress in DNA Base Excision Repair

    OpenAIRE

    Scott, Timothy L.; Rangaswamy, Suganya; Wicker, Christina A.; Izumi, Tadahide

    2014-01-01

    Significance: Reactive oxygen species (ROS) are generated by exogenous and environmental genotoxins, but also arise from mitochondria as byproducts of respiration in the body. ROS generate DNA damage of which pathological consequence, including cancer is well established. Research efforts are intense to understand the mechanism of DNA base excision repair, the primary mechanism to protect cells from genotoxicity caused by ROS. Recent Advances: In addition to the notion that oxidative DNA dama...

  13. Exposure to low dose of gamma radiation enhances the excision repair in Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, K.; Verma, N.C. [Bhabha Atomic Research Centre, Mumbai (India)

    1998-08-01

    The effect of low doses of ionizing and nonionizing radiation on the radiation response of yeast Saccharomyces cerevisiae toward ionizing and nonionizing radiation was studied. The wild-type strain D273-10B on exposure to 54 Gy gamma radiation (resulting in about 10% cell killing) showed enhanced resistance to subsequent exposure to UV radiation. This induced UV resistance increased with the incubation time between the initial gamma radiation stress and the UV irradiation. Exposure to low doses of UV light on the other hand showed no change in gamma or UV radiation response of this strain. The strains carrying a mutation at rad52 behaved in a way similar to the wild type, but with slightly reduced induced response. In contrast to this, the rad3 mutants, defective in excision repair, showed no induced UV resistance. Removal of UV-induced pyrimidine dimers in wild-type yeast DNA after UV irradiation was examined by analyzing the sites recognized by UV endonuclease from Micrococcus luteus. The samples that were exposed to low doses of gamma radiation before UV irradiation were able to repair the pyrimidine dimers more efficiently than the samples in which low gamma irradiation was omitted. The nature of enhanced repair was studied by scoring the frequency of induced gene conversion and reverse mutation at trp and ilv loci respectively in strain D7, which showed similar enhanced UV resistance induced by low-dose gamma irradiation. The induced repair was found to be essentially error-free. These results suggest that irradiation of strain D273-10B with low doses of gamma radiation enhances its capability for excision repair of UV-induced pyrimidine dimers. (author)

  14. Mismatch repair defects in human carcinogenesis.

    Science.gov (United States)

    Eshleman, J R; Markowitz, S D

    1996-01-01

    Mismatch repair defects are carcinogenic. This conclusion comes some 80 years after the original description of a type of familial colorectal cancer in which mismatch repair defects are involved, and from decades of dedicated basic science research into fundamental mechanisms cells use to repair their DNA. Mismatch repair (MMR) was described first in bacteria, later in yeast and finally in higher eukaryotes. In bacteria, one of its roles is the rapid repair of replicative errors thereby providing the genome with a 100-1000-fold level of protection against mutation. It also guards the genome by preventing recombination between non-homologous regions of DNA. The information gained from bacteria suddenly became relevant to human neoplasia in 1993 when the RER phenotype of microsatellite instability was discovered in human cancers and was rapidly shown to be due to defects in mismatch repair. Evidence supporting the role of MMR defects in carcinogenesis comes from a variety of independent sources including: (i) theoretical considerations of the requirement for a mutator phenotype as a step in multistage carcinogenesis; (ii) discovering that MMR defects cause a 'mutator phenotype' destabilizing endogenous expressed genes including those integral to carcinogenesis; (iii) finding MMR defects in the germline of HNPCC kindred members; (iv) finding that such defects behave as classic tumor suppressor genes in both familial and sporadic colorectal cancers; (v) discovering that MMR 'knockout' mice have an increased incidence of tumors; and (vi) discovering that genetic complementation of MMR defective cells stabilizes the MMR deficiency-associated microsatellite instability. Models of carcinogenesis now must integrate the concepts of a MMR defect induced mutator phenotype (Loeb) with the concepts of multistep colon carcinogenesis (Fearon and Vogelstein) and clonal heterogeneity/selection (Nowell).

  15. Use of in vivo and in vitro assays for the characterization of mammalian excision repair and isolation of repair proteins.

    NARCIS (Netherlands)

    J.H.J. Hoeijmakers (Jan); A.P.M. Eker (André); R.D. Wood (Richard); P. Robins

    1990-01-01

    textabstractElucidation of the molecular mechanism of mammalian nucleotide excision repair requires the availability of purified proteins, DNA substrates with defined lesions and suitable repair assays. Repair assays introduced in recent years vary from testing individual steps and successions of

  16. Base excision repair imbalance in colorectal cancer has prognostic value and modulates response to chemotherapy

    Science.gov (United States)

    Leguisamo, Natalia M.; Gloria, Helena C.; Kalil, Antonio N.; Martins, Talita V.; Azambuja, Daniel B.

    2017-01-01

    Colorectal cancer (CRC) is prevalent worldwide, and treatment often involves surgery and genotoxic chemotherapy. DNA repair mechanisms, such as base excision repair (BER) and mismatch repair (MMR), may not only influence tumour characteristics and prognosis but also dictate chemotherapy response. Defective MMR contributes to chemoresistance in colorectal cancer. Moreover, BER affects cellular survival by repairing genotoxic base damage in a process that itself can disrupt metabolism. In this study, we characterized BER and MMR gene expression in colorectal tumours and the association between this repair profile with patients’ clinical and pathological features. In addition, we exploited the possible mechanisms underlying the association between altered DNA repair, metabolism and response to chemotherapy. Seventy pairs of sporadic colorectal tumour samples and adjacent non-tumour mucosal specimens were assessed for BER and MMR gene and protein expression and their association with pathological and clinical features. MMR-deficient colon cancer cells (HCT116) transiently overexpressing MPG or XRCC1 were treated with 5-FU or TMZ and evaluated for viability and metabolic intermediate levels. Increase in BER gene and protein expression is associated with more aggressive tumour features and poor pathological outcomes in CRC. However, tumours with reduced MMR gene expression also displayed low MPG, OGG1 and PARP1 expression. Imbalancing BER by overexpression of MPG, but not XRCC1, sensitises MMR-deficient colon cancer cells to 5-FU and TMZ and leads to ATP depletion and lactate accumulation. MPG overexpression alters DNA repair and metabolism and is a potential strategy to overcome 5-FU chemotherapeutic resistance in MMR-deficient CRC. PMID:28903334

  17. Polymorphism of the DNA Base Excision Repair Genes in Keratoconus

    Science.gov (United States)

    Wojcik, Katarzyna A.; Synowiec, Ewelina; Sobierajczyk, Katarzyna; Izdebska, Justyna; Blasiak, Janusz; Szaflik, Jerzy; Szaflik, Jacek P.

    2014-01-01

    Keratoconus (KC) is a degenerative corneal disorder for which the exact pathogenesis is not yet known. Oxidative stress is reported to be associated with this disease. The stress may damage corneal biomolecules, including DNA, and such damage is primarily removed by base excision repair (BER). Variation in genes encoding BER components may influence the effectiveness of corneal cells to cope with oxidative stress. In the present work we genotyped 5 polymorphisms of 4 BER genes in 284 patients and 353 controls. The A/A genotype of the c.–1370T>A polymorphism of the DNA polymerase γ (POLG) gene was associated with increased occurrence of KC, while the A/T genotype was associated with decreased occurrence of KC. The A/G genotype and the A allele of the c.1196A>G polymorphism of the X-ray repair cross-complementing group 1 (XRCC1) were associated with increased, and the G/G genotype and the G allele, with decreased KC occurrence. Also, the C/T and T as well as C/C genotypes and alleles of the c.580C>T polymorphism of the same gene displayed relationship with KC occurrence. Neither the g.46438521G>C polymorphism of the Nei endonuclease VIII-like 1 (NEIL1) nor the c.2285T>C polymorphism of the poly(ADP-ribose) polymerase-1 (PARP-1) was associated with KC. In conclusion, the variability of the XRCC1 and POLG genes may play a role in KC pathogenesis and determine the risk of this disease. PMID:25356504

  18. Polymorphism of the DNA Base Excision Repair Genes in Keratoconus

    Directory of Open Access Journals (Sweden)

    Katarzyna A. Wojcik

    2014-10-01

    Full Text Available Keratoconus (KC is a degenerative corneal disorder for which the exact pathogenesis is not yet known. Oxidative stress is reported to be associated with this disease. The stress may damage corneal biomolecules, including DNA, and such damage is primarily removed by base excision repair (BER. Variation in genes encoding BER components may influence the effectiveness of corneal cells to cope with oxidative stress. In the present work we genotyped 5 polymorphisms of 4 BER genes in 284 patients and 353 controls. The A/A genotype of the c.–1370T>A polymorphism of the DNA polymerase γ (POLG gene was associated with increased occurrence of KC, while the A/T genotype was associated with decreased occurrence of KC. The A/G genotype and the A allele of the c.1196A>G polymorphism of the X-ray repair cross-complementing group 1 (XRCC1 were associated with increased, and the G/G genotype and the G allele, with decreased KC occurrence. Also, the C/T and T as well as C/C genotypes and alleles of the c.580C>T polymorphism of the same gene displayed relationship with KC occurrence. Neither the g.46438521G>C polymorphism of the Nei endonuclease VIII-like 1 (NEIL1 nor the c.2285T>C polymorphism of the poly(ADP-ribose polymerase-1 (PARP-1 was associated with KC. In conclusion, the variability of the XRCC1 and POLG genes may play a role in KC pathogenesis and determine the risk of this disease.

  19. The role of Cockayne syndrome group A (CSA) protein in transcription-coupled nucleotide excision repair.

    Science.gov (United States)

    Saijo, Masafumi

    2013-01-01

    Nucleotide excision repair (NER) removes a variety of DNA lesions, including ultraviolet-induced cyclobutane pyrimidine dimers. NER comprises two subpathways: transcription-coupled NER (TC-NER) and global genome NER. TC-NER efficiently removes lesions from the transcribed strands of active genes. Mutations in Cockayne syndrome groups A and B genes (CSA and CSB) result in defective TC-NER. In mammalian cells, TC-NER is presumably initiated by the arrest of RNA polymerase II at a lesion on the transcribed strand of an active gene, but the molecular mechanism underlying TC-NER remains unclear. The CSA protein has seven WD40 repeat motifs and beta-propeller architecture. A protein complex consisting of CSA, DDB1, cullin 4A, and Roc1 exhibits ubiquitin ligase activity. The role of CSA protein in TC-NER is described in this review. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. Gastroesophageal junction adenocarcinoma displays abnormalities in homologous recombination and nucleotide excision repair

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    Dewalt RI

    2014-02-01

    Full Text Available Robin I Dewalt,1 Kenneth A Kesler,2 Zane T Hammoud,3 LeeAnn Baldridge,4 Eyas M Hattab,4 Shadia I Jalal1,5 1Division of Hematology/Oncology, Department of Medicine, 2Cardiothoracic Division, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA; 3Henry Ford Hospital, Detroit, MI, USA; 4Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; 5Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, USA Objective: Esophageal adenocarcinoma (EAC continues to be a disease associated with high mortality. Among the factors leading to poor outcomes are innate resistance to currently available therapies, advanced stage at diagnosis, and complex biology. Platinum and ionizing radiation form the backbone of treatment for the majority of patients with EAC. Of the multiple processes involved in response to platinum chemotherapy or ionizing radiation, deoxyribonucleic acid (DNA repair has been a major player in cancer sensitivity to these agents. DNA repair defects have been described in various malignancies. The purpose of this study was to determine whether alterations in DNA repair are present in EAC compared with normal gastroesophageal tissues. Methods: We analyzed the expression of genes involved in homologous recombination (HR, nonhomologous end-joining, and nucleotide excision repair (NER pathways in 12 EAC tumor samples with their matched normal counterparts. These pathways were chosen because they are the main pathways involved in the repair of platinum- or ionizing-radiation-induced damage. In addition, abnormalities in these pathways have not been well characterized in EAC. Results: We identified increased expression of at least one HR gene in eight of the EAC tumor samples. Alterations in the expression of EME1, a structure-specific endonuclease involved in HR, were the most prevalent, with messenger (mRNA overexpression in six of the EAC samples

  1. Mismatch repair and nucleotide excision repair proteins cooperate in the recognition of DNA interstrand crosslinks

    Science.gov (United States)

    Zhao, Junhua; Jain, Aklank; Iyer, Ravi R.; Modrich, Paul L.; Vasquez, Karen M.

    2009-01-01

    DNA interstrand crosslinks (ICLs) are among the most cytotoxic types of DNA damage, thus ICL-inducing agents such as psoralen, are clinically useful chemotherapeutics. Psoralen-modified triplex-forming oligonucleotides (TFOs) have been used to target ICLs to specific genomic sites to increase the selectivity of these agents. However, how TFO-directed psoralen ICLs (Tdp-ICLs) are recognized and processed in human cells is unclear. Previously, we reported that two essential nucleotide excision repair (NER) protein complexes, XPA–RPA and XPC–RAD23B, recognized ICLs in vitro, and that cells deficient in the DNA mismatch repair (MMR) complex MutSβ were sensitive to psoralen ICLs. To further investigate the role of MutSβ in ICL repair and the potential interaction between proteins from the MMR and NER pathways on these lesions, we performed electrophoretic mobility-shift assays and chromatin immunoprecipitation analysis of MutSβ and NER proteins with Tdp-ICLs. We found that MutSβ bound to Tdp-ICLs with high affinity and specificity in vitro and in vivo, and that MutSβ interacted with XPA–RPA or XPC–RAD23B in recognizing Tdp-ICLs. These data suggest that proteins from the MMR and NER pathways interact in the recognition of ICLs, and provide a mechanistic link by which proteins from multiple repair pathways contribute to ICL repair. PMID:19468048

  2. Repair of oxidative DNA damage and cancer: recent progress in DNA base excision repair.

    Science.gov (United States)

    Scott, Timothy L; Rangaswamy, Suganya; Wicker, Christina A; Izumi, Tadahide

    2014-02-01

    Reactive oxygen species (ROS) are generated by exogenous and environmental genotoxins, but also arise from mitochondria as byproducts of respiration in the body. ROS generate DNA damage of which pathological consequence, including cancer is well established. Research efforts are intense to understand the mechanism of DNA base excision repair, the primary mechanism to protect cells from genotoxicity caused by ROS. In addition to the notion that oxidative DNA damage causes transformation of cells, recent studies have revealed how the mitochondrial deficiencies and ROS generation alter cell growth during the cancer transformation. The emphasis of this review is to highlight the importance of the cellular response to oxidative DNA damage during carcinogenesis. Oxidative DNA damage, including 7,8-dihydro-8-oxoguanine, play an important role during the cellular transformation. It is also becoming apparent that the unusual activity and subcellular distribution of apurinic/apyrimidinic endonuclease 1, an essential DNA repair factor/redox sensor, affect cancer malignancy by increasing cellular resistance to oxidative stress and by positively influencing cell proliferation. Technological advancement in cancer cell biology and genetics has enabled us to monitor the detailed DNA repair activities in the microenvironment. Precise understanding of the intracellular activities of DNA repair proteins for oxidative DNA damage should provide help in understanding how mitochondria, ROS, DNA damage, and repair influence cancer transformation.

  3. Excision repair of bulky lesions in the DNA of mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Setlow, R B; Grist, E

    1980-01-01

    The report examines the process of excision repair of pyrimidine dimers from uv-irradiated and chemically challenged human cells. It is shown by means of a sensitive endonuclease assay that the amount of excision observed depends upon the isotope used to label cells, and that XP heterozygotes are between normals and XPs. (ACR)

  4. Age-Related Neuronal Degeneration: Complementary Roles of Nucleotide Excision Repair and Transcription-Coupled Repair in Preventing Neuropathology

    Science.gov (United States)

    de Waard, Monique C.; Haasdijk, Elize D.; Brandt, Renata; Vermeij, Marcel; Rijksen, Yvonne; Maas, Alex; van Steeg, Harry; Hoeijmakers, Jan H. J.; van der Horst, Gijsbertus T. J.

    2011-01-01

    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 XpdXPCS 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

  5. Periodontal plastic procedure for the management of the residual gingival defect after excision of an epulis

    Directory of Open Access Journals (Sweden)

    Varun Choudhary

    2015-01-01

    Full Text Available Dentinal hypersensitivity and unesthetic appearance are common findings after excision of an epulis due to exposure of root and underlying bone. The simultaneous placement of subepithelial connective tissue grafting after excision of the lesion seems to be viable surgical option in such cases. Furthermore, this will avoid second surgical procedure for the management of the residual gingival defect.

  6. Cloning and characterization of the human DNA-excision repair gene ERCC-1

    NARCIS (Netherlands)

    M. van Duin (Michel)

    1988-01-01

    textabstractIt is the aim of the work described in this thesis to isolate and characterize human genes involved DNA excision repair. This will facilitate the understanding of the mechanism of this repair process whereas it also provides an important step to better understand the relationship

  7. Mutational analysis of the human nucleotide excision repair gene ERCC1.

    NARCIS (Netherlands)

    A.M. Sijbers (Anneke); P.J. van der Spek (Peter); H. Odijk (Hanny); J.H. van den Berg (Jan); M. van Duin (Mark); A. Westerveld (Andries); N.G.J. Jaspers (Nicolaas); D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1996-01-01

    textabstractThe human DNA repair protein ERCC1 resides in a complex together with the ERCC4, ERCC11 and XP-F correcting activities, thought to perform the 5' strand incision during nucleotide excision repair (NER). Its yeast counterpart, RAD1-RAD10, has an additional engagement in a mitotic

  8. Usefulness of V-Y Advancement Flap for Defects after Skin Tumor Excision

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    Ki Hyun Kwon

    2012-11-01

    Full Text Available BackgroundAfter skin tumor excision on the face, extremities, or trunk, the choice of treatment for a skin defect is highly variable. Many surgeons prefer to use a local flap rather than a skin graft or free flap for small- or moderately-sized circular defects. We have used unilateral or bilateral V-Y advancement flaps, especially on the face. Here we evaluated the functional and aesthetic results of this technique.MethodsAll of the patients were pathologically diagnosed with squamous cell carcinoma (SCC, basal cell carcinoma (BCC, or malignant melanoma or premalignant lesion (Bowen's disease. Thirty-two patients underwent V-Y advancement flap repair (11 unilateral and 21 bilateral from January 2007 to June 2011. We analyzed the patients' age and satisfaction, and location and size of defect. The patients were followed up for 6 months or more.ResultsThere were 22 women and 10 men. The ages ranged from 47 to 93 years with a mean age of 66 years. The causes were SCC in 15 cases, BCC in 13 cases, malignant melanoma in 1 case, Bowen's disease in 2 cases, and another cause in 1 case. The tumor locations were the face in 28 patients, and the scalp, upper limb, and flank each in one patient. All of the flaps survived and the aesthetic results were good. Postoperative recovery was usually rapid, and no complication or tumor recurrence was observed.ConclusionsThe V-Y advancement flap is often used not only for facial circular defects but also for defects of the trunk and extremities. Its advantages are less scarring and superior aesthetic results as compared with other local flap methods, because of less scarification of adjacent tissue and because it is an easy surgical technique.

  9. Cockayne syndrome: defective repair of transcription?

    Science.gov (United States)

    van Gool, A J; van der Horst, G T; Citterio, E; Hoeijmakers, J H

    1997-07-16

    In the past years, it has become increasingly evident that basal metabolic processes within the cell are intimately linked and influenced by one another. One such link that recently has attracted much attention is the close interplay between nucleotide excision DNA repair and transcription. This is illustrated both by the preferential repair of the transcribed strand of active genes (a phenomenon known as transcription-coupled repair, TCR) as well as by the distinct dual involvement of proteins in both processes. The mechanism of TCR in eukaryotes is still largely unknown. It was first discovered in mammals by the pioneering studies of Hanawalt and colleagues, and subsequently identified in yeast and Escherichia coli. In the latter case, one protein, the transcription repair-coupling factor, was found to accomplish this function in vitro, and a plausible model for its activity was proposed. While the E. coli model still functions as a paradigm for TCR in eukaryotes, recent observations prompt us to believe that the situation in eukaryotes is much more complex, involving dual functionality of multiple proteins.

  10. Nuclear translocation contributes to regulation of DNA excision repair activities

    DEFF Research Database (Denmark)

    Knudsen, Nina Østergaard; Andersen, Sofie Dabros; Lützen, Anne

    2009-01-01

    .T. Tomicic, W.P. Roos, B. Kaina, Mechanisms of human DNA repair: an update, Toxicology 193 (2003) 3-34; N.B. Larsen, M. Rasmussen, L.J. Rasmussen, Nuclear and mitochondrial DNA repair: similar pathways? Mitochondrion 5 (2005) 89-108]. Protein interactions are not only important for function, but also...

  11. POLB: A new role of DNA polymerase beta in mitochondrial base excision repair.

    Science.gov (United States)

    Kaufman, Brett A; Van Houten, Bennett

    2017-12-01

    The mitochondrial genome is a matrilineally inherited DNA that encodes numerous essential subunits of the respiratory chain in all metazoans. As such mitochondrial DNA (mtDNA) sequence integrity is vital to organismal survival, but it has a limited cadre of DNA repair activities, primarily base excision repair (BER). We have known that the mtDNA is significantly oxidized by both endogenous and exogenous sources, but this does not lead to the expected preferential formation of transversion mutations, which suggest a robust base excision repair (BER) system. This year, two different groups reported compelling evidence that what was believed to be exclusively nuclear DNA repair polymerase, POLB, is located in the mitochondria and plays a significant role in mitochondrial BER, mtDNA integrity and mitochondrial function. In this commentary, we review the findings and highlight remaining questions for the field. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. DNA Repair Defects and Chromosomal Aberrations

    Science.gov (United States)

    Hada, Megumi; George, K. A.; Huff, J. L.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Yields of chromosome aberrations were assessed in cells deficient in DNA doublestrand break (DSB) repair, after exposure to acute or to low-dose-rate (0.018 Gy/hr) gamma rays or acute high LET iron nuclei. We studied several cell lines including fibroblasts deficient in ATM (ataxia telangiectasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. Chromosomes were analyzed using the fluorescence in situ hybridization (FISH) chromosome painting method in cells at the first division post irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma irradiation induced greater yields of both simple and complex exchanges in the DSB repair-defective cells than in the normal cells. The quadratic dose-response terms for both simple and complex chromosome exchanges were significantly higher for the ATM- and NBS-deficient lines than for normal fibroblasts. However, in the NBS cells the linear dose-response term was significantly higher only for simple exchanges. The large increases in the quadratic dose-response terms in these repair-defective cell lines points the importance of the functions of ATM and NBS in chromatin modifications to facilitate correct DSB repair and minimize the formation of aberrations. The differences found between ATM- and NBS-deficient cells at low doses suggest that important questions should with regard to applying observations of radiation sensitivity at high dose to low-dose exposures. For aberrations induced by iron nuclei, regression models preferred purely linear dose responses for simple exchanges and quadratic dose responses for complex exchanges. Relative biological effectiveness (RBE) factors of all of

  13. Polynucleotide kinase/phosphatase, Pnk1, is involved in base excision repair in Schizosaccharomyces pombe.

    Science.gov (United States)

    Kashkina, Ekaterina; Qi, Tao; Weinfeld, Michael; Young, Dallan

    2012-08-01

    We previously reported that Schizosaccharomyces pombe pnk1 cells are more sensitive than wild-type cells to γ-radiation and camptothecin, indicating that Pnk1 is required for DNA repair. Here, we report that pnk1pku70 and pnk1rhp51 double mutants are more sensitive to γ-radiation than single mutants, from which we infer that Pnk1's primary role is independent of either homologous recombination or non-homologous end joining mechanisms. We also report that pnk1 cells are more sensitive than wild-type cells to oxidizing and alkylating agents, suggesting that Pnk1 is involved in base excision repair. Mutational analysis of Pnk1 revealed that the DNA 3'-phosphatase activity is necessary for repair of DNA damage, whereas the 5'-kinase activity is dispensable. A role for Pnk1 in base excision repair is supported by genetic analyses which revealed that pnk1apn2 is synthetically lethal, suggesting that Pnk1 and Apn2 may function in parallel pathways essential for the repair of endogenous DNA damage. Furthermore, the nth1pnk1apn2 and tdp1pnk1apn2 triple mutants are viable, implying that single-strand breaks with 3'-blocked termini produced by Nth1 and Tdp1 contribute to synthetic lethality. We also examined the sensitivity to methyl methanesulfonate of all single and double mutant combinations of nth1, apn2, tdp1 and pnk1. Together, our results support a model where Tdp1 and Pnk1 act in concert in an Apn2-independent base excision repair pathway to repair 3'-blocked termini produced by Nth1; and they also provide evidence that Pnk1 has additional roles in base excision repair. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Understanding photodermatoses associated with defective DNA repair: Photosensitive syndromes without associated cancer predisposition.

    Science.gov (United States)

    Yew, Yik Weng; Giordano, Cerrene N; Spivak, Graciela; Lim, Henry W

    2016-11-01

    Photodermatoses associated with defective DNA repair are a group of photosensitive hereditary skin disorders. In this review, we focus on diseases and syndromes with defective nucleotide excision repair that are not accompanied by an increased risk of cutaneous malignancies despite having photosensitivity. Specifically, the gene mutations and transcription defects, epidemiology, and clinical features of Cockayne syndrome, cerebro-oculo-facial-skeletal syndrome, ultraviolet-sensitive syndrome, and trichothiodystrophy will be discussed. These conditions may also have other extracutaneous involvement affecting the neurologic system and growth and development. Rigorous photoprotection remains an important component of the management of these inherited DNA repair-deficiency photodermatoses. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  15. Genome Instability in Development and Aging: Insights from Nucleotide Excision Repair in Humans, Mice, and Worms

    Directory of Open Access Journals (Sweden)

    Diletta Edifizi

    2015-08-01

    Full Text Available DNA damage causally contributes to aging and cancer. Congenital defects in nucleotide excision repair (NER lead to distinct cancer-prone and premature aging syndromes. The genetics of NER mutations have provided important insights into the distinct consequences of genome instability. Recent work in mice and C. elegans has shed new light on the mechanisms through which developing and aging animals respond to persistent DNA damage. The various NER mouse mutants have served as important disease models for Xeroderma pigmentosum (XP, Cockayne syndrome (CS, and trichothiodystrophy (TTD, while the traceable genetics of C. elegans have allowed the mechanistic delineation of the distinct outcomes of genome instability in metazoan development and aging. Intriguingly, highly conserved longevity assurance mechanisms respond to transcription-blocking DNA lesions in mammals as well as in worms and counteract the detrimental consequences of persistent DNA damage. The insulin-like growth factor signaling (IIS effector transcription factor DAF-16 could indeed overcome DNA damage-driven developmental growth delay and functional deterioration even when DNA damage persists. Longevity assurance mechanisms might thus delay DNA damage-driven aging by raising the threshold when accumulating DNA damage becomes detrimental for physiological tissue functioning.

  16. Genome Instability in Development and Aging: Insights from Nucleotide Excision Repair in Humans, Mice, and Worms.

    Science.gov (United States)

    Edifizi, Diletta; Schumacher, Björn

    2015-08-13

    DNA damage causally contributes to aging and cancer. Congenital defects in nucleotide excision repair (NER) lead to distinct cancer-prone and premature aging syndromes. The genetics of NER mutations have provided important insights into the distinct consequences of genome instability. Recent work in mice and C. elegans has shed new light on the mechanisms through which developing and aging animals respond to persistent DNA damage. The various NER mouse mutants have served as important disease models for Xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD), while the traceable genetics of C. elegans have allowed the mechanistic delineation of the distinct outcomes of genome instability in metazoan development and aging. Intriguingly, highly conserved longevity assurance mechanisms respond to transcription-blocking DNA lesions in mammals as well as in worms and counteract the detrimental consequences of persistent DNA damage. The insulin-like growth factor signaling (IIS) effector transcription factor DAF-16 could indeed overcome DNA damage-driven developmental growth delay and functional deterioration even when DNA damage persists. Longevity assurance mechanisms might thus delay DNA damage-driven aging by raising the threshold when accumulating DNA damage becomes detrimental for physiological tissue functioning.

  17. Localization of the nucleotide excision repair gene ERCC-6 to human chromosome 10q11-q21.

    NARCIS (Netherlands)

    C. Troelstra (Christine); R.M. Landsvater; J. Wiegant; M. van der Ploeg; G. Viel; C.H.C.M. Buys; J.H.J. Hoeijmakers (Jan)

    1992-01-01

    textabstractWe have cloned the human DNA excision repair gene ERCC6 by virtue of its ability to correct the uv sensitivity of Chinese hamster overy cell mutant UV61. This mutant is a member of complementation group 6 of the nucleotide excision repair-deficient rodent mutants. By means of in situ

  18. Nucleotide excision repair I: from E.coli to yeast.

    NARCIS (Netherlands)

    J.H.J. Hoeijmakers (Jan)

    1993-01-01

    textabstractGenetic information is constantly deteriorating, mainly as a consequence of the action of numerous genotoxic agents. In order to cope with this fundamental problem, all living organisms have acquired a complex network of DNA repair systems to safeguard their genetic integrity. Nucleotide

  19. Small margin (2 mm) excision of peri-ocular basal cell carcinoma with delayed repair.

    Science.gov (United States)

    David, D B.; Gimblett, M L.; Potts, M J.; Harrad, R A.

    1999-03-01

    Successful surgical treatment of peri-ocular basal cell carcinomas requires complete excision. Mohs' micrographic surgery achieves this, but is not readily available in all hospitals. The standard 3-4 mm margin does not guarantee complete excision and histology is often not available until after a repair has been undertaken. The 3-4 mm margin has evolved to deal with all forms of BCC. In our opinion, this margin is unnecessarily large for nodular/ulcerative BCC. We report our interim results of excision of localised BCCs using a 2 mm margin in conjunction with a delayed repair following confirmation of histological clearance. Thirty-one patients were treated in this manner; there have been no recurrences after an average follow-up period of 36 months (range 24-57 months).

  20. Base excision repair deficient mice lacking the Aag alkyladenine DNA glycosylase.

    NARCIS (Netherlands)

    B.P. Engelward (Bevin); G. Weeda (Geert); M.D. Wyatt; J.L.M. Broekhof (Jose'); J. de Wit (Jan); I. Donker (Ingrid); J.M. Allan (James); B. Gold (Bert); J.H.J. Hoeijmakers (Jan); L.D. Samson (Leona)

    1997-01-01

    textabstract3-methyladenine (3MeA) DNA glycosylases remove 3MeAs from alkylated DNA to initiate the base excision repair pathway. Here we report the generation of mice deficient in the 3MeA DNA glycosylase encoded by the Aag (Mpg) gene. Alkyladenine DNA glycosylase turns out to be the major DNA

  1. Single-molecule fluorescence microscopy on nucleotide excision repair complexes using GFP fusion proteins

    NARCIS (Netherlands)

    Segers-Nolten, Gezina M.J.; Rademakers, Suzanne; Vermeulen, Wim; Lenferink, Aufrid T.M.; Otto, Cornelis; Hoeijmakers, Jan; Greve, Jan; Koenig, Karsten; Tanke, Hans J.; Schneckenburger, Herbert

    2000-01-01

    Scanning Confocal Fluorescence Microscopy is used for single molecule studies on DNA-protein complexes that occur in Nucleotide Excision Repair (NER). During DNA-damage elimination by the NER-pathway, complex protein structures assemble over DNA. It is our aim to resolve the architecture of these

  2. The mitochondrial transcription factor A functions in mitochondrial base excision repair

    DEFF Research Database (Denmark)

    Canugovi, Chandrika; Maynard, Scott; Bayne, Anne-Cécile V

    2010-01-01

    Mitochondrial transcription factor A (TFAM) is an essential component of mitochondrial nucleoids. TFAM plays an important role in mitochondrial transcription and replication. TFAM has been previously reported to inhibit nucleotide excision repair (NER) in vitro but NER has not yet been detected i...

  3. Uncommon nucleotide excision repair phenotypes revealed by targeted high-throughput sequencing.

    Science.gov (United States)

    Calmels, Nadège; Greff, Géraldine; Obringer, Cathy; Kempf, Nadine; Gasnier, Claire; Tarabeux, Julien; Miguet, Marguerite; Baujat, Geneviève; Bessis, Didier; Bretones, Patricia; Cavau, Anne; Digeon, Béatrice; Doco-Fenzy, Martine; Doray, Bérénice; Feillet, François; Gardeazabal, Jesus; Gener, Blanca; Julia, Sophie; Llano-Rivas, Isabel; Mazur, Artur; Michot, Caroline; Renaldo-Robin, Florence; Rossi, Massimiliano; Sabouraud, Pascal; Keren, Boris; Depienne, Christel; Muller, Jean; Mandel, Jean-Louis; Laugel, Vincent

    2016-03-22

    Deficient nucleotide excision repair (NER) activity causes a variety of autosomal recessive diseases including xeroderma pigmentosum (XP) a disorder which pre-disposes to skin cancer, and the severe multisystem condition known as Cockayne syndrome (CS). In view of the clinical overlap between NER-related disorders, as well as the existence of multiple phenotypes and the numerous genes involved, we developed a new diagnostic approach based on the enrichment of 16 NER-related genes by multiplex amplification coupled with next-generation sequencing (NGS). Our test cohort consisted of 11 DNA samples, all with known mutations and/or non pathogenic SNPs in two of the tested genes. We then used the same technique to analyse samples from a prospective cohort of 40 patients. Multiplex amplification and sequencing were performed using AmpliSeq protocol on the Ion Torrent PGM (Life Technologies). We identified causative mutations in 17 out of the 40 patients (43%). Four patients showed biallelic mutations in the ERCC6(CSB) gene, five in the ERCC8(CSA) gene: most of them had classical CS features but some had very mild and incomplete phenotypes. A small cohort of 4 unrelated classic XP patients from the Basque country (Northern Spain) revealed a common splicing mutation in POLH (XP-variant), demonstrating a new founder effect in this population. Interestingly, our results also found ERCC2(XPD), ERCC3(XPB) or ERCC5(XPG) mutations in two cases of UV-sensitive syndrome and in two cases with mixed XP/CS phenotypes. Our study confirms that NGS is an efficient technique for the analysis of NER-related disorders on a molecular level. It is particularly useful for phenotypes with combined features or unusually mild symptoms. Targeted NGS used in conjunction with DNA repair functional tests and precise clinical evaluation permits rapid and cost-effective diagnosis in patients with NER-defects.

  4. Low-Dose Formaldehyde Delays DNA Damage Recognition and DNA Excision Repair in Human Cells

    Science.gov (United States)

    Luch, Andreas; Frey, Flurina C. Clement; Meier, Regula; Fei, Jia; Naegeli, Hanspeter

    2014-01-01

    Objective Formaldehyde is still widely employed as a universal crosslinking agent, preservative and disinfectant, despite its proven carcinogenicity in occupationally exposed workers. Therefore, it is of paramount importance to understand the possible impact of low-dose formaldehyde exposures in the general population. Due to the concomitant occurrence of multiple indoor and outdoor toxicants, we tested how formaldehyde, at micromolar concentrations, interferes with general DNA damage recognition and excision processes that remove some of the most frequently inflicted DNA lesions. Methodology/Principal Findings The overall mobility of the DNA damage sensors UV-DDB (ultraviolet-damaged DNA-binding) and XPC (xeroderma pigmentosum group C) was analyzed by assessing real-time protein dynamics in the nucleus of cultured human cells exposed to non-cytotoxic (formaldehyde concentrations. The DNA lesion-specific recruitment of these damage sensors was tested by monitoring their accumulation at local irradiation spots. DNA repair activity was determined in host-cell reactivation assays and, more directly, by measuring the excision of DNA lesions from chromosomes. Taken together, these assays demonstrated that formaldehyde obstructs the rapid nuclear trafficking of DNA damage sensors and, consequently, slows down their relocation to DNA damage sites thus delaying the excision repair of target lesions. A concentration-dependent effect relationship established a threshold concentration of as low as 25 micromolar for the inhibition of DNA excision repair. Conclusions/Significance A main implication of the retarded repair activity is that low-dose formaldehyde may exert an adjuvant role in carcinogenesis by impeding the excision of multiple mutagenic base lesions. In view of this generally disruptive effect on DNA repair, we propose that formaldehyde exposures in the general population should be further decreased to help reducing cancer risks. PMID:24722772

  5. The hepatitis B virus x protein inhibits thymine DNA glycosylase initiated base excision repair.

    Directory of Open Access Journals (Sweden)

    Maarten A A van de Klundert

    Full Text Available The hepatitis B virus (HBV genome encodes the X protein (HBx, a ubiquitous transactivator that is required for HBV replication. Expression of the HBx protein has been associated with the development of HBV infection-related hepatocellular carcinoma (HCC. Previously, we generated a 3D structure of HBx by combined homology and ab initio in silico modelling. This structure showed a striking similarity to the human thymine DNA glycosylase (TDG, a key enzyme in the base excision repair (BER pathway. To further explore this finding, we investigated whether both proteins interfere with or complement each other's functions. Here we show that TDG does not affect HBV replication, but that HBx strongly inhibits TDG-initiated base excision repair (BER, a major DNA repair pathway. Inhibition of the BER pathway may contribute substantially to the oncogenic effect of HBV infection.

  6. The endoperoxide ascaridol shows strong differential cytotoxicity in nucleotide excision repair-deficient cells

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Rashda [Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Efferth, Thomas [Institute of Pharmacy und Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz (Germany); Kuhmann, Christine [Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Opatz, Till [Institute of Organic Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz (Germany); Hao, Xiaojiang [Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204 (China); Popanda, Odilia, E-mail: o.popanda@dkfz.de [Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Schmezer, Peter [Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

    2012-03-15

    Targeting synthetic lethality in DNA repair pathways has become a promising anti-cancer strategy. However little is known about such interactions with regard to the nucleotide excision repair (NER) pathway. Therefore, cell lines with a defect in the NER genes ERCC6 or XPC and their normal counterparts were screened with 53 chemically defined phytochemicals isolated from plants used in traditional Chinese medicine for differential cytotoxic effects. The screening revealed 12 drugs that killed NER-deficient cells more efficiently than proficient cells. Five drugs were further analyzed for IC{sub 50} values, effects on cell cycle distribution, and induction of DNA damage. Ascaridol was the most effective compound with a difference of > 1000-fold in resistance between normal and NER-deficient cells (IC{sub 50} values for cells with deficiency in ERCC6: 0.15 μM, XPC: 0.18 μM, and normal cells: > 180 μM). NER-deficiency combined with ascaridol treatment led to G2/M-phase arrest, an increased percentage of subG1 cells, and a substantially higher DNA damage induction. These results were confirmed in a second set of NER-deficient and -proficient cell lines with isogenic background. Finally, ascaridol was characterized for its ability to generate oxidative DNA damage. The drug led to a dose-dependent increase in intracellular levels of reactive oxygen species at cytotoxic concentrations, but only NER-deficient cells showed a strongly induced amount of 8-oxodG sites. In summary, ascaridol is a cytotoxic and DNA-damaging compound which generates intracellular reactive oxidative intermediates and which selectively affects NER-deficient cells. This could provide a new therapeutic option to treat cancer cells with mutations in NER genes. -- Highlights: ► Thousand-fold higher Ascaridol activity in NER-deficient versus proficient cells. ► Impaired repair of Ascaridol-induced oxidative DNA damage in NER-deficient cells. ► Selective activity of Ascaridol opens new therapy

  7. DNA polymerase β: A missing link of the base excision repair machinery in mammalian mitochondria.

    Science.gov (United States)

    Prasad, Rajendra; Çağlayan, Melike; Dai, Da-Peng; Nadalutti, Cristina A; Zhao, Ming-Lang; Gassman, Natalie R; Janoshazi, Agnes K; Stefanick, Donna F; Horton, Julie K; Krasich, Rachel; Longley, Matthew J; Copeland, William C; Griffith, Jack D; Wilson, Samuel H

    2017-12-01

    Mitochondrial genome integrity is fundamental to mammalian cell viability. Since mitochondrial DNA is constantly under attack from oxygen radicals released during ATP production, DNA repair is vital in removing oxidatively generated lesions in mitochondrial DNA, but the presence of a strong base excision repair system has not been demonstrated. Here, we addressed the presence of such a system in mammalian mitochondria involving the primary base lesion repair enzyme DNA polymerase (pol) β. Pol β was localized to mammalian mitochondria by electron microscopic-immunogold staining, immunofluorescence co-localization and biochemical experiments. Extracts from purified mitochondria exhibited base excision repair activity that was dependent on pol β. Mitochondria from pol β-deficient mouse fibroblasts had compromised DNA repair and showed elevated levels of superoxide radicals after hydrogen peroxide treatment. Mitochondria in pol β-deficient fibroblasts displayed altered morphology by electron microscopy. These results indicate that mammalian mitochondria contain an efficient base lesion repair system mediated in part by pol β and thus pol β plays a role in preserving mitochondrial genome stability. Published by Elsevier B.V.

  8. The amino-terminal tails of histones H2A and H3 coordinate efficient base excision repair, DNA damage signaling and postreplication repair in Saccharomyces cerevisiae

    Science.gov (United States)

    Meas, Rithy; Smerdon, Michael J.; Wyrick, John J.

    2015-01-01

    Histone amino-terminal tails (N-tails) are required for cellular resistance to DNA damaging agents; therefore, we examined the role of histone N-tails in regulating DNA damage response pathways in Saccharomyces cerevisiae. Combinatorial deletions reveal that the H2A and H3 N-tails are important for the removal of MMS-induced DNA lesions due to their role in regulating the basal and MMS-induced expression of DNA glycosylase Mag1. Furthermore, overexpression of Mag1 in a mutant lacking the H2A and H3 N-tails rescues base excision repair (BER) activity but not MMS sensitivity. We further show that the H3 N-tail functions in the Rad9/Rad53 DNA damage signaling pathway, but this function does not appear to be the primary cause of MMS sensitivity of the double tailless mutants. Instead, epistasis analyses demonstrate that the tailless H2A/H3 phenotypes are in the RAD18 epistasis group, which regulates postreplication repair. We observed increased levels of ubiquitylated PCNA and significantly lower mutation frequency in the tailless H2A/H3 mutant, indicating a defect in postreplication repair. In summary, our data identify novel roles of the histone H2A and H3 N-tails in (i) regulating the expression of a critical BER enzyme (Mag1), (ii) supporting efficient DNA damage signaling and (iii) facilitating postreplication repair. PMID:25897129

  9. Structure and expression of the excision repair gene ERCC6, involved in the human disorder Cockayne's syndrome group B.

    NARCIS (Netherlands)

    C. Troelstra (Christine); W. Hesen; D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1993-01-01

    textabstractThe human repair gene ERCC6--a presumed DNA (or RNA) helicase--has recently been found to function specifically in preferential nucleotide excision repair (NER). This NER subpathway is primarily directed towards repair of (the transcribed strand of) active genes. Mutations in the ERCC6

  10. Loss of Nucleotide Excision Repair as a Source of Genomic Instability in Breast Cancer

    Science.gov (United States)

    2005-06-01

    sequence-specific mechanism of nucleotide excision repair. Genes Dev., 13, 768-785. DNA binding by short single strands of DNA requires the p53 C... Arabidopsis thaliana . The advantage signal (27). CPD-3 cells were further subcloned by single cell dilution, of using XP-A cells completely deficient...developed and optimized a novel technique for the detection of localized DNA damage and damage binding proteins in individual cells, using targeted

  11. Removal of misincorporated ribonucleotides from prokaryotic genomes: an unexpected role for nucleotide excision repair.

    Directory of Open Access Journals (Sweden)

    Alexandra Vaisman

    2013-11-01

    Full Text Available Stringent steric exclusion mechanisms limit the misincorporation of ribonucleotides by high-fidelity DNA polymerases into genomic DNA. In contrast, low-fidelity Escherichia coli DNA polymerase V (pol V has relatively poor sugar discrimination and frequently misincorporates ribonucleotides. Substitution of a steric gate tyrosine residue with alanine (umuC_Y11A reduces sugar selectivity further and allows pol V to readily misincorporate ribonucleotides as easily as deoxynucleotides, whilst leaving its poor base-substitution fidelity essentially unchanged. However, the mutability of cells expressing the steric gate pol V mutant is very low due to efficient repair mechanisms that are triggered by the misincorporated rNMPs. Comparison of the mutation frequency between strains expressing wild-type and mutant pol V therefore allows us to identify pathways specifically directed at ribonucleotide excision repair (RER. We previously demonstrated that rNMPs incorporated by umuC_Y11A are efficiently removed from DNA in a repair pathway initiated by RNase HII. Using the same approach, we show here that mismatch repair and base excision repair play minimal back-up roles in RER in vivo. In contrast, in the absence of functional RNase HII, umuC_Y11A-dependent mutagenesis increases significantly in ΔuvrA, uvrB5 and ΔuvrC strains, suggesting that rNMPs misincorporated into DNA are actively repaired by nucleotide excision repair (NER in vivo. Participation of NER in RER was confirmed by reconstituting ribonucleotide-dependent NER in vitro. We show that UvrABC nuclease-catalyzed incisions are readily made on DNA templates containing one, two, or five rNMPs and that the reactions are stimulated by the presence of mispaired bases. Similar to NER of DNA lesions, excision of rNMPs proceeds through dual incisions made at the 8(th phosphodiester bond 5' and 4(th-5(th phosphodiester bonds 3' of the ribonucleotide. Ribonucleotides misinserted into DNA can therefore be

  12. Mesh Sutured Repairs of Abdominal Wall Defects

    Science.gov (United States)

    Lanier, Steven T.; Jordan, Sumanas W.; Miller, Kyle R.; Ali, Nada A.; Stock, Stuart R.

    2016-01-01

    Background: A new closure technique is introduced, which uses strips of macroporous polypropylene mesh as a suture for closure of abdominal wall defects due to failures of standard sutures and difficulties with planar meshes. Methods: Strips of macroporous polypropylene mesh of 2 cm width were passed through the abdominal wall and tied as simple interrupted sutures. The surgical technique and surgical outcomes are presented. Results: One hundred and seven patients underwent a mesh sutured abdominal wall closure. Seventy-six patients had preoperative hernias, and the mean hernia width by CT scan for those with scans was 9.1 cm. Forty-nine surgical fields were clean-contaminated, contaminated, or dirty. Five patients had infections within the first 30 days. Only one knot was removed as an office procedure. Mean follow-up at 234 days revealed 4 recurrent hernias. Conclusions: Mesh sutured repairs reliably appose tissue under tension using concepts of force distribution and resistance to suture pull-through. The technique reduces the amount of foreign material required in comparison to sheet meshes, and avoids the shortcomings of monofilament sutures. Mesh sutured closures seem to be tolerant of bacterial contamination with low hernia recurrence rates and have replaced our routine use of mesh sheets and bioprosthetic grafts. PMID:27757361

  13. 'Batman excision' of ventral skin in hypospadias repair, clue to aesthetic repair (point of technique).

    Science.gov (United States)

    Hoebeke, P B; De Kuyper, P; Van Laecke, E

    2002-11-01

    In the hypospadiac penis the ventral skin is poorly developed, while dorsal skin is redundant. The classical Byars' flaps are a way to use the excess dorsal skin to cover the penile shaft. The appearance after Byars' flaps however is not natural. We use a more natural looking skin allocation with superior aesthetic results. The clue in this reconstruction is an inverted triangle shaped excision of ventral skin expanding over the edges of the hooded prepuce (which makes it look like Batman). After excision of the ventral skin it is possible to close the penile skin in the midline, thus mimicking the natural raphe. In case of preputial reconstruction the excised ventral skin makes the prepuce look more natural. The trend of further refining aesthetic appearance of the hypospadiac penis often neglects the penile skin reconstruction. A technique is presented by which the total penile appearances after surgery ameliorates due to better skin reconstruction.

  14. Processing closely spaced lesions during Nucleotide Excision Repair triggers mutagenesis in E. coli.

    Directory of Open Access Journals (Sweden)

    Régine Janel-Bintz

    2017-07-01

    Full Text Available It is generally assumed that most point mutations are fixed when damage containing template DNA undergoes replication, either right at the fork or behind the fork during gap filling. Here we provide genetic evidence for a pathway, dependent on Nucleotide Excision Repair, that induces mutations when processing closely spaced lesions. This pathway, referred to as Nucleotide Excision Repair-induced Mutagenesis (NERiM, exhibits several characteristics distinct from mutations that occur within the course of replication: i following UV irradiation, NER-induced mutations are fixed much more rapidly (t ½ ≈ 30 min than replication dependent mutations (t ½ ≈ 80-100 min ii NERiM specifically requires DNA Pol IV in addition to Pol V iii NERiM exhibits a two-hit dose-response curve that suggests processing of closely spaced lesions. A mathematical model let us define the geometry (infer the structure of the toxic intermediate as being formed when NER incises a lesion that resides in close proximity of another lesion in the complementary strand. This critical NER intermediate requires Pol IV / Pol II for repair, it is either lethal if left unrepaired or mutation-prone when repaired. Finally, NERiM is found to operate in stationary phase cells providing an intriguing possibility for ongoing evolution in the absence of replication.

  15. Evidence for the involvement of nucleotide excision repair in the removal of abasic sites in yeast.

    Science.gov (United States)

    Torres-Ramos, C A; Johnson, R E; Prakash, L; Prakash, S

    2000-05-01

    In eukaryotes, DNA damage induced by ultraviolet light and other agents which distort the helix is removed by nucleotide excision repair (NER) in a fragment approximately 25 to 30 nucleotides long. In humans, a deficiency in NER causes xeroderma pigmentosum (XP), characterized by extreme sensitivity to sunlight and a high incidence of skin cancers. Abasic (AP) sites are formed in DNA as a result of spontaneous base loss and from the action of DNA glycosylases involved in base excision repair. In Saccharomyces cerevisiae, AP sites are removed via the action of two class II AP endonucleases, Apn1 and Apn2. Here, we provide evidence for the involvement of NER in the removal of AP sites and show that NER competes with Apn1 and Apn2 in this repair process. Inactivation of NER in the apn1Delta or apn1Delta apn2Delta strain enhances sensitivity to the monofunctional alkylating agent methyl methanesulfonate and leads to further impairment in the cellular ability to remove AP sites. A deficiency in the repair of AP sites may contribute to the internal cancers and progressive neurodegeneration that occur in XP patients.

  16. Interactions involving the human RNA polymerase II transcription/nucleotide excision repair complex TFIIH, the nucleotide excision repair protein XPG, and Cockayne syndrome group B (CSB) protein.

    Science.gov (United States)

    Iyer, N; Reagan, M S; Wu, K J; Canagarajah, B; Friedberg, E C

    1996-02-20

    The human basal transcription factor TFIIH plays a central role in two distinct processes. TFIIH is an obligatory component of the RNA polymerase II (RNAP II) transcription initiation complex. Additionally, it is believed to be the core structure around which some if not all the components of the nucleotide excision repair (NER) machinery assemble to constitute a nucleotide excision repairosome. At least two of the subunits of TFIIH (XPB and XPD proteins) are implicated in the disease xeroderma pigmentosum (XP). We have exploited the availability of the cloned XPB, XPD, p62, p44, and p34 genes (all of which encode polypeptide subunits of TFIIH) to examine interactions between in vitro-translated polypeptides by co-immunoprecipitation. Additionally we have examined interactions between TFIIH components, the human NER protein XPG, and the CSB protein which is implicated in Cockayne syndrome (CS). Our analyses demonstrate that the XPB, XPD, p44, and p62 proteins interact with each other. XPG protein interacts with multiple subunits of TFIIH and with CSB protein.

  17. Fluorodeoxyuridine modulates cellular expression of the DNA base excision repair enzyme uracil-DNA glycosylase.

    Science.gov (United States)

    Fischer, Jennifer A; Muller-Weeks, Susan; Caradonna, Salvatore J

    2006-09-01

    The thymidylate synthase inhibitor 5-fluorouracil (5-FU) continues to play a pivotal role in the treatment of cancer. A downstream event of thymidylate synthase inhibition involves the induction of a self-defeating base excision repair process. With the depletion of TTP pools, there is also an increase in dUMP. Metabolism of dUMP to the triphosphate dUTP results in elevated pools of this atypical precursor for DNA synthesis. Under these conditions, there is a destructive cycle of dUMP incorporation into DNA, removal of uracil by the base excision repair enzyme uracil-DNA glycosylase (UDG), and reincorporation of dUMP during the synthesis phase of DNA repair. The end point is DNA strand breaks and loss of DNA integrity, which contributes to cell death. Evidence presented here indicates that both the nuclear and the mitochondrial isoforms of UDG are modulated by FdUrd (and 5-FU) treatment in certain cell lines but not in others. Modulation occurs at the transcriptional and post-translational levels. Under normal conditions, nUDG protein appears in G(1) and is degraded during the S to G(2) phase transition. The present study provides evidence that, in certain cell lines, FdUrd mediates an atypical turnover of nUDG. Additional data indicate that, for cell lines that do not down-regulate nUDG, small interfering RNA-mediated knockdown of nUDG significantly increases resistance to the cytotoxic effects of FdUrd. Results from these studies show that nUDG is an additional determinant in FdUrd-mediated cytotoxicity and bolster the notion that the self-defeating base excision repair pathway, instigated by elevated dUTP (FdUTP) pools, contributes to the cytotoxic consequences of 5-FU chemotherapy.

  18. Differential role of base excision repair proteins in mediating cisplatin cytotoxicity.

    Science.gov (United States)

    Sawant, Akshada; Floyd, Ashley M; Dangeti, Mohan; Lei, Wen; Sobol, Robert W; Patrick, Steve M

    2017-03-01

    Interstrand crosslinks (ICLs) are covalent lesions formed by cisplatin. The mechanism for the processing and removal of ICLs by DNA repair proteins involves nucleotide excision repair (NER), homologous recombination (HR) and fanconi anemia (FA) pathways. In this report, we monitored the processing of a flanking uracil adjacent to a cisplatin ICL by the proteins involved in the base excision repair (BER) pathway. Using a combination of extracts, purified proteins, inhibitors, functional assays and cell culture studies, we determined the specific BER proteins required for processing a DNA substrate with a uracil adjacent to a cisplatin ICL. Uracil DNA glycosylase (UNG) is the primary glycosylase responsible for the removal of uracils adjacent to cisplatin ICLs, whereas other uracil glycosylases can process uracils in the context of undamaged DNA. Repair of the uracil adjacent to cisplatin ICLs proceeds through the classical BER pathway, highlighting the importance of specific proteins in this redundant pathway. Removal of uracil is followed by the generation of an abasic site and subsequent cleavage by AP endonuclease 1 (APE1). Inhibition of either the repair or redox domain of APE1 gives rise to cisplatin resistance. Inhibition of the lyase domain of Polymerase β (Polβ) does not influence cisplatin cytotoxicity. In addition, lack of XRCC1 leads to increased DNA damage and results in increased cisplatin cytotoxicity. Our results indicate that BER activation at cisplatin ICLs influences crosslink repair and modulates cisplatin cytotoxicity via specific UNG, APE1 and Polβ polymerase functions. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. DREMECELS: A Curated Database for Base Excision and Mismatch Repair Mechanisms Associated Human Malignancies.

    Directory of Open Access Journals (Sweden)

    Ankita Shukla

    Full Text Available DNA repair mechanisms act as a warrior combating various damaging processes that ensue critical malignancies. DREMECELS was designed considering the malignancies with frequent alterations in DNA repair pathways, that is, colorectal and endometrial cancers, associated with Lynch syndrome (also known as HNPCC. Since lynch syndrome carries high risk (~40-60% for both cancers, therefore we decided to cover all three diseases in this portal. Although a large population is presently affected by these malignancies, many resources are available for various cancer types but no database archives information on the genes specifically for only these cancers and disorders. The database contains 156 genes and two repair mechanisms, base excision repair (BER and mismatch repair (MMR. Other parameters include some of the regulatory processes that have roles in these disease progressions due to incompetent repair mechanisms, specifically BER and MMR. However, our unique database mainly provides qualitative and quantitative information on these cancer types along with methylation, drug sensitivity, miRNAs, copy number variation (CNV and somatic mutations data. This database would serve the scientific community by providing integrated information on these disease types, thus sustaining diagnostic and therapeutic processes. This repository would serve as an excellent accompaniment for researchers and biomedical professionals and facilitate in understanding such critical diseases. DREMECELS is publicly available at http://www.bioinfoindia.org/dremecels.

  20. 49 CFR 192.245 - Repair or removal of defects.

    Science.gov (United States)

    2010-10-01

    ... NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Welding of Steel in Pipelines § 192... weld must be removed if it has a crack that is more than 8 percent of the weld length. (b) Each weld...) Repair of a crack, or of any defect in a previously repaired area must be in accordance with written weld...

  1. Repair of Defective Composite Resin Restoration: Current Trend ...

    African Journals Online (AJOL)

    Background: Repair of defective composite resins restorations is being increasingly recognized as a viable alternative to replacement. there is however no consensus yet on the treatment protocol. Objective: To determine the views and practice of specialists in Conservative Dentistry in Nigeria as regard to repair procedure ...

  2. Nucleotide Excision Repair in Cellular Chromatin: Studies with Yeast from Nucleotide to Gene to Genome

    Directory of Open Access Journals (Sweden)

    Simon Reed

    2012-09-01

    Full Text Available Here we review our development of, and results with, high resolution studies on global genome nucleotide excision repair (GGNER in Saccharomyces cerevisiae. We have focused on how GGNER relates to histone acetylation for its functioning and we have identified the histone acetyl tranferase Gcn5 and acetylation at lysines 9/14 of histone H3 as a major factor in enabling efficient repair. We consider results employing primarily MFA2 as a model gene, but also those with URA3 located at subtelomeric sequences. In the latter case we also see a role for acetylation at histone H4. We then go on to outline the development of a high resolution genome-wide approach that enables one to examine correlations between histone modifications and the nucleotide excision repair (NER of UV-induced cyclobutane pyrimidine dimers throughout entire genomes. This is an approach that will enable rapid advances in understanding the complexities of how compacted chromatin in chromosomes is processed to access DNA damage and then returned to its pre-damaged status to maintain epigenetic codes.

  3. Irofulven cytotoxicity depends on transcription-coupled nucleotide excision repair and is correlated with XPG expression in solid tumor cells.

    Science.gov (United States)

    Koeppel, Florence; Poindessous, Virginie; Lazar, Vladimir; Raymond, Eric; Sarasin, Alain; Larsen, Annette K

    2004-08-15

    Irofulven is a novel alkylating agent with promising clinical activity, particularly toward ovarian and hormone-refractory prostate cancers. To facilitate additional clinical development, we have aimed to identify biological markers associated with sensitivity to the compound. Fibroblasts derived from patients with xeroderma pigmentosum or Cockayne's syndrome along with a panel of 20 human cancer cell lines (eight different tumor types) were examined to establish the importance of nucleotide excision repair proteins in the sensitivity to irofulven. Human cells deficient in nucleotide excision repair are up to 30-fold more sensitive to the cytotoxic effects of irofulven compared with repair-proficient controls, clearly indicating that nucleotide excision repair plays a crucial role in the sensitivity to the drug. Interestingly, our results show that irofulven-induced lesions are recognized by transcription-coupled repair but not by global genome repair. Another unique feature is the pronounced sensitivity of XPD and XPB helicase-deficient cells to the drug. Comparison of the IC50 values for irofulven, cisplatin, and ecteinascidin 743 with the expression levels of ERCC1, XPD, and XPG genes in different solid tumor cell lines shows no correlation between the expression levels of any of the three nucleotide excision repair proteins and the sensitivity to ecteinascidin 743. In contrast, expression of the XPG endonuclease was correlated with the cytotoxicity for irofulven and, to a lesser degree, for cisplatin. Importantly, XPG expression was also correlated with cellular nucleotide excision repair activity. Increasing evidence indicates that compromised nucleotide excision repair activity is frequent in several solid tumor types. The results presented here suggest that XPG expression in such tumors may be a useful marker to predict their sensitivity to irofulven.

  4. Extracts of proliferating and non-proliferating human cells display different base excision pathways and repair fidelity

    DEFF Research Database (Denmark)

    Akbari, Mansour; Pena Diaz, Javier; Andersen, Sonja

    2009-01-01

    Base excision repair (BER) of damaged or inappropriate bases in DNA has been reported to take place by single nucleotide insertion or through incorporation of several nucleotides, termed short-patch and long-patch repair, respectively. We found that extracts from proliferating and non-proliferati...

  5. New design of nucleotide excision repair (NER) inhibitors for combination cancer therapy.

    Science.gov (United States)

    Gentile, Francesco; Tuszynski, Jack A; Barakat, Khaled H

    2016-04-01

    Many cancer chemotherapy agents act by targeting the DNA of cancer cells, causing substantial damage within their genome and causing them to undergo apoptosis. An effective DNA repair pathway in cancer cells can act in a reverse way by removing these drug-induced DNA lesions, allowing cancer cells to survive, grow and proliferate. In this context, DNA repair inhibitors opened a new avenue in cancer treatment, by blocking the DNA repair mechanisms from removing the chemotherapy-mediated DNA damage. In particular, the nucleotide excision repair (NER) involves more than thirty protein-protein interactions and removes DNA adducts caused by platinum-based chemotherapy. The excision repair cross-complementation group 1 (ERCC1)-xeroderma pigmentosum, complementation group A (XPA) protein (XPA-ERCC1) complex seems to be one of the most promising targets in this pathway. ERCC1 is over expressed in cancer cells and the only known cellular function so far for XPA is to recruit ERCC1 to the damaged point. Here, we build upon our recent advances in identifying inhibitors for this interaction and continue our efforts to rationally design more effective and potent regulators for the NER pathway. We employed in silico drug design techniques to: (1) identify compounds similar to the recently discovered inhibitors, but more effective at inhibiting the XPA-ERCC1 interactions, and (2) identify different scaffolds to develop novel lead compounds. Two known inhibitor structures have been used as starting points for two ligand/structure-hybrid virtual screening approaches. The findings described here form a milestone in discovering novel inhibitors for the NER pathway aiming at improving the efficacy of current platinum-based therapy, by modulating the XPA-ERCC1 interaction. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Acetylation regulates WRN catalytic activities and affects base excision DNA repair

    DEFF Research Database (Denmark)

    Muftuoglu, Meltem; Kusumoto, Rika; Speina, Elzbieta

    2008-01-01

    The Werner protein (WRN), defective in the premature aging disorder Werner syndrome, participates in a number of DNA metabolic processes, and we have been interested in the possible regulation of its function in DNA repair by post-translational modifications. Acetylation mediated by histone...

  7. A Novel Esthetic Approach using Connective Tissue Graft for Soft Tissue Defect Following Surgical Excision of Gingival Fibrolipoma

    OpenAIRE

    Balasundaram, Aruna; Parthasarathy, Harinath; Kumar, Praveenkrishna; Gajendran, Priyalochana; Appukuttan, Devapriya

    2014-01-01

    The aim of the present case report is to evaluate the adjunctive use of a connective tissue graft to overcome soft tissue defects following excision of a gingival fibrolipoma in the aesthetic region. Connective tissue graft has been well documented for treating defects of esthetic concern. However, the literature does not contain many reports on the esthetic clinical outcome following the use of connective tissue graft secondary to excision of soft tissue tumours. A 28-year-old male patient r...

  8. 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

  9. Clinicopathologic factors identify sporadic mismatch repair-defective colon cancers

    DEFF Research Database (Denmark)

    Halvarsson, Britta; Anderson, Harald; Domanska, Katarina

    2008-01-01

    Identification of sporadic mismatch repair (MMR)-defective colon cancers is increasingly demanded for decisions on adjuvant therapies. We evaluated clinicopathologic factors for the identification of these prognostically favorable tumors. Histopathologic features in 238 consecutive colon cancers...... and excluded 61.5% of the tumors from MMR testing. This clinicopathologic index thus successfully selects MMR-defective colon cancers. Udgivelsesdato: 2008-Feb...

  10. Abnormal Base Excision Repair at Trinucleotide Repeats Associated with Diseases: A Tissue-Selective Mechanism

    Directory of Open Access Journals (Sweden)

    Agathi-Vasiliki Goula

    2013-07-01

    Full Text Available More than fifteen genetic diseases, including Huntington’s disease, myotonic dystrophy 1, fragile X syndrome and Friedreich ataxia, are caused by the aberrant expansion of a trinucleotide repeat. The mutation is unstable and further expands in specific cells or tissues with time, which can accelerate disease progression. DNA damage and base excision repair (BER are involved in repeat instability and might contribute to the tissue selectivity of the process. In this review, we will discuss the mechanisms of trinucleotide repeat instability, focusing more specifically on the role of BER.

  11. A novel role for transcription-coupled nucleotide excision repair for the in vivo repair of 3,N4-ethenocytosine.

    Science.gov (United States)

    Chaim, Isaac A; Gardner, Alycia; Wu, Jie; Iyama, Teruaki; Wilson, David M; Samson, Leona D

    2017-04-07

    Etheno (ε) DNA base adducts are highly mutagenic lesions produced endogenously via reactions with lipid peroxidation (LPO) products. Cancer-promoting conditions, such as inflammation, can induce persistent oxidative stress and increased LPO, resulting in the accumulation of ε-adducts in different tissues. Using a recently described fluorescence multiplexed host cell reactivation assay, we show that a plasmid reporter bearing a site-specific 3,N4-ethenocytosine (εC) causes transcriptional blockage. Notably, this blockage is exacerbated in Cockayne Syndrome and xeroderma pigmentosum patient-derived lymphoblastoid and fibroblast cells. Parallel RNA-Seq expression analysis of the plasmid reporter identifies novel transcriptional mutagenesis properties of εC. Our studies reveal that beyond the known pathways, such as base excision repair, the process of transcription-coupled nucleotide excision repair plays a role in the removal of εC from the genome, and thus in the protection of cells and tissues from collateral damage induced by inflammatory responses. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  12. Studies on reconstruction of large skin defects following mammary tumor excision in dogs

    Directory of Open Access Journals (Sweden)

    Sabarish Babu Malli Sadhasivan

    2017-12-01

    Full Text Available Aim: The main objective of the study was to describe the use of skin fold advancement flaps (SFAFs and other reconstructive techniques for closure of large skin defects following mammary tumor excision in dogs. Materials and Methods: Twelve dogs underwent reconstruction of large ventral skin defects following mammary tumor excision with wide margins. Skin fold flaps (flank fold flap and elbow fold flap were elevated from the flank and elbow region, respectively, and transposed and sutured onto the large ventral skin defect following mastectomy in all the dogs. In addition to the skin fold flaps, other reconstructive techniques such as undermining, walking sutures, and tension-relieving suture techniques were followed during surgery in the closure of large skin defects without skin tension and compromising limb mobility. The skin flap viability was assessed subjectively by gross observation of the flap such as color, temperature, capillary perfusion, and cosmetic appearance, and scoring (1-4 was done. Tissue samples were collected from a surgical site on days 3, 6, and 12 post-operatively for histopathological evaluation and healing status of the skin flap. Results: All the surgical wounds healed primarily, without any major complications and the skin flap remained healthy throughout the healing process post-operatively. Distal flap necrosis was noticed in one case and necrosis of skin flap between two suture lines was noticed in another case in which the necrotized distal portion healed by secondary intention after 7 days. The mean survival of subdermal plexus flap in the above cases was 98% which was a subjective evaluation based on surface area of the skin defect measured by Image 'J software and the flap dimensions. The average healing of skin flap in days was 14.91±0.86. Conclusion: The SFAFs along with other reconstructive techniques help in the reconstruction of large ventral skin defects following mastectomy in dogs without much

  13. The amino-terminal tails of histones H2A and H3 coordinate efficient base excision repair, DNA damage signaling and postreplication repair in Saccharomyces cerevisiae.

    Science.gov (United States)

    Meas, Rithy; Smerdon, Michael J; Wyrick, John J

    2015-05-26

    Histone amino-terminal tails (N-tails) are required for cellular resistance to DNA damaging agents; therefore, we examined the role of histone N-tails in regulating DNA damage response pathways in Saccharomyces cerevisiae. Combinatorial deletions reveal that the H2A and H3 N-tails are important for the removal of MMS-induced DNA lesions due to their role in regulating the basal and MMS-induced expression of DNA glycosylase Mag1. Furthermore, overexpression of Mag1 in a mutant lacking the H2A and H3 N-tails rescues base excision repair (BER) activity but not MMS sensitivity. We further show that the H3 N-tail functions in the Rad9/Rad53 DNA damage signaling pathway, but this function does not appear to be the primary cause of MMS sensitivity of the double tailless mutants. Instead, epistasis analyses demonstrate that the tailless H2A/H3 phenotypes are in the RAD18 epistasis group, which regulates postreplication repair. We observed increased levels of ubiquitylated PCNA and significantly lower mutation frequency in the tailless H2A/H3 mutant, indicating a defect in postreplication repair. In summary, our data identify novel roles of the histone H2A and H3 N-tails in (i) regulating the expression of a critical BER enzyme (Mag1), (ii) supporting efficient DNA damage signaling and (iii) facilitating postreplication repair. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  14. Biochemical characterization and DNA repair pathway interactions of Mag1-mediated base excision repair in Schizosaccharomyces pombe.

    Science.gov (United States)

    Alseth, Ingrun; Osman, Fikret; Korvald, Hanne; Tsaneva, Irina; Whitby, Matthew C; Seeberg, Erling; Bjørås, Magnar

    2005-01-01

    The Schizosaccharomyces pombe mag1 gene encodes a DNA repair enzyme with sequence similarity to the AlkA family of DNA glycosylases, which are essential for the removal of cytotoxic alkylation products, the premutagenic deamination product hypoxanthine and certain cyclic ethenoadducts such as ethenoadenine. In this paper, we have purified the Mag1 protein and characterized its substrate specificity. It appears that the substrate range of Mag1 is limited to the major alkylation products, such as 3-mA, 3-mG and 7-mG, whereas no significant activity was found towards deamination products, ethenoadducts or oxidation products. The efficiency of 3-mA and 3-mG removal was 5-10 times slower for Mag1 than for Escherichia coli AlkA whereas the rate of 7-mG removal was similar to the two enzymes. The relatively low efficiency for the removal of cytotoxic 3-methylpurines is consistent with the moderate sensitivity of the mag1 mutant to methylating agents. Furthermore, we studied the initial steps of Mag1-dependent base excision repair (BER) and genetic interactions with other repair pathways by mutant analysis. The double mutants mag1 nth1, mag1 apn2 and mag1 rad2 displayed increased resistance to methyl methanesulfonate (MMS) compared with the single mutants nth1, apn2 and rad2, respectively, indicating that Mag1 initiates both short-patch (Nth1-dependent) and long-patch (Rad2-dependent) BER of MMS-induced damage. Spontaneous intrachromosomal recombination frequencies increased 3-fold in the mag1 mutant suggesting that Mag1 and recombinational repair (RR) are both involved in repair of alkylated bases. Finally, we show that the deletion of mag1 in the background of rad16, nth1 and rad2 single mutants reduced the total recombination frequencies of all three double mutants, indicating that abasic sites formed as a result of Mag1 removal of spontaneous base lesions are substrates for nucleotide excision repair, long- and short-patch BER and RR.

  15. Oxidative and energy metabolism as potential clues for clinical heterogeneity in nucleotide excision repair disorders.

    Science.gov (United States)

    Hosseini, Mohsen; Ezzedine, Khaled; Taieb, Alain; Rezvani, Hamid R

    2015-02-01

    Nucleotide excision repair (NER) is an important DNA repair pathway involved in the removal of a wide array of DNA lesions. The absence or dysfunction of NER results in the following distinct disorders: xeroderma pigmentosum (XP), Cockayne syndrome (CS), cerebro-oculo-facio-skeletal (COFS) syndrome, UV-sensitive syndrome (UVSS), trichothiodystrophy (TTD), or combined syndromes including XP/CS, XP/TTD, CS/TTD, and COFS/TTD. In addition to their well-characterized role in the NER signaling pathway, NER factors also seem to be important in biological processes that are not directly associated with DNA damage responses, including mitochondrial function and redox homeostasis. The potential causative role of these factors in the large clinical spectrum seen in NER diseases is discussed in this review.

  16. E2F1 and p53 Transcription Factors as Accessory Factors for Nucleotide Excision Repair

    Directory of Open Access Journals (Sweden)

    David G. Johnson

    2012-10-01

    Full Text Available Many of the biochemical details of nucleotide excision repair (NER have been established using purified proteins and DNA substrates. In cells however, DNA is tightly packaged around histones and other chromatin-associated proteins, which can be an obstacle to efficient repair. Several cooperating mechanisms enhance the efficiency of NER by altering chromatin structure. Interestingly, many of the players involved in modifying chromatin at sites of DNA damage were originally identified as regulators of transcription. These include ATP-dependent chromatin remodelers, histone modifying enzymes and several transcription factors. The p53 and E2F1 transcription factors are well known for their abilities to regulate gene expression in response to DNA damage. This review will highlight the underappreciated, transcription-independent functions of p53 and E2F1 in modifying chromatin structure in response to DNA damage to promote global NER.

  17. Transcriptional and post-transcriptional regulation of nucleotide excision repair genes in human cells

    Energy Technology Data Exchange (ETDEWEB)

    Lefkofsky, Hailey B. [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Veloso, Artur [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Bioinformatics Program, Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI (United States); Ljungman, Mats, E-mail: ljungman@umich.edu [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Nucleotide excision repair (NER) removes DNA helix-distorting lesions induced by UV light and various chemotherapeutic agents such as cisplatin. These lesions efficiently block the elongation of transcription and need to be rapidly removed by transcription-coupled NER (TC-NER) to avoid the induction of apoptosis. Twenty-nine genes have been classified to code for proteins participating in nucleotide excision repair (NER) in human cells. Here we explored the transcriptional and post-transcriptional regulation of these NER genes across 13 human cell lines using Bru-seq and BruChase-seq, respectively. Many NER genes are relatively large in size and therefore will be easily inactivated by UV-induced transcription-blocking lesions. Furthermore, many of these genes produce transcripts that are rather unstable. Thus, these genes are expected to rapidly lose expression leading to a diminished function of NER. One such gene is ERCC6 that codes for the CSB protein critical for TC-NER. Due to its large gene size and high RNA turnover rate, the ERCC6 gene may act as dosimeter of DNA damage so that at high levels of damage, ERCC6 RNA levels would be diminished leading to the loss of CSB expression, inhibition of TC-NER and the promotion of cell death.

  18. Molecular cloning of the human nucleotide-excision-repair gene ERCC4

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, L.H.; Brookman, K.W.; Weber, C.A.; Salazar, E.P. [Lawrence Livermore National Lab., CA (United States); Reardon, J.T.; Sancar, A. [Univ. of North Carolina, Chapel Hill, NC (United States); Deng, Z.; Siciliano, M.J. [Univ. of Texas Cancer Center, Houston, TX (United States)

    1994-07-19

    ERCC4 was previously identified in somatic cell hybrids as a human gene that corrects the nucleotide-excision-repair deficiency in mutant hamster cells. The cloning strategy for ERCC4 involved transfection of the repair-deficient hamster cell line UV41 with a human sCos-1 cosmid library derived from chromosome 16. Enhanced UV resistance was seen with one cosmid-library transformant and two secondary transformants of UV41. Cosmid clones carrying a functional ERCC4 gene were isolated from a library of a second transformant by selecting in Escherichia coli for expression of a linked neomycin-resistance gene that was present in the sCos-1 vector. The cosmids mapped to 16p13.13-p13.2, the location assigned to ERCC4 by using somatic cell hybrids. Upon transfection into UV41, six cosmid clones gave partial correction ranging from 30% to 64%, although all appeared to contain the complete gene. The capacity for in vitro excision of thymine dimers from a plasmid by transformant cell extracts correlated qualitatively with enhanced UV resistance.

  19. Polymorphisms within base and nucleotide excision repair pathways and risk of differentiated thyroid carcinoma.

    Science.gov (United States)

    Cipollini, Monica; Figlioli, Gisella; Maccari, Giuseppe; Garritano, Sonia; De Santi, Chiara; Melaiu, Ombretta; Barone, Elisa; Bambi, Franco; Ermini, Stefano; Pellegrini, Giovanni; Cristaudo, Alfonso; Foddis, Rudy; Bonotti, Alessandra; Romei, Cristina; Vivaldi, Agnese; Agate, Laura; Molinari, Eleonora; Barale, Roberto; Forsti, Asta; Hemminki, Kari; Elisei, Rossella; Gemignani, Federica; Landi, Stefano

    2016-05-01

    The thyrocytes are exposed to high levels of oxidative stress which could induce DNA damages. Base excision repair (BER) is one of the principal mechanisms of defense against oxidative DNA damage, however recent evidences suggest that also nucleotide excision repair (NER) could be involved. The aim of present work was to identify novel differentiated thyroid cancer (DTC) risk variants in BER and NER genes. For this purpose, the most strongly associated SNPs within NER and BER genes found in our previous GWAS on DTC were selected and replicated in an independent series of samples for a new case-control study. Although a positive signal was detected at the nominal level of 0.05 for rs7689099 (encoding for an aminoacid change proline to arginine at codon 117 within NEIL3), none of the considered SNPs (i.e. rs7990340 and rs690860 within RFC3, rs3744767 and rs1131636 within RPA1, rs16962916 and rs3136166 in ERCC4, and rs17739370 and rs7689099 in NEIL3) was associated with the risk of DTC when the correction of multiple testing was applied. In conclusion, a role of NER and BER pathways was evoked in the susceptibility to DTC. However, this seemed to be limited to few polymorphic genes and the overall effect size appeared weak. Copyright © 2016. Published by Elsevier B.V.

  20. Membrane association of mitochondrial DNA facilitates base excision repair in mammalian mitochondria.

    Science.gov (United States)

    Boesch, Pierre; Ibrahim, Noha; Dietrich, André; Lightowlers, Robert N

    2010-03-01

    Mitochondrial DNA encodes a set of 13 polypeptides and is subjected to constant oxidative stress due to ROS production within the organelle. It has been shown that DNA repair in the mitochondrion proceeds through both short- and long-patch base excision repair (BER). In the present article, we have used the natural competence of mammalian mitochondria to import DNA and study the sub-mitochondrial localization of the repair system in organello. Results demonstrate that sequences corresponding to the mtDNA non-coding region interact with the inner membrane in a rapid and saturable fashion. We show that uracil containing import substrates are taken into the mitochondrion and are used as templates for damage driven DNA synthesis. After further sub-fractionation, we show that the length of the repair synthesis patch differs in the soluble and the particulate fraction. Bona fide long patch BER synthesis occurs on the DNA associated with the particulate fraction, whereas a nick driven DNA synthesis occurs when the uracil containing DNA accesses the soluble fraction. Our results suggest that coordinate interactions of the different partners needed for BER is only found at sites where the DNA is associated with the membrane.

  1. Base excision repair of oxidative DNA damage: from mechanism to disease

    Science.gov (United States)

    Whitaker, Amy M.; Schaich, Matthew A.; Smith, Mallory S.; Flynn, Tony S.; Freudenthal, Bret. D.

    2017-01-01

    Reactive oxygen species continuously assault the structure of DNA resulting in oxidation and fragmentation of the nucleobases. Both oxidative DNA damage itself and its repair mediate the progression of many prevalent human maladies. The major pathway tasked with removal of oxidative DNA damage, and hence maintaining genomic integrity, is base excision repair (BER). The aphorism that structure often dictates function has proven true, as numerous recent structural biology studies have aided in clarifying the molecular mechanisms used by key BER enzymes during the repair of damaged DNA. This review focuses on the mechanistic details of the individual BER enzymes and the association of these enzymes during the development and progression of human diseases, including cancer and neurological diseases. Expanding on these structural and biochemical studies to further clarify still elusive BER mechanisms, and focusing our efforts toward gaining an improved appreciation of how these enzymes form co-complexes to facilitate DNA repair is a crucial next step toward understanding how BER contributes to human maladies and how it can be manipulated to alter patient outcomes. PMID:28199214

  2. Transcription factor TFIIH and DNA endonuclease Rad2 constitute yeast nucleotide excision repair factor 3: implications for nucleotide excision repair and Cockayne syndrome.

    Science.gov (United States)

    Habraken, Y; Sung, P; Prakash, S; Prakash, L

    1996-10-01

    Nucleotide excision repair (NER) of ultraviolet light-damaged DNA in eukaryotes requires a large number of highly conserved protein factors. Recent studies in yeast have suggested that NER involves the action of distinct protein subassemblies at the damage site rather than the placement there of a "preformed repairosome" containing all the essential NER factors. Neither of the two endonucleases, Rad1-Rad10 and Rad2, required for dual incision, shows any affinity for ultraviolet-damaged DNA. Rad1-Rad10 forms a ternary complex with the DNA damage recognition protein Rad14, providing a means for targeting this nuclease to the damage site. It has remained unclear how the Rad2 nuclease is targeted to the DNA damage site and why mutations in the human RAD2 counterpart, XPG, result in Cockayne syndrome. Here we examine whether Rad2 is part of a higher order subassembly. Interestingly, we find copurification of Rad2 protein with TFIIH, such that TFIIH purified from a strain that overexpresses Rad2 contains a stoichiometric amount of Rad2. By several independent criteria, we establish that Rad2 is tightly associated with TFIIH, exhibiting an apparent dissociation constant Cockayne syndrome.

  3. Role of endonucleases XPF and XPG in nucleotide excision repair of platinated DNA and cisplatin/oxaliplatin cytotoxicity

    OpenAIRE

    Graf, Nora; Ang, Wee Han; Zhu, Guangyu; Myint, MyatNoeZin; Lippard, Stephen J.

    2011-01-01

    Resistance of tumor cells to platinum anticancer agents poses a major problem in cancer chemotherapy. One of the mechanisms associated with platinum-based drug resistance is the enhanced capacity of the cell to carry out nucleotide excision repair (NER) on platinum-damaged DNA. Endonucleases XPF and XPG are critical components of NER, responsible for excising the damaged DNA strand to remove the DNA lesion. Here, we investigated possible consequences of down-regulation of XPF and XPG gene exp...

  4. Defective transcription-coupled repair of oxidative base damage in Cockayne syndrome patients from XP group G.

    Science.gov (United States)

    Cooper, P K; Nouspikel, T; Clarkson, S G; Leadon, S A

    1997-02-14

    In normal human cells, damage due to ultraviolet light is preferentially removed from active genes by nucleotide excision repair (NER) in a transcription-coupled repair (TCR) process that requires the gene products defective in Cockayne syndrome (CS). Oxidative damage, including thymine glycols, is shown to be removed by TCR in cells from normal individuals and from xeroderma pigmentosum (XP)-A, XP-F, and XP-G patients who have NER defects but not from XP-G patients who have severe CS. Thus, TCR of oxidative damage requires an XPG function distinct from its NER endonuclease activity. These results raise the possibility that defective TCR of oxidative damage contributes to the developmental defects associated with CS.

  5. Mesh Sutured Repairs of Abdominal Wall Defects

    National Research Council Canada - National Science Library

    Lanier, Steven T; Dumanian, Gregory A; Jordan, Sumanas W; Miller, Kyle R; Ali, Nada A; Stock, Stuart R

    2016-01-01

    BACKGROUND:A new closure technique is introduced, which uses strips of macroporous polypropylene mesh as a suture for closure of abdominal wall defects due to failures of standard sutures and difficulties with planar meshes...

  6. Nucleotide excision repair is not induced in human embryonic lung fibroblasts treated with environmental pollutants.

    Directory of Open Access Journals (Sweden)

    Pavel Rossner

    Full Text Available The cellular response to genotoxic treatment depends on the cell line used. Although tumor cell lines are widely used for genotoxicity tests, the interpretation of the results may be potentially hampered by changes in cellular processes caused by malignant transformation. In our study we used normal human embryonic lung fibroblasts (HEL12469 cells and tested their response to treatment with benzo[a]pyrene (B[a]P and extractable organic matter (EOM from ambient air particles <2.5 µm (PM2.5 collected in two Czech cities differing in levels and sources of air pollution. We analyzed multiple endpoints associated with exposure to polycyclic aromatic hydrocarbons (PAHs including the levels of bulky DNA adducts and the nucleotide excision repair (NER response [expression of XPE, XPC and XPA genes on the level of mRNA and proteins, unscheduled DNA synthesis (UDS]. EOMs were collected in the winter and summer of 2011 in two Czech cities with different levels and sources of air pollution. The effects of the studied compounds were analyzed in the presence (+S9 and absence (-S9 of the rat liver microsomal S9 fraction. The levels of bulky DNA adducts were highest after treatment with B[a]P, followed by winter EOMs; their induction by summer EOMs was weak. The induction of both mRNA and protein expression was observed, with the most pronounced effects after treatment with B[a]P (-S9; the response induced by EOMs from both cities and seasons was substantially weaker. The expression of DNA repair genes was not accompanied by the induction of UDS activity. In summary, our results indicate that the tested compounds induced low levels of DNA damage and affected the expression of NER genes; however, nucleotide excision repair was not induced.

  7. MISMATCH REPAIR-DEPENDENT ITERATIVE EXCISION AT IRREPARABLE O6-METHYLGUANINE LESIONS IN HUMAN NUCLEAR EXTRACTS*

    Science.gov (United States)

    York, Sally J.; Modrich, Paul

    2008-01-01

    The response of mammalian cells to SN1 DNA methylators depends on functional MutSα and MutLα. Cells deficient in either of these activities are resistant to the cytotoxic effects of this class of chemotherapeutic drug. Because killing by SN1 methylators has been attributed to O6-methylguanine (MeG), we have constructed nicked circular heteroduplexes that contain a single MeG-T mispair and have examined processing of these molecules by mismatch repair in nuclear extracts of human cells. Excision provoked by MeG-T is restricted to the incised heteroduplex strand, leading to removal of the MeG when it resides on this strand. However, when the MeG is located on the continuous strand, the heteroduplex is irreparable. MeG-T-dependent repair DNA synthesis is observed on both reparable and irreparable, 3’ and 5’ heteroduplexes as judged by [32P]dAMP incorporation. Labeling with [α-32P]dATP followed by a cold dATP chase has demonstrated that newly synthesized DNA on irreparable molecules is subject to re-excision in a reaction that is MutLα-dependent, an effect attributable to presence of MeG on the template strand. Processing of the irreparable 3’ heteroduplex is also associated with incision of the discontinuous strand of a few percent of molecules near the thymidylate of the MeG-T base pair. These results provide the first direct evidence for mismatch repair-mediated iterative processing of DNA methylator damage, an effect that may be relevant to damage signaling events triggered by this class of chemotherapeutic agent. PMID:16772289

  8. Base excision DNA repair in the embryonic development of the sea urchin, Strongylocentrotus intermedius.

    Science.gov (United States)

    Torgasheva, Natalya A; Menzorova, Natalya I; Sibirtsev, Yurii T; Rasskazov, Valery A; Zharkov, Dmitry O; Nevinsky, Georgy A

    2016-06-21

    In actively proliferating cells, such as the cells of the developing embryo, DNA repair is crucial for preventing the accumulation of mutations and synchronizing cell division. Sea urchin embryo growth was analyzed and extracts were prepared. The relative activity of DNA polymerase, apurinic/apyrimidinic (AP) endonuclease, uracil-DNA glycosylase, 8-oxoguanine-DNA glycosylase, and other glycosylases was analyzed using specific oligonucleotide substrates of these enzymes; the reaction products were resolved by denaturing 20% polyacrylamide gel electrophoresis. We have characterized the profile of several key base excision repair activities in the developing embryos (2 blastomers to mid-pluteus) of the grey sea urchin, Strongylocentrotus intermedius. The uracil-DNA glycosylase specific activity sharply increased after blastula hatching, whereas the specific activity of 8-oxoguanine-DNA glycosylase steadily decreased over the course of the development. The AP-endonuclease activity gradually increased but dropped at the last sampled stage (mid-pluteus 2). The DNA polymerase activity was high at the first cleavage division and then quickly decreased, showing a transient peak at blastula hatching. It seems that the developing sea urchin embryo encounters different DNA-damaging factors early in development within the protective envelope and later as a free-floating larva, with hatching necessitating adaptation to the shift in genotoxic stress conditions. No correlation was observed between the dynamics of the enzyme activities and published gene expression data from developing congeneric species, S. purpuratus. The results suggest that base excision repair enzymes may be regulated in the sea urchin embryos at the level of covalent modification or protein stability.

  9. Selective base excision repair of DNA damage by the non-base-flipping DNA glycosylase AlkC

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Rongxin; Mullins, Elwood A.; Shen, Xing; #8208; Xing; Lay, Kori T.; Yuen, Philip K.; David, Sheila S.; Rokas, Antonis; Eichman, Brandt F. (UCD); (Vanderbilt)

    2017-10-20

    DNA glycosylases preserve genome integrity and define the specificity of the base excision repair pathway for discreet, detrimental modifications, and thus, the mechanisms by which glycosylases locate DNA damage are of particular interest. Bacterial AlkC and AlkD are specific for cationic alkylated nucleobases and have a distinctive HEAT-like repeat (HLR) fold. AlkD uses a unique non-base-flipping mechanism that enables excision of bulky lesions more commonly associated with nucleotide excision repair. In contrast, AlkC has a much narrower specificity for small lesions, principally N3-methyladenine (3mA). Here, we describe how AlkC selects for and excises 3mA using a non-base-flipping strategy distinct from that of AlkD. A crystal structure resembling a catalytic intermediate complex shows how AlkC uses unique HLR and immunoglobulin-like domains to induce a sharp kink in the DNA, exposing the damaged nucleobase to active site residues that project into the DNA. This active site can accommodate and excise N3-methylcytosine (3mC) and N1-methyladenine (1mA), which are also repaired by AlkB-catalyzed oxidative demethylation, providing a potential alternative mechanism for repair of these lesions in bacteria.

  10. Repair of a common bile duct defect with a decellularized ureteral graft.

    Science.gov (United States)

    Cheng, Yao; Xiong, Xian-Ze; Zhou, Rong-Xing; Deng, Yi-Lei; Jin, Yan-Wen; Lu, Jiong; Li, Fu-Yu; Cheng, Nan-Sheng

    2016-12-28

    To evaluate the feasibility of repairing a common bile duct defect with a decellularized ureteral graft in a porcine model. Eighteen pigs were randomly divided into three groups. An approximately 1 cm segment of the common bile duct was excised from all the pigs. The defect was repaired using a 2 cm long decellularized ureteral graft over a T-tube (T-tube group, n = 6) or a silicone stent (stent group, n = 6). Six pigs underwent bile duct reconstruction with a graft alone (stentless group). The surviving animals were euthanized at 3 mo. Specimens of the common bile ducts were obtained for histological analysis. The animals in the T-tube and stent groups survived until sacrifice. The blood test results were normal in both groups. The histology results showed a biliary epithelial layer covering the neo-bile duct. In contrast, all the animals in the stentless group died due to biliary peritonitis and cholangitis within two months post-surgery. Neither biliary epithelial cells nor accessory glands were observed at the graft sites in the stentless group. Repair of a common bile duct defect with a decellularized ureteral graft appears to be feasible. A T-tube or intraluminal stent was necessary to reduce postoperative complications.

  11. Hereditary Disorders with Defective Repair of UV-Induced DNA Damage

    Directory of Open Access Journals (Sweden)

    Shinichi Moriwaki

    2013-01-01

    Full Text Available Nucleotide excision repair (NER is an essential system for correcting ultraviolet (UV–-induced DNA damage. Lesions remaining in DNA due to reduced capacity of NER may result in cellular death, premature aging, mutagenesis and carcinogenesis of the skin. So, NER is an important protection against these changes. There are three representative genodermatoses resulting from genetic defects in NER: xeroderma pigmentosum (XP, Cockayne syndrome (CS, and trichothiodystrophy (TTD. In Japan, CS is similarly rare but XP is more common and TTD is less common compared to Western countries. In 1998, we established the system for the diagnosis of these disorders and we have been performing DNA repair and genetic analysis for more than 400 samples since then. At present, there is no cure for any human genetic disorder. Early diagnosis and symptomatic treatment of neurological, ocular and dermatological abnormalities should contribute to prolonging life and elevating QOL in patients.

  12. A polymorphism in the base excision repair gene PARP2 is associated with differential prognosis by chemotherapy among postmenopausal breast cancer patients

    NARCIS (Netherlands)

    P. Seibold (Petra); P. Schmezer (Peter); T.W. Behrens (Timothy); K. Michailidou (Kyriaki); M.K. Bolla (Manjeet); Q. Wang (Qing); D. Flesch-Janys (Dieter); H. Nevanlinna (Heli); R. Fagerholm (Rainer); K. Aittomäki (Kristiina); C. Blomqvist (Carl); S. Margolin (Sara); A. Mannermaa (Arto); V. Kataja (Vesa); V-M. Kosma (Veli-Matti); J.M. Hartikainen (J.); D. Lambrechts (Diether); H. Wildiers (Hans); V. Kristensen (Vessela); G.G. Alnæs (Grethe Grenaker); S. Nord (Silje); A.-L. Borresen-Dale (Anne-Lise); M.J. Hooning (Maartje); A. Hollestelle (Antoinette); A. Jager (Agnes); C.M. Seynaeve (Caroline); J. Li (Jingmei); J. Liu (Jianjun); M.K. Humphreys (Manjeet); A.M. Dunning (Alison); V. Rhenius (Valerie); M. Shah (Mitul); M. Kabisch (Maria); D. Torres (Diana); H.U. Ulmer (Hans); U. Hamann (Ute); J.M. Schildkraut (Joellen M.); K.S. Purrington (Kristen S.); F.J. Couch (Fergus); P. Hall (Per); P.D.P. Pharoah (Paul); D.F. Easton (Douglas); M.K. Schmidt (Marjanka); J. Chang-Claude (Jenny); O. Popanda (Odilia)

    2015-01-01

    textabstractBackground: Personalized therapy considering clinical and genetic patient characteristics will further improve breast cancer survival. Two widely used treatments, chemotherapy and radiotherapy, can induce oxidative DNA damage and, if not repaired, cell death. Since base excision repair

  13. Polysulfide compounds as inhibitors of the key base excision repair enzymes

    Directory of Open Access Journals (Sweden)

    Salakhutdinov N. F.

    2012-06-01

    Full Text Available Aim. To increase the capacity of antitumor therapy based on DNA damage it is important to minimize the repair of DNA lesions that can be achieved by inhibiting the activity of key DNA repair enzymes. To this end several benzopentathiepine and benzo[1,3]dithiol derivatives were synthesized and tested as inhibitors of the key base excision repair (BER enzymes, PARP1, DNA polymerase β, and APE1. Methods. The procedure of synthesis of several new compounds was developed. The inhibitory capacity of the compounds was estimated by comparison of the enzyme activities in specific tests in the presence of compounds versus their absence. Results. Benzopentathiepine derivative bearing trifluoromethyl group at the 1st position was shown to be a weak inhibitor of PARP1. Cyclic substituents at the 1st position attached through amide bond bring about moderate enhancement of pol β inhibition. Each studied substituent at the 1st position considerably increases the inhibition of APE1-catalyzed hydrolysis of AP sites as compared to parent compound. Conclusions. Several new inhibitors of BER enzymes were revealed. The directions for further modification of compounds to improve their inhibitory activity were found out.

  14. Oxidative DNA damage background estimated by a system model of base excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Sokhansanj, B A; Wilson, III, D M

    2004-05-13

    Human DNA can be damaged by natural metabolism through free radical production. It has been suggested that the equilibrium between innate damage and cellular DNA repair results in an oxidative DNA damage background that potentially contributes to disease and aging. Efforts to quantitatively characterize the human oxidative DNA damage background level based on measuring 8-oxoguanine lesions as a biomarker have led to estimates varying over 3-4 orders of magnitude, depending on the method of measurement. We applied a previously developed and validated quantitative pathway model of human DNA base excision repair, integrating experimentally determined endogenous damage rates and model parameters from multiple sources. Our estimates of at most 100 8-oxoguanine lesions per cell are consistent with the low end of data from biochemical and cell biology experiments, a result robust to model limitations and parameter variation. Our results show the power of quantitative system modeling to interpret composite experimental data and make biologically and physiologically relevant predictions for complex human DNA repair pathway mechanisms and capacity.

  15. International congress on DNA damage and repair: Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    1987-01-01

    This document contains the abstracts of 105 papers presented at the Congress. Topics covered include the Escherichia coli nucleotide excision repair system, DNA repair in malignant transformations, defective DNA repair, and gene regulation. (TEM)

  16. A simple technique for repair of rectus sheath defects.

    Science.gov (United States)

    Asaadi, M; Haramis, H T

    1994-01-01

    Several approaches for repair of diastasis recti during abdominoplasty and repair of rectus sheath defect during transverse rectus abdominis musculocutaneous flap harvest have been described. Although these have generally been effective, we feel our procedure to be advantageous. The method presented is quick, easy, and efficient. In addition, because a looped (double), monofilament suture is used, a stronger, more aesthetic repair is accomplished. This technique has been used in 39 patients over a 25-month period. No recurrences of diastasis recti and no hernias have been observed. Furthermore, all patients remain without complaint.

  17. Structure of UvrA nucleotide excision repair protein in complex with modified DNA

    Science.gov (United States)

    Jaciuk, Marcin; Nowak, Elżbieta; Skowronek, Krzysztof; Tańska, Anna; Nowotny, Marcin

    2012-01-01

    One of the primary pathways for removal of DNA damage is nucleotide excision repair (NER). In bacteria, the UvrA protein is the component of NER that locates the lesion. A notable feature of NER is its ability to act on many DNA modifications that vary in chemical structure. So far, the mechanism underlying this broad specificity has been unclear. Here, we report the first crystal structure of a UvrA protein in complex with a chemically modified oligonucleotide. The structure shows that the UvrA dimer does not contact the site of lesion directly, but rather binds the DNA regions on both sides of the modification. The DNA region harboring the modification is deformed, with the double helix bent and unwound. UvrA uses damage-induced deformations of the DNA and a less rigid structure of the modified double helix for indirect readout of the lesion. PMID:21240268

  18. Enhanced base excision repair capacity in carotid atherosclerosis may protect nuclear DNA but not mitochondrial DNA

    DEFF Research Database (Denmark)

    Skarpengland, Tonje; B. Dahl, Tuva; Skjelland, Mona

    2016-01-01

    disease-free carotid specimens from patients with carotid plaques and 10 non-atherosclerotic control arteries. Genomic integrity, mitochondrial (mt) DNA copy number, oxidative DNA damage and BER proteins were evaluated in a subgroup of plaques and controls. Our major findings were: (i) The BER pathway...... genes in atherosclerosis may contribute to lesional nuclear DNA stability but appears insufficient to maintain mtDNA integrity, potentially influencing mitochondrial function in cells within the atherosclerotic lesion.......Lesional and systemic oxidative stress has been implicated in the pathogenesis of atherosclerosis, potentially leading to accumulation of DNA base lesions within atherosclerotic plaques. Although base excision repair (BER) is a major pathway counteracting oxidative DNA damage, our knowledge on BER...

  19. Repair of congenital heart defects associated with single pulmonary artery.

    Science.gov (United States)

    Bockeria, Leo A; Makhachev, Osman A; Khiriev, Titalav Kh; Podzolkov, Vladimir P; Zelenikin, Mikhail A; Kim, Aleksey I; Zaets, Sergey B

    2015-02-01

    Experience with complete repair of congenital heart defects associated with unilateral absence of a pulmonary artery is limited. The aim of this retrospective study was to present our surgical experience of this complex category of patients, to analyze immediate results of surgical interventions, and to suggest a rational surgical strategy. Of 37 patients with a single pulmonary artery who underwent complete repair of associated heart defects, the left or right pulmonary artery was absent in 32 and 5, respectively. The most frequent heart defects were tetralogy of Fallot (n = 25) and ventricular septal defect (n = 8). The median age of these patients was 7.1 years. Preoperative examinations included echocardiography, cardiac catheterization and angiocardiography, with quantitative assessment of the single pulmonary artery. In-hospital parameters of surgical outcome were analyzed. Recorded hospital mortality was 2.7% (1/37). The single death was in a patient with tetralogy of Fallot, agenesis of the left pulmonary artery, and a small diameter of the contralateral pulmonary artery (Nakata index 174 mm(2)·m(-2)). The right-to-left ventricular systolic pressure ratio after complete tetralogy of Fallot repair in patients who survived the operation was 0.58 ± 0.11. Complete repair of congenital heart defects in patients with unilateral absence of a pulmonary artery is associated with a relatively low risk. If the hilar artery is of adequate size, surgical intervention should attempt restoration of the communication between the disconnected hilar artery and the pulmonary trunk, in addition to repairing the heart defects. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  20. Nucleotide excision repair pathway assessment in DNA exposed to low-intensity red and infrared lasers.

    Science.gov (United States)

    Fonseca, A S; Campos, V M A; Magalhães, L A G; Paoli, F

    2015-10-01

    Low-intensity lasers are used for prevention and management of oral mucositis induced by anticancer therapy, but the effectiveness of treatment depends on the genetic characteristics of affected cells. This study evaluated the survival and induction of filamentation of Escherichia coli cells deficient in the nucleotide excision repair pathway, and the action of T4endonuclease V on plasmid DNA exposed to low-intensity red and near-infrared laser light. Cultures of wild-type (strain AB1157) E. coli and strain AB1886 (deficient in uvrA protein) were exposed to red (660 nm) and infrared (808 nm) lasers at various fluences, powers and emission modes to study bacterial survival and filamentation. Also, plasmid DNA was exposed to laser light to study DNA lesions produced in vitro by T4endonuclease V. Low-intensity lasers:i) had no effect on survival of wild-type E. coli but decreased the survival of uvrA protein-deficient cells,ii) induced bacterial filamentation, iii) did not alter the electrophoretic profile of plasmids in agarose gels, andiv) did not alter the electrophoretic profile of plasmids incubated with T4 endonuclease V. These results increase our understanding of the effects of laser light on cells with various genetic characteristics, such as xeroderma pigmentosum cells deficient in nucleotide excision pathway activity in patients with mucositis treated by low-intensity lasers.

  1. Nucleotide excision repair pathway assessment in DNA exposed to low-intensity red and infrared lasers

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, A.S.; Campos, V.M.A.; Magalhaes, L.A.G., E-mail: adnfonseca@ig.com.br [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria. Lab. de Ciencias Radiologicas; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Instituto de Ciencias Biologicas. Departamento de Morfologia

    2015-10-15

    Low-intensity lasers are used for prevention and management of oral mucositis induced by anticancer therapy, but the effectiveness of treatment depends on the genetic characteristics of affected cells. This study evaluated the survival and induction of filamentation of Escherichia coli cells deficient in the nucleotide excision repair pathway, and the action of T{sub 4} endonuclease V on plasmid DNA exposed to low-intensity red and near-infrared laser light. Cultures of wild-type (strain AB1157) E. coli and strain AB1886 (deficient in uvrA protein) were exposed to red (660 nm) and infrared (808 nm) lasers at various fluences, powers and emission modes to study bacterial survival and filamentation. Also, plasmid DNA was exposed to laser light to study DNA lesions produced in vitro by T{sub 4} endonuclease V. Low-intensity lasers: i) had no effect on survival of wild-type E. coli but decreased the survival of uvrA protein-deficient cells, ii) induced bacterial filamentation, iii) did not alter the electrophoretic profile of plasmids in agarose gels, and iv) did not alter the electrophoretic profile of plasmids incubated with T{sub 4} endonuclease V. These results increase our understanding of the effects of laser light on cells with various genetic characteristics, such as xeroderma pigmentosum cells deficient in nucleotide excision pathway activity in patients with mucositis treated by low-intensity lasers. (author)

  2. Molecular Cloning and 3D Structure Modeling of APEX1, DNA Base Excision Repair Enzyme from the Camel, Camelus dromedarius

    OpenAIRE

    Dalia Fouad; Hesham Mahmoud Saeed; Farid Shokry Ataya; Ajamaluddin Malik

    2012-01-01

    The domesticated one-humped camel, Camelus dromedarius, is one of the most important animals in the Arabian Desert. It is exposed most of its life to both intrinsic and extrinsic genotoxic factors that are known to cause gross DNA alterations in many organisms. Ionic radiation and sunlight are known producers of Reactive Oxygen Species (ROS), one of the causes for DNA lesions. The damaged DNA is repaired by many enzymes, among of them Base Excision Repair enzymes, produci...

  3. Exposure of Human Lung Cells to Tobacco Smoke Condensate Inhibits the Nucleotide Excision Repair Pathway.

    Directory of Open Access Journals (Sweden)

    Nathaniel Holcomb

    Full Text Available Exposure to tobacco smoke is the number one risk factor for lung cancer. Although the DNA damaging properties of tobacco smoke have been well documented, relatively few studies have examined its effect on DNA repair pathways. This is especially true for the nucleotide excision repair (NER pathway which recognizes and removes many structurally diverse DNA lesions, including those introduced by chemical carcinogens present in tobacco smoke. The aim of the present study was to investigate the effect of tobacco smoke on NER in human lung cells. We studied the effect of cigarette smoke condensate (CSC, a surrogate for tobacco smoke, on the NER pathway in two different human lung cell lines; IMR-90 lung fibroblasts and BEAS-2B bronchial epithelial cells. To measure NER, we employed a slot-blot assay to quantify the introduction and removal of UV light-induced 6-4 photoproducts and cyclobutane pyrimidine dimers. We find a dose-dependent inhibition of 6-4 photoproduct repair in both cell lines treated with CSC. Additionally, the impact of CSC on the abundance of various NER proteins and their respective RNAs was investigated. The abundance of XPC protein, which is required for functional NER, is significantly reduced by treatment with CSC while the abundance of XPA protein, also required for NER, is unaffected. Both XPC and XPA RNA levels are modestly reduced by CSC treatment. Finally, treatment of cells with MG-132 abrogates the reduction in the abundance of XPC protein produced by treatment with CSC, suggesting that CSC enhances proteasome-dependent turnover of the protein that is mediated by ubiquitination. Together, these findings indicate that tobacco smoke can inhibit the same DNA repair pathway that is also essential for the removal of some of the carcinogenic DNA damage introduced by smoke itself, increasing the DNA damage burden of cells exposed to tobacco smoke.

  4. Nucleotide Excision Repair and Vitamin D--Relevance for Skin Cancer Therapy.

    Science.gov (United States)

    Pawlowska, Elzbieta; Wysokinski, Daniel; Blasiak, Janusz

    2016-04-06

    Ultraviolet (UV) radiation is involved in almost all skin cancer cases, but on the other hand, it stimulates the production of pre-vitamin D3, whose active metabolite, 1,25-dihydroxyvitamin D3 (1,25VD3), plays important physiological functions on binding with its receptor (vitamin D receptor, VDR). UV-induced DNA damages in the form of cyclobutane pyrimidine dimers or (6-4)-pyrimidine-pyrimidone photoproducts are frequently found in skin cancer and its precursors. Therefore, removing these lesions is essential for the prevention of skin cancer. As UV-induced DNA damages are repaired by nucleotide excision repair (NER), the interaction of 1,25VD3 with NER components can be important for skin cancer transformation. Several studies show that 1,25VD3 protects DNA against damage induced by UV, but the exact mechanism of this protection is not completely clear. 1,25VD3 was also shown to affect cell cycle regulation and apoptosis in several signaling pathways, so it can be considered as a potential modulator of the cellular DNA damage response, which is crucial for mutagenesis and cancer transformation. 1,25VD3 was shown to affect DNA repair and potentially NER through decreasing nitrosylation of DNA repair enzymes by NO overproduction by UV, but other mechanisms of the interaction between 1,25VD3 and NER machinery also are suggested. Therefore, the array of NER gene functioning could be analyzed and an appropriate amount of 1.25VD3 could be recommended to decrease UV-induced DNA damage important for skin cancer transformation.

  5. EZH2 suppresses the nucleotide excision repair in nasopharyngeal carcinoma by silencing XPA gene.

    Science.gov (United States)

    Huang, Yuxiang; Wang, Xuanyi; Niu, Xiaoshuang; Wang, Xiaoshen; Jiang, Rui; Xu, Tingting; Liu, Yong; Liang, Liping; Ou, Xiaomin; Xing, Xing; Li, Weiwei; Hu, Chaosu

    2017-02-01

    The enhancer of zeste homolog 2 (EZH2) is involved in a number of fundamental pathological processes of cancer. However, its role in DNA repair pathway is still unclear. Here, we have identified XPA as a novel target gene of EZH2 via a DNA repair pathway PCR array. XPA plays a pivot role in nucleotide excision repair (NER). The expression of XPA was significantly increased by EZH2 specific inhibitor GSK126 or lentiviral shEZH2 in nasopharyngeal carcinoma (NPC) CNE and 8F cell lines. Chromatin immunoprecipitation assay demonstrated that EZH2 catalyzes H3K27 trimethylation at the XPA promoters. Furthermore, we validated the negative correlation of EZH2 and XPA in a NPC tissue microarray by immunohistochemistry staining. We also found that high expression of EZH2 was positively correlated with advanced T, N, and AJCC stage of NPC; and low expression of XPA was positively correlated with advanced T and N stage. In NPC cell lines, increased XPA expression by EZH2 inhibition resulted in a more rapid removal of UVC induced 6-4PP- and CPD-DNA adducts, as well as enhanced efficiency of DNA repair after UVC irradiation as detected by the Comet assay and immunofluorescence staining of γH2Ax. Consistently, increased cell clonogenic survival, decreased apoptosis, and necrosis after UVC irradiation, and increased resistance to DNA damaging agent cisplatin was also observed in EZH2 inhibited cells. These results illustrate that EZH2 may promote carcinogenesis and cancer development of NPC by transcriptional repression of XPA gene and inactivation of NER pathway. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Hemolytic anemia after atrioventricular septal defect repair without synthetic material.

    Science.gov (United States)

    Tsang, J C; Shum-Tim, D; Tchervenkov, C I; Jutras, L; Sinclair, B

    1999-11-01

    We report a rare case of severe hemolytic anemia following repair of a congenital heart defect without the use of prosthetic material. A review of the literature, diagnosis, and management are described. Although this is an unusual complication following congenital heart surgery, a high index of suspicion must be maintained and a possible mechanical cause should be sought and corrected.

  7. Repair of osteochondral defects with allogeneic tissue engineered cartilage implants.

    Science.gov (United States)

    Schreiber, R E; Ilten-Kirby, B M; Dunkelman, N S; Symons, K T; Rekettye, L M; Willoughby, J; Ratcliffe, A

    1999-10-01

    The objective of this study was to evaluate the effect of allogeneic tissue engineered cartilage implants on healing of osteochondral defects. Rabbit chondrocytes were cultured in monolayer, then seeded onto biodegradable, three-dimensional polyglycolic acid meshes. Cartilage constructs were cultured hydrodynamically to yield tissue with relatively more (mature) or less (immature) hyalinelike cartilage, as compared with adult rabbit articular cartilage. Osteochondral defects in the patellar grooves of both stifle joints either were left untreated or implanted with allogeneic tissue engineered cartilage. Histologic samples from in and around the defect sites were examined 3, 6, 9, and 12, and 24 months after surgery. By 9 months after surgery, defects sites treated with cartilage implants contained significantly greater amounts of hyalinelike cartilage with high levels of proteoglycan, and had a smooth, nonfibrillated articular surface as compared to untreated defects. In contrast, the repair tissue formed in untreated defects had fibrillated articular surfaces, significant amounts of fibrocartilage, and negligible proteoglycan. These differences between treated and untreated defects persisted through 24 months after surgery. The results of this study suggest that the treatment of osteochondral lesions with allogenic tissue engineered cartilage implants may lead to superior repair tissue than that found in untreated osteochondral lesions.

  8. Recruitment of the nucleotide excision repair endonuclease XPG to sites of UV-induced DNA damage depends on functional TFIIH

    NARCIS (Netherlands)

    A. Zotter (Angelika); A.B. Houtsmuller (Adriaan); M.S. Luijsterburg (Martijn); D.O. Warmerdam (Daniël); S.M. Ibrahim (Shehu); A.L. Nigg (Alex); W.A. van Cappellen (Gert); J.H.J. Hoeijmakers (Jan); R. van Driel; W. Vermeulen (Wim)

    2006-01-01

    textabstractThe structure-specific endonuclease XPG is an indispensable core protein of the nucleotide excision repair (NER) machinery. XPG cleaves the DNA strand at the 3′ side of the DNA damage. XPG binding stabilizes the NER preincision complex and is essential for the 5′ incision by the

  9. Polymorphisms in nucleotide excision repair genes, smoking and intake of fruit and vegetables in relation to lung cancer

    DEFF Research Database (Denmark)

    Raaschou-Nielsen, Ole; Sørensen, Mette; Overvad, Kim

    2007-01-01

    in the XPC, XPA and XPD genes involved in the nucleotide excision DNA repair pathway and analysed possible interactions with smoking and dietary intake of fruit and vegetables in relation to risk for lung cancer. We found that intake of fruit was associated with lower risk for lung cancer only among carriers...

  10. Coupling of Human DNA Excision Repair and the DNA Damage Checkpoint in a Defined in Vitro System*

    Science.gov (United States)

    Lindsey-Boltz, Laura A.; Kemp, Michael G.; Reardon, Joyce T.; DeRocco, Vanessa; Iyer, Ravi R.; Modrich, Paul; Sancar, Aziz

    2014-01-01

    DNA repair and DNA damage checkpoints work in concert to help maintain genomic integrity. In vivo data suggest that these two global responses to DNA damage are coupled. It has been proposed that the canonical 30 nucleotide single-stranded DNA gap generated by nucleotide excision repair is the signal that activates the ATR-mediated DNA damage checkpoint response and that the signal is enhanced by gap enlargement by EXO1 (exonuclease 1) 5′ to 3′ exonuclease activity. Here we have used purified core nucleotide excision repair factors (RPA, XPA, XPC, TFIIH, XPG, and XPF-ERCC1), core DNA damage checkpoint proteins (ATR-ATRIP, TopBP1, RPA), and DNA damaged by a UV-mimetic agent to analyze the basic steps of DNA damage checkpoint response in a biochemically defined system. We find that checkpoint signaling as measured by phosphorylation of target proteins by the ATR kinase requires enlargement of the excision gap generated by the excision repair system by the 5′ to 3′ exonuclease activity of EXO1. We conclude that, in addition to damaged DNA, RPA, XPA, XPC, TFIIH, XPG, XPF-ERCC1, ATR-ATRIP, TopBP1, and EXO1 constitute the minimum essential set of factors for ATR-mediated DNA damage checkpoint response. PMID:24403078

  11. Nucleotide excision repair at the single-molecule level : analysis of the E. coli UvrA protein

    NARCIS (Netherlands)

    Wagner, Koen

    2011-01-01

    In this thesis, the characteristics of the Escherichia coli UvrA protein were analyzed with microscopy techniques that allow detection of protein complexes at the single-molecule level. Together with UvrB and UvrC, UvrA catalyzes the excision of damaged DNA from the bacterial genome. This DNA repair

  12. Cloning, comparative mapping, and RNA expression of the mouse homologues of the Saccharomyces cerevisiae nucleotide excision repair gene RAD23

    Energy Technology Data Exchange (ETDEWEB)

    Spek, P.J. van der; Visser, C.E.; Bootsma, D. [Erasmus Univ., Rotterdam (Netherlands)] [and others

    1996-01-01

    The Saccharomyces cerevisiae RAD23 gene is involved in nucleotide excision repair (NER). Two human homologs of RAD23, HHR23A and HHR23B (HGMW-approved symbols RAD23A and RAD23B), were previously isolated. The HHR23B protein is complexed with the protein defective in the cancer-prone repair syndrome xeroderma pigmentosum, complementation group C, and is specifically involved in the global genome NER subpathway. The cloning of both mouse homologs (designated MHR23A and MHR23B) and detailed sequence comparison permitted the deduction of the following overall structure for all RAD23 homologs: an ubiquitin-like N-terminus followed by a strongly conserved 50-amino-acid domain that is repeated at the C-terminus. We also found this domain as a specific C-terminal extension of one of the ubiquitin-conjugating enzymes, providing a second link with the ubiquitin pathway. By means of in situ hybridization, MHR23A was assigned to mouse chromosome 8C3 and MHR23B to 4B3. Because of the close chromosomal proximity of human XPC and HHR23B, the mouse XPC chromosomal location was determined (6D). Physical disconnection of the genes in mouse argues against a functional significance of the colocalization of these genes in human. Northern blot analysis revealed constitutive expression of both MHR23 genes in all tissues examined. Elevated RNA expression of both MHR23 genes was observed in testis. Although the RAD23 equivalents are well conserved during evolution, the mammalian genes did not express the UV-inducible phenotype of their yeast counterpart. This may point to a fundamental difference between the UV responses of yeast and human. No stage-specific mRNA expression during the cell cycle was observed for the mammalian RAD23 homologs. 38 refs., 5 figs.

  13. Effects of post mortem interval and gender in DNA base excision repair activities in rat brains

    Energy Technology Data Exchange (ETDEWEB)

    Soltys, Daniela Tathiana; Pereira, Carolina Parga Martins; Ishibe, Gabriela Naomi; Souza-Pinto, Nadja Cristhina de, E-mail: nadja@iq.usp.br

    2015-06-15

    Most human tissues used in research are of post mortem origin. This is the case for all brain samples, and due to the difficulty in obtaining a good number of samples, especially in the case of neurodegenerative diseases, male and female samples are often included in the same experimental group. However, the effects of post mortem interval (PMI) and gender differences in the endpoints being analyzed are not always fully understood, as is the case for DNA repair activities. To investigate these effects, in a controlled genetic background, base excision repair (BER) activities were measured in protein extracts obtained from Wistar rat brains from different genders and defined PMI up to 24 hours, using a novel fluorescent-based in vitro incision assay. Uracil and AP-site incision activity in nuclear and mitochondrial extracts were similar in all groups included in this study. Our results show that gender and PMI up to 24 hours have no influence in the activities of the BER proteins UDG and APE1 in rat brains. These findings demonstrate that these variables do not interfere on the BER activities included in these study, and provide a security window to work with UDG and APE1 proteins in samples of post mortem origin.

  14. PARP-1 enhances the mismatch-dependence of 5′-directed excision in human mismatch repair in vitro

    Science.gov (United States)

    Liu, Yiyong; Kadyrov, Farid A.; Modrich, Paul

    2011-01-01

    End-directed mismatch-provoked excision has been reconstituted in several purified systems. While 3′-directed excision displays a mismatch dependence similar to that observed in nuclear extracts (≈ 20-fold), the mismatch dependence of 5′-directed excision is only 3 to 4-fold, significantly less than that in extracts (8 to 10-fold). Utilizing a fractionation-based approach, we have isolated a single polypeptide that enhances mismatch dependence of reconstituted 5′-directed excision and have shown it to be identical to poly[ADP-ribose] polymerase 1 (PARP-1). Titration of reconstituted excision reactions or PARP-1-depleted HeLa nuclear extract with purified PARP-1 showed that the protein specifically enhances mismatch dependence of 5′-directed excision. Analysis of a set of PARP-1 mutants revealed that the DNA binding domain and BRCT fold contribute to the regulation of excision specificity. Involvement of the catalytic domain is restricted to its ability to poly(ADP-ribosyl)ate PARP-1 in the presence of NAD+, likely through interference with DNA binding. Analysis of protein-protein interactions demonstrated that PARP-1 interacts with mismatch repair proteins MutSα, exonuclease 1, replication protein A (RPA), and as previously shown by others, replication factor C (RFC) and proliferating cell nuclear antigen (PCNA) as well. The BRCT fold plays an important role in the interaction of PARP-1 with the former three proteins. PMID:21945626

  15. Cloning of a human homolog of the yeast nucleotide excision repair gene MMS19 and interaction with transcription repair factor TFIIH via the XPB and XPD helicases

    NARCIS (Netherlands)

    T. Seroz; G.S. Winkler (Sebastiaan); J. Auriol; R.A. Verhage; W. Vermeulen (Wim); B. Smit (Bep); J. Brouwer (Jaap); G. Weeda (Geert); J.H.J. Hoeijmakers (Jan); A.P.M. Eker (André); J-M. Egly (Jean-Marc)

    2000-01-01

    textabstractNucleotide excision repair (NER) removes UV-induced photoproducts and numerous other DNA lesions in a highly conserved 'cut-and-paste' reaction that involves approximately 25 core components. In addition, several other proteins have been identified which are dispensable for NER in vitro

  16. Molecular characterization of the human excision repair gene ERCC-1: cDNA cloning and aminoacid homology with the yeast DNA repair gene RAD10.

    NARCIS (Netherlands)

    M. van Duin (Mark); J. de Wit (Jan); H. Odijk (Hanny); A. Westerveld (Andries); A. Yasui (Akira); M.H.M. Koken (Marcel); J.H.J. Hoeijmakers (Jan); D. Bootsma (Dirk)

    1986-01-01

    textabstractThe human excision repair gene ERCC-7 was cloned after DNA mediated gene transfer to the CHO mutant 43-38, which is sensitive to ultraviolet light and mitomycin-C. We describe the cloning and sequence analysis of the ERCC-7 cDNA and partial characterization of the gene. ERCC.1 has a size

  17. Decreased nucleotide excision repair in steatotic livers associates with myeloperoxidase-immunoreactivity

    Energy Technology Data Exchange (ETDEWEB)

    Schults, Marten A.; Nagle, Peter W. [Department of Toxicology, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Rensen, Sander S. [Department of Surgery, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Godschalk, Roger W. [Department of Toxicology, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Munnia, Armelle; Peluso, Marco [Cancer Risk Factor Branch, ISPO Cancer Prevention and Research Institute, Via Cosimo il Vecchio 2, 50139 Florence (Italy); Claessen, Sandra M. [Department of Toxicogenomics, GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Greve, Jan W. [Department of Surgery, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Driessen, Ann [Department of Pathology, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Verdam, Froukje J.; Buurman, Wim A. [Department of Surgery, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Schooten, Frederik J. van [Department of Toxicology, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands); Chiu, Roland K., E-mail: r.k.chiu@med.umcg.nl [Department of Toxicology, NUTRIM-School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht (Netherlands)

    2012-08-01

    Chronic inflammation is characterized by the influx of neutrophils and is associated with an increased production of reactive oxygen species that can damage DNA. Oxidative DNA damage is generally thought to be involved in the increased risk of cancer in inflamed tissues. We previously demonstrated that activated neutrophil mediated oxidative stress results in a reduction in nucleotide excision repair (NER) capacity, which could further enhance mutagenesis. Inflammation and oxidative stress are critical factors in the progression of nonalcoholic fatty liver disease that is linked with enhanced liver cancer risk. In this report, we therefore evaluated the role of neutrophils and the associated oxidative stress in damage recognition and DNA repair in steatotic livers of 35 severely obese subjects with either nonalcoholic steatohepatitis (NASH) (n = 17) or steatosis alone (n = 18). The neutrophilic influx in liver was assessed by myeloperoxidase (MPO) staining and the amount of oxidative DNA damage by measuring M{sub 1}dG adducts. No differences in M{sub 1}dG adduct levels were observed between patients with or without NASH and also not between individuals with high or low MPO immunoreactivity. However, we found that high expression of MPO in the liver, irrespective of disease status, reduced the damage recognition capacity as determined by staining for histone 2AX phosphorylation ({gamma}H2AX). This reduction in {gamma}H2AX formation in individuals with high MPO immunoreactivity was paralleled by a significant decrease in NER capacity as assessed by a functional repair assay, and was not related to cell proliferation. Thus, the observed reduction in NER capacity upon hepatic inflammation is associated with and may be a consequence of reduced damage recognition. These findings suggest a novel mechanism of liver cancer development in patients with nonalcoholic fatty liver disease.

  18. A Novel Esthetic Approach using Connective Tissue Graft for Soft Tissue Defect Following Surgical Excision of Gingival Fibrolipoma.

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    Balasundaram, Aruna; Parthasarathy, Harinath; Kumar, Praveenkrishna; Gajendran, Priyalochana; Appukuttan, Devapriya

    2014-11-01

    The aim of the present case report is to evaluate the adjunctive use of a connective tissue graft to overcome soft tissue defects following excision of a gingival fibrolipoma in the aesthetic region. Connective tissue graft has been well documented for treating defects of esthetic concern. However, the literature does not contain many reports on the esthetic clinical outcome following the use of connective tissue graft secondary to excision of soft tissue tumours. A 28-year-old male patient reported with a complaint of a recurrent growth in relation to his lower front tooth region. The lesion which was provisionally diagnosed as fibroma was treated with a complete surgical excision, following which a modified coronally advanced flap and connective tissue graft was adopted to overcome the soft tissue defect. The excised growth was diagnosed histologically as fibrolipoma. One year follow up showed no recurrence of the lesion and good esthetics.The adjunctive use of the connective tissue graft and modified coronally advanced flap predictably yields optimal soft tissue fill and excellent esthetics. Hence, routine use of this procedure may be recommended for surgical excision of soft tissue growths in esthetically sensitive areas.

  19. Nucleotide excision repair, mismatch repair, and R-loops modulate convergent transcription-induced cell death and repeat instability.

    Directory of Open Access Journals (Sweden)

    Yunfu Lin

    Full Text Available Expansion of CAG•CTG tracts located in specific genes is responsible for 13 human neurodegenerative disorders, the pathogenic mechanisms of which are not yet well defined. These disease genes are ubiquitously expressed in human tissues, and transcription has been identified as one of the major pathways destabilizing the repeats. Transcription-induced repeat instability depends on transcription-coupled nucleotide excision repair (TC-NER, the mismatch repair (MMR recognition component MSH2/MSH3, and RNA/DNA hybrids (R-loops. Recently, we reported that simultaneous sense and antisense transcription-convergent transcription-through a CAG repeat not only promotes repeat instability, but also induces a cell stress response, which arrests the cell cycle and eventually leads to massive cell death via apoptosis. Here, we use siRNA knockdowns to investigate whether NER, MMR, and R-loops also modulate convergent-transcription-induced cell death and repeat instability. We find that siRNA-mediated depletion of TC-NER components increases convergent transcription-induced cell death, as does the simultaneous depletion of RNase H1 and RNase H2A. In contrast, depletion of MSH2 decreases cell death. These results identify TC-NER, MMR recognition, and R-loops as modulators of convergent transcription-induced cell death and shed light on the molecular mechanism involved. We also find that the TC-NER pathway, MSH2, and R-loops modulate convergent transcription-induced repeat instability. These observations link the mechanisms of convergent transcription-induced repeat instability and convergent transcription-induced cell death, suggesting that a common structure may trigger both outcomes.

  20. PARP10 deficiency manifests by severe developmental delay and DNA repair defect.

    Science.gov (United States)

    Shahrour, Maher Awni; Nicolae, Claudia M; Edvardson, Simon; Ashhab, Motee; Galvan, Adri M; Constantin, Daniel; Abu-Libdeh, Bassam; Moldovan, George-Lucian; Elpeleg, Orly

    2016-10-01

    DNA repair mechanisms such as nucleotide excision repair (NER) and translesion synthesis (TLS) are dependent on proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory protein. Recently, homozygosity for p.Ser228Ile mutation in the PCNA gene was reported in patients with neurodegeneration and impaired NER. Using exome sequencing, we identified a homozygous deleterious mutation, c.648delAG, in the PARP10 gene, in a patient suffering from severe developmental delay. In agreement, PARP10 protein was absent from the patient cells. We have previously shown that PARP10 is recruited by PCNA to DNA damage sites and is required for DNA damage resistance. The patient cells were significantly more sensitive to hydroxyurea and UV-induced DNA damage than control cells, resulting in increased apoptosis, indicating DNA repair impairment in the patient cells. PARP10 deficiency joins the long list of DNA repair defects associated with neurodegenerative disorders, including ataxia telangiectasia, xeroderma pigmentosum, Cockayne syndrome, and the recently reported PCNA mutation.

  1. Stem Cells from Deciduous Tooth Repair Mandibular Defect in Swine

    Science.gov (United States)

    Zheng, Y.; Liu, Y.; Zhang, C.M.; Zhang, H.Y.; Li, W.H.; Shi, S.; Le, A.D.; Wang, S.L.

    2009-01-01

    Stem cells from human exfoliated deciduous teeth have been identified as a new post-natal stem cell population with multipotential differentiation capabilities, including regeneration of mineralized tissues in vivo. To examine the efficacy of utilizing these stem cells in regenerating orofacial bone defects, we isolated stem cells from miniature pig deciduous teeth and engrafted the critical-size bone defects generated in swine mandible models. Our results indicated that stem cells from miniature pig deciduous teeth, an autologous and easily accessible stem cell source, were able to engraft and regenerate bone to repair critical-size mandibular defects at 6 months post-surgical reconstruction. This pre-clinical study in a large-animal model, specifically swine, allows for testing of a stem cells/scaffold construct in the restoration of orofacial skeletal defects and provides rapid translation of stem-cell-based therapy in orofacial reconstruction in human clinical trials. PMID:19329459

  2. Stem cells from deciduous tooth repair mandibular defect in swine.

    Science.gov (United States)

    Zheng, Y; Liu, Y; Zhang, C M; Zhang, H Y; Li, W H; Shi, S; Le, A D; Wang, S L

    2009-03-01

    Stem cells from human exfoliated deciduous teeth have been identified as a new post-natal stem cell population with multipotential differentiation capabilities, including regeneration of mineralized tissues in vivo. To examine the efficacy of utilizing these stem cells in regenerating orofacial bone defects, we isolated stem cells from miniature pig deciduous teeth and engrafted the critical-size bone defects generated in swine mandible models. Our results indicated that stem cells from miniature pig deciduous teeth, an autologous and easily accessible stem cell source, were able to engraft and regenerate bone to repair critical-size mandibular defects at 6 months post-surgical reconstruction. This pre-clinical study in a large-animal model, specifically swine, allows for testing of a stem cells/scaffold construct in the restoration of orofacial skeletal defects and provides rapid translation of stem-cell-based therapy in orofacial reconstruction in human clinical trials.

  3. Oxidatively damaged DNA repair defect in cockayne syndrome and its complementation by heterologous repair proteins.

    Science.gov (United States)

    Frosina, Guido

    2008-01-01

    Cockayne syndrome (complementation groups A and B) is a rare autosomal recessive DNA repair disorder characterized by photosensitive skin and severely impaired physical and intellectual development. The Cockayne syndrome A and B proteins intervene in the repair of DNA modifications that block the RNA polymerase in transcribed DNA sequences (transcription-coupled repair). Recent results suggest that they also have a more general role in the repair of oxidative DNA base modifications. Although the phenotypical consequences of defective repair of oxidatively damaged DNA in Cockayne syndrome are not determined, accumulation of oxidized lesions might contribute to delay the physical and intellectual development of these patients. To conceive new therapeutic strategies for this syndrome, we are investigating whether the oxidatively damaged DNA repair defect in Cockayne syndrome might be complemented by heterologous repair proteins, such as the Escherichia coli formamidopyrimidine-DNA glycosylase and endonuclease III. The complementation studies may shed light on the important lesions for the Cockayne syndrome phenotype and offer new tools for future therapies aimed at counteracting the consequences of oxidatively damaged DNA accumulation.

  4. Decreased transcription-coupled nucleotide excision repair capacity is associated with increased p53- and MLH1-independent apoptosis in response to cisplatin

    Directory of Open Access Journals (Sweden)

    Smith Jennifer M

    2010-05-01

    Full Text Available Abstract Background One of the most commonly used classes of anti-cancer drugs presently in clinical practice is the platinum-based drugs, including cisplatin. The efficacy of cisplatin therapy is often limited by the emergence of resistant tumours following treatment. Cisplatin resistance is multi-factorial but can be associated with increased DNA repair capacity, mutations in p53 or loss of DNA mismatch repair capacity. Methods RNA interference (RNAi was used to reduce the transcription-coupled nucleotide excision repair (TC-NER capacity of several prostate and colorectal carcinoma cell lines with specific defects in p53 and/or DNA mismatch repair. The effect of small inhibitory RNAs designed to target the CSB (Cockayne syndrome group B transcript on TC-NER and the sensitivity of cells to cisplatin-induced apoptosis was determined. Results These prostate and colon cancer cell lines were initially TC-NER proficient and RNAi against CSB significantly reduced their DNA repair capacity. Decreased TC-NER capacity was associated with an increase in the sensitivity of tumour cells to cisplatin-induced apoptosis, even in p53 null and DNA mismatch repair-deficient cell lines. Conclusion The present work indicates that CSB and TC-NER play a prominent role in determining the sensitivity of tumour cells to cisplatin even in the absence of p53 and DNA mismatch repair. These results further suggest that CSB represents a potential target for cancer therapy that may be important to overcome resistance to cisplatin in the clinic.

  5. Repair of segmental bone defects in the maxilla by transport disc distraction osteogenesis: Clinical experience with a new device.

    Science.gov (United States)

    Boonzaier, James; Vicatos, George; Hendricks, Rushdi

    2015-01-01

    The bones of the maxillary complex are vital for normal oro-nasal function and facial cosmetics. Maxillary tumor excision results in large defects that commonly include segments of the alveolar and palatine processes, compromising eating, speech and facial appearance. Unlike the conventional approach to maxillary defect repair by vascularized bone grafting, transport disc distraction osteogenesis (TDDO) stimulates new bone by separating the healing callus, and stimulates growth of surrounding soft tissues as well. Bone formed in this way closely mimics the parent bone in form and internal structure, producing a superior anatomical, functional and cosmetic result. Historically, TDDO has been successfully used to close small horizontal cleft defects in the maxilla, not exceeding 25 mm. Fujioka et al. reported in 2012 that "no bone transporter corresponding to the (large) size of the oro-antral fistula is marketed. The authors report the successful treatment of 4 cases involving alveolar defects of between 25 mm and 80 mm in length.

  6. Stabilization of Ultraviolet (UV)-stimulated Scaffold Protein A by Interaction with Ubiquitin-specific Peptidase 7 Is Essential for Transcription-coupled Nucleotide Excision Repair*

    Science.gov (United States)

    Higa, Mitsuru; Zhang, Xue; Tanaka, Kiyoji; Saijo, Masafumi

    2016-01-01

    UV-sensitive syndrome is an autosomal recessive disorder characterized by hypersensitivity to UV light and deficiency in transcription-coupled nucleotide excision repair (TC-NER), a subpathway of nucleotide excision repair that rapidly removes transcription-blocking DNA damage. UV-sensitive syndrome consists of three genetic complementation groups caused by mutations in the CSA, CSB, and UVSSA genes. UV-stimulated scaffold protein A (UVSSA), the product of UVSSA, which is required for stabilization of Cockayne syndrome group B (CSB) protein and reappearance of the hypophosphorylated form of RNA polymerase II after UV irradiation, forms a complex with ubiquitin-specific peptidase 7 (USP7). In this study, we demonstrated that the deubiquitination activity of USP7 is suppressed by its interaction with UVSSA. The interaction required the tumor necrosis factor receptor-associated factor domain of USP7 and the central region of UVSSA and was disrupted by an amino acid substitution in the tumor necrosis factor receptor-associated factor-binding motif of UVSSA. Cells expressing mutant UVSSA were highly sensitive to UV irradiation and defective in recovery of RNA synthesis after UV irradiation. These results indicate that the interaction between UVSSA and USP7 is important for TC-NER. Furthermore, the mutant UVSSA was rapidly degraded by the proteasome, and CSB was also degraded after UV irradiation as observed in UVSSA-deficient cells. Thus, stabilization of UVSSA by interaction with USP7 is essential for TC-NER. PMID:27129218

  7. Metal inhibition of human N-methylpurine-DNA glycosylase activity in base excision repair.

    Science.gov (United States)

    Wang, Ping; Guliaev, Anton B; Hang, Bo

    2006-10-25

    Cadmium (Cd2+), nickel (Ni2+) and cobalt (Co2+) are human and/or animal carcinogens. Zinc (Zn2+) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd2+, Ni2+, and Zn2+ can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (varepsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1,000 microM, both Cd2+ and Zn2+ showed metal-dependent inhibition of the MPG catalytic activity. Ni2+ also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co2+ and Mg2+ did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the varepsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd2+, Zn2+, and Ni2+ at concentrations that show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn2+ showed that the MPG active site has a potential binding site for Zn2+, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.

  8. Intrinsic mitochondrial DNA repair defects in Ataxia Telangiectasia.

    Science.gov (United States)

    Sharma, Nilesh K; Lebedeva, Maria; Thomas, Terace; Kovalenko, Olga A; Stumpf, Jeffrey D; Shadel, Gerald S; Santos, Janine H

    2014-01-01

    Ataxia Telangiectasia (A-T) is a progressive childhood disorder characterized most notably by cerebellar degeneration and predisposition to cancer. A-T is caused by mutations in the kinase ATM, a master regulator of the DNA double-strand break response. In addition to DNA-damage signaling defects, A-T cells display mitochondrial dysfunction that is thought to contribute to A-T pathogenesis. However, the molecular mechanism leading to mitochondrial dysfunction in A-T remains unclear. Here, we show that lack of ATM leads to reduced mitochondrial DNA (mtDNA) integrity and mitochondrial dysfunction, which are associated to defective mtDNA repair. While protein levels of mtDNA repair proteins are essentially normal, in the absence of ATM levels specifically of DNA ligase III (Lig3), the only DNA ligase working in mitochondria is reduced. The reduction of Lig3 is observed in different A-T patient cells, in brain and pre-B cells derived from ATM knockout mice as well as upon transient or stable knockdown of ATM. Furthermore, pharmacological inhibition of Lig3 in wild type cells phenocopies the mtDNA repair defects observed in A-T patient cells. As targeted deletion of LIG3 in the central nervous system causes debilitating ataxia in mice, reduced Lig3 protein levels and the consequent mtDNA repair defect may contribute to A-T neurodegeneration. A-T is thus the first disease characterized by diminished Lig3. Published by Elsevier B.V.

  9. Site-specific analysis of UV-induced cyclobutane pyrimidine dimers in nucleotide excision repair-proficient and -deficient hamster cells: Lack of correlation with mutational spectra

    Energy Technology Data Exchange (ETDEWEB)

    Vreeswijk, Maaike P.G., E-mail: vreeswijk@lumc.nl [Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, P.O. Box 9600, Postzone S4-P, 2300 RC Leiden (Netherlands); Department of Human Genetics, Center for Human and Clinical Genetics, Leiden University Medical Center, Building 2, Postzone S-04, P.O. Box 9600, 2300 RC Leiden (Netherlands); Meijers, Caro M.; Giphart-Gassler, Micheline; Vrieling, Harry; Zeeland, Albert A. van; Mullenders, Leon H.F.; Loenen, Wil A.M. [Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, P.O. Box 9600, Postzone S4-P, 2300 RC Leiden (Netherlands)

    2009-04-26

    Irradiation of cells with UVC light induces two types of mutagenic DNA photoproducts, i.e. cyclobutane pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimidone photoproducts (6-4PP). To investigate the relationship between the frequency of UV-induced photolesions at specific sites and their ability to induce mutations, we quantified CPD formation at the nucleotide level along exons 3 and 8 of the hprt gene using ligation-mediated PCR, and determined the mutational spectrum of 132 UV-induced hprt mutants in the AA8 hamster cell line and of 165 mutants in its nucleotide excision repair-defective derivative UV5. In AA8 cells, transversions predominated with a strong strand bias towards thymine-containing photolesions in the non-transcribed strand. As hamster AA8 cells are proficient in global genome repair of 6-4PP but selectively repair CPD from the transcribed strand of active genes, most mutations probably resulted from erroneous bypass of CPD in the non-transcribed strand. However, the relative incidence of CPD and the positions where mutations most frequently arose do not correlate. In fact some major damage sites hardly gave rise to the formation of mutations. In the repair-defective UV5 cells, mutations were almost exclusively C > T transitions caused by photoproducts at PyC sites in the transcribed strand. Even though CPD were formed at high frequencies at some TT sites in UV5, these photoproducts did not contribute to mutation induction at all. We conclude that, even in the absence of repair, large variations in the level of induction of CPD at different sites throughout the two exons do not correspond to frequencies of mutation induction.

  10. APE1, the DNA base excision repair protein, regulates the removal of platinum adducts in sensory neuronal cultures by NER

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Suk [Department of Biochemistry and Molecular Biology, Indianapolis, IN 46202 (United States); Guo, Chunlu; Thompson, Eric L. [Department of Pharmacology and Toxicology, Indianapolis, IN 46202 (United States); Jiang, Yanlin [Department of Pediatrics and Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202 (United States); Kelley, Mark R. [Department of Biochemistry and Molecular Biology, Indianapolis, IN 46202 (United States); Department of Pharmacology and Toxicology, Indianapolis, IN 46202 (United States); Department of Pediatrics and Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202 (United States); Vasko, Michael R. [Department of Pharmacology and Toxicology, Indianapolis, IN 46202 (United States); Lee, Suk-Hee, E-mail: slee@iu.edu [Department of Biochemistry and Molecular Biology, Indianapolis, IN 46202 (United States)

    2015-09-15

    Peripheral neuropathy is one of the major side effects of treatment with the anticancer drug, cisplatin. One proposed mechanism for this neurotoxicity is the formation of platinum adducts in sensory neurons that could contribute to DNA damage. Although this damage is largely repaired by nuclear excision repair (NER), our previous findings suggest that augmenting the base excision repair pathway (BER) by overexpressing the repair protein APE1 protects sensory neurons from cisplatin-induced neurotoxicity. The question remains whether APE1 contributes to the ability of the NER pathway to repair platinum-damage in neuronal cells. To examine this, we manipulated APE1 expression in sensory neuronal cultures and measured Pt-removal after exposure to cisplatin. When neuronal cultures were treated with increasing concentrations of cisplatin for two or three hours, there was a concentration-dependent increase in Pt-damage that peaked at four hours and returned to near baseline levels after 24 h. In cultures where APE1 expression was reduced by ∼80% using siRNA directed at APE1, there was a significant inhibition of Pt-removal over eight hours which was reversed by overexpressing APE1 using a lentiviral construct for human wtAPE1. Overexpressing a mutant APE1 (C65 APE1), which only has DNA repair activity, but not its other significant redox-signaling function, mimicked the effects of wtAPE1. Overexpressing DNA repair activity mutant APE1 (226 + 177APE1), with only redox activity was ineffective suggesting it is the DNA repair function of APE1 and not its redox-signaling, that restores the Pt-damage removal. Together, these data provide the first evidence that a critical BER enzyme, APE1, helps regulate the NER pathway in the repair of cisplatin damage in sensory neurons.

  11. Crystal structure of the FeS cluster-containing nucleotide excision repair helicase XPD.

    Directory of Open Access Journals (Sweden)

    Stefanie C Wolski

    2008-06-01

    Full Text Available DNA damage recognition by the nucleotide excision repair pathway requires an initial step identifying helical distortions in the DNA and a proofreading step verifying the presence of a lesion. This proofreading step is accomplished in eukaryotes by the TFIIH complex. The critical damage recognition component of TFIIH is the XPD protein, a DNA helicase that unwinds DNA and identifies the damage. Here, we describe the crystal structure of an archaeal XPD protein with high sequence identity to the human XPD protein that reveals how the structural helicase framework is combined with additional elements for strand separation and DNA scanning. Two RecA-like helicase domains are complemented by a 4Fe4S cluster domain, which has been implicated in damage recognition, and an alpha-helical domain. The first helicase domain together with the helical and 4Fe4S-cluster-containing domains form a central hole with a diameter sufficient in size to allow passage of a single stranded DNA. Based on our results, we suggest a model of how DNA is bound to the XPD protein, and can rationalize several of the mutations in the human XPD gene that lead to one of three severe diseases, xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy.

  12. Conservation of the nucleotide excision repair pathway: characterization of hydra Xeroderma Pigmentosum group F homolog.

    Directory of Open Access Journals (Sweden)

    Apurva Barve

    Full Text Available Hydra, one of the earliest metazoans with tissue grade organization and nervous system, is an animal with a remarkable regeneration capacity and shows no signs of organismal aging. We have for the first time identified genes of the nucleotide excision repair (NER pathway from hydra. Here we report cloning and characterization of hydra homolog of xeroderma pigmentosum group F (XPF gene that encodes a structure-specific 5' endonuclease which is a crucial component of NER. In silico analysis shows that hydra XPF amino acid sequence is very similar to its counterparts from other animals, especially vertebrates, and shows all features essential for its function. By in situ hybridization, we show that hydra XPF is expressed prominently in the multipotent stem cell niche in the central region of the body column. Ectoderm of the diploblastic hydra was shown to express higher levels of XPF as compared to the endoderm by semi-quantitative RT-PCR. Semi-quantitative RT-PCR analysis also demonstrated that interstitial cells, a multipotent and rapidly cycling stem cell lineage of hydra, express higher levels of XPF mRNA than other cell types. Our data show that XPF and by extension, the NER pathway is highly conserved during evolution. The prominent expression of an NER gene in interstitial cells may have implications for the lack of senescence in hydra.

  13. Conservation of the nucleotide excision repair pathway: characterization of hydra Xeroderma Pigmentosum group F homolog.

    Science.gov (United States)

    Barve, Apurva; Ghaskadbi, Saroj; Ghaskadbi, Surendra

    2013-01-01

    Hydra, one of the earliest metazoans with tissue grade organization and nervous system, is an animal with a remarkable regeneration capacity and shows no signs of organismal aging. We have for the first time identified genes of the nucleotide excision repair (NER) pathway from hydra. Here we report cloning and characterization of hydra homolog of xeroderma pigmentosum group F (XPF) gene that encodes a structure-specific 5' endonuclease which is a crucial component of NER. In silico analysis shows that hydra XPF amino acid sequence is very similar to its counterparts from other animals, especially vertebrates, and shows all features essential for its function. By in situ hybridization, we show that hydra XPF is expressed prominently in the multipotent stem cell niche in the central region of the body column. Ectoderm of the diploblastic hydra was shown to express higher levels of XPF as compared to the endoderm by semi-quantitative RT-PCR. Semi-quantitative RT-PCR analysis also demonstrated that interstitial cells, a multipotent and rapidly cycling stem cell lineage of hydra, express higher levels of XPF mRNA than other cell types. Our data show that XPF and by extension, the NER pathway is highly conserved during evolution. The prominent expression of an NER gene in interstitial cells may have implications for the lack of senescence in hydra.

  14. Nrf1 CNC-bZIP protein promotes cell survival and nucleotide excision repair through maintaining glutathione homeostasis.

    Science.gov (United States)

    Han, Weinong; Ming, Mei; Zhao, Rui; Pi, Jingbo; Wu, Chunli; He, Yu-Ying

    2012-05-25

    Skin cancer is the most common cancer in the United States. Its major environmental risk factor is UVB radiation in sunlight. In response to UVB damage, epidermal keratinocytes activate a specific repair pathway, i.e. nucleotide excision repair, to remove UVB-induced DNA lesions. However, the regulation of UVB response is not fully understood. Here we show that the long isoform of the nuclear factor erythroid 2-related factor 1 (Nrf1, also called NFE2L1), a cytoprotective transcription factor critical for the expression of multiple antioxidant response element-dependent genes, plays an important role in the response of keratinocytes to UVB. Nrf1 loss sensitized keratinocytes to UVB-induced apoptosis by up-regulating the expression of the proapoptotic Bcl-2 family member Bik through reducing glutathione levels. Knocking down Bik reduced UVB-induced apoptosis in Nrf1-inhibited cells. In UVB-irradiated surviving cells, however, disruption of Nrf1 impaired nucleotide excision repair through suppressing the transcription of xeroderma pigmentosum C (XPC), a factor essential for initiating the global genome nucleotide excision repair by recognizing the DNA lesion and recruiting downstream factors. Nrf1 enhanced XPC expression by increasing glutathione availability but was independent of the transcription repressor of XPC. Adding XPC or glutathione restored the DNA repair capacity in Nrf1-inhibited cells. Finally, we demonstrate that Nrf1 levels are significantly reduced by UVB radiation in mouse skin and are lower in human skin tumors than in normal skin. These results indicate a novel role of Nrf1 in UVB-induced DNA damage repair and suggest Nrf1 as a tumor suppressor in the skin.

  15. Influence of some prostaglandins on DNA synthesis and DNA excision repair in mouse spleen cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Egg, D.; Altmann, H.; Guenther R.; Klein W.; Kocsis, F.

    1978-03-01

    In vitro experiments were performed on mouse spleen cells to establish possible influences of some naturally occurring prostaglandins on DNA synthesis and DNA excision repair. The prostaglandins A1, B1, E1, E2, and F2 alpha were tested in concentrations of lopg, 5 ng and 2.5 microgram per ml cell suspension. DNA synthesis was significantly increased by PgF2 alpha in all the three concentrations tested, while the other tested prostaglandins were essentially ineffective. DNA excision repair was significantly inhibited by PgE1 and PgE2 at 5 ng/ml and at 2.5 microgram/ml but increased by PgF2 alpha in the two lower concentrations. The rejoining of DNA-strand breaks after gamma-irradiation was slightly reduced by PgE1, PgE2 and PgF2 alpha at 2.5 microgram/ml.

  16. Role of Base Excision Repair (BER) in Transcription-associated Mutagenesis of Nutritionally Stressed Nongrowing Bacillus subtilis Cell Subpopulations.

    Science.gov (United States)

    Ambriz-Aviña, Verónica; Yasbin, Ronald E; Robleto, Eduardo A; Pedraza-Reyes, Mario

    2016-11-01

    Compelling evidence points to transcriptional processes as important factors contributing to stationary-phase associated mutagenesis. However, it has not been documented whether or not base excision repair mechanisms play a role in modulating mutagenesis under conditions of transcriptional derepression. Here, we report on a flow cytometry-based methodology that employs a fluorescent reporter system to measure at single-cell level, the occurrence of transcription-associated mutations in nutritionally stressed B. subtilis cultures. Using this approach, we demonstrate that (i) high levels of transcription correlates with augmented mutation frequency, and (ii) mutation frequency is enhanced in nongrowing population cells deficient for deaminated (Ung, YwqL) and oxidized guanine (GO) excision repair, strongly suggesting that accumulation of spontaneous DNA lesions enhance transcription-associated mutagenesis.

  17. Red meat and poultry intake, polymorphisms in the nucleotide excision repair and mismatch repair pathways and colorectal cancer risk

    Science.gov (United States)

    Joshi, Amit D.; Corral, Román; Siegmund, Kimberly D.; Haile, Robert W.; Le Marchand, Loïc; Martínez, Maria Elena; Ahnen, Dennis J.; Sandler, Robert S.; Lance, Peter; Stern, Mariana C.

    2009-01-01

    Diets high in red meat have been consistently associated with colorectal cancer (CRC) risk and may result in exposure to carcinogens that cause DNA damage [i.e polycyclic aromatic hydrocarbons, heterocyclic amines (HCAs) and N-nitroso compounds]. Using a family-based study, we investigated whether polymorphisms in the nucleotide excision repair (NER) (ERCC1 3′ untranslated region (UTR) G/T, XPD Asp312Asn and Lys751Gln, XPC intron 11 C/A, XPA 5′ UTR C/T, XPF Arg415Gln and XPG Asp1104His) and mismatch repair (MLH1 Ile219Val and MSH2 Gly322Asp) pathways modified the association with red meat and poultry intake. We tested for gene–environment interactions using case-only analyses (n = 577) and compared the results using case-unaffected sibling comparisons (n = 307 sibships). Increased risk of CRC was observed for intake of more than or equal to three servings per week of red meat [odds ratio (OR) = 1.8, 95% confidence interval (CI) = 1.3–2.5)] or high-temperature cooked red meat (OR = 1.6, 95% CI = 1.1–2.2). Intake of red meat heavily brown on the outside or inside increased CRC risk only among subjects who carried the XPD codon 751 Lys/Lys genotype (case-only interaction P = 0.006 and P = 0.001, respectively, for doneness outside or inside) or the XPD codon 312 Asp/Asp genotype (case-only interaction P = 0.090 and P < 0.001, respectively). These interactions were stronger for rectal cancer cases (heterogeneity test P = 0.002 for XPD Asp312Asn and P = 0.03 for XPD Lys751Gln) and remained statistically significant after accounting for multiple testing. Case-unaffected sibling analyses were generally supportive of the case-only results. These findings highlight the possible contribution of diets high in red meat to the formation of lesions that elicit the NER pathway, such as carcinogen-induced bulky adducts. PMID:19029193

  18. Neil3-dependent base excision repair regulates lipid metabolism and prevents atherosclerosis in Apoe-deficient mice

    DEFF Research Database (Denmark)

    Skarpengland, Tonje; Holm, Sverre; Scheffler, Katja

    2016-01-01

    an atherogenic lipid profile, increased hepatic triglyceride levels and attenuated macrophage cholesterol efflux capacity. Apoe-/- Neil3-/- mice showed marked alterations in several pathways affecting hepatic lipid metabolism, but no genotypic alterations in genome integrity or genome-wide accumulation...... of oxidative DNA damage. These results suggest a novel role for the DNA glycosylase Neil3 in atherogenesis in balancing lipid metabolism and macrophage function, potentially independently of genome-wide canonical base excision repair of oxidative DNA damage....

  19. Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ping; Guliaev, Anton B.; Hang, Bo

    2006-02-28

    Cadmium (Cd{sup 2+}), nickel (Ni{sup 2+}) and cobalt (Co{sup 2+}) are human and/or animal carcinogens. Zinc (Zn{sup 2+}) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (var epsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1000 {micro}M, both Cd{sup 2+} and Zn{sup 2+} showed metal-dependent inhibition of the MPG catalytic activity. Ni{sup 2+} also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co{sup 2+} and Mg{sup 2+} did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the var epsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd{sup 2+}, Zn{sup 2+}, and Ni{sup 2+} at concentrations that show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn{sup 2+} showed that the MPG active site has a potential binding site for Zn{sup 2+}, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.

  20. [Intraoperative transesophageal echocardiography in robotic perimembranous ventricular septal defect repair].

    Science.gov (United States)

    Wang, Yao; Gao, Chang-Qing; Wang, Gang; Shen, Yan-Song; Wang, Jia-Li; Xiao, Cang-Song; Yang, Ming

    2013-11-01

    To explore the role of intraoperative transesophageal echocardiography (TEE) in robotic perimembranous ventricular septal defect (VSD) repair. A retrospective analysis was conducted with intraoperative TEE data of 18 consecutive patients who underwent robotic perimembranous VSD repair from January 2009 to August 2012. (1) Before cardiopulmonary bypass (CPB), TEE was performed to document the anatomic types, numbers, and the size of VSD. The procedures were predetermined by the surgeon according to TEE information. (2) During the establishment of peripheral CPB, TEE was used to guide the placement of cannulae in inferior vena cava (IVC), superior vena cava (SVC), and ascending aorta (AAO). (3) After weaning from CPB, TEE was conducted to evaluate the effect of the procedure. (1) Accuracy of TEE was 100% for diagnosing the anatomic types of VSD. All the surgical procedures were performed based on the predetermined information. (2) Under TEE guidance, all the cannulae in the SVC, IVC and AAO were located in correct positions. (3) In all patients, TEE confirmed successful VSD repair. TEE is a useful tool in the assessment of robotic perimembranous VSD repair.

  1. Defective DNA repair mechanisms in prostate cancer: impact of olaparib

    Directory of Open Access Journals (Sweden)

    De Felice F

    2017-03-01

    Full Text Available Francesca De Felice,1 Vincenzo Tombolini,1 Francesco Marampon,2 Angela Musella,3 Claudia Marchetti3 1Department of Radiotherapy, Policlinico Umberto I, “Sapienza” University of Rome, Rome, 2Department of Biotechnological and Applied Clinical Sciences, Laboratory of Radiobiology, University of L’Aquila, L’Aquila, 3Department of Gynecological and Obstetrical Sciences and Urological Sciences, “Sapienza” University of Rome, Rome, Italy Abstract: The field of prostate oncology has continued to change dramatically. It has truly become a field that is intensely linked to molecular genetic alterations, especially DNA-repair defects. Germline breast cancer 1 gene (BRCA1 and breast cancer 2 gene (BRCA2 mutations are implicated in the highest risk of prostate cancer (PC predisposition and aggressiveness. Poly adenosine diphosphate ribose polymerase (PARP proteins play a key role in DNA repair mechanisms and represent a valid target for new therapies. Olaparib is an oral PARP inhibitor that blocks DNA repair pathway and coupled with BRCA mutated-disease results in tumor cell death. In phase II clinical trials, including patients with advanced castration-resistant PC, olaparib seems to be efficacious and well tolerated. Waiting for randomized phase III trials, olaparib should be considered as a promising treatment option for PC. Keywords: prostate cancer, metastatic disease, castration resistant, BRCA, DNA-repair, PARP, olaparib

  2. Alternative Excision Repair of Ultraviolet B- and C-Induced DNA Damage in Dormant and Developing Spores of Bacillus subtilis

    Science.gov (United States)

    Ramírez-Guadiana, Fernando H.; Barraza-Salas, Marcelo; Ramírez-Ramírez, Norma; Ortiz-Cortés, Mayte; Setlow, Peter

    2012-01-01

    The nucleotide excision repair (NER) and spore photoproduct lyase DNA repair pathways are major determinants of Bacillus subtilis spore resistance to UV radiation. We report here that a putative ultraviolet (UV) damage endonuclease encoded by ywjD confers protection to developing and dormant spores of B. subtilis against UV DNA damage. In agreement with its predicted function, a His6-YwjD recombinant protein catalyzed the specific incision of UV-irradiated DNA in vitro. The maximum expression of a reporter gene fusion to the ywjD opening reading frame occurred late in sporulation, and this maximal expression was dependent on the forespore-specific RNA polymerase sigma factor, σG. Although the absence of YwjD and/or UvrA, an essential protein of the NER pathway, sensitized developing spores to UV-C, this effect was lower when these cells were treated with UV-B. In contrast, UV-B but not UV-C radiation dramatically decreased the survival of dormant spores deficient in both YwjD and UvrA. The distinct range of lesions generated by UV-C and UV-B and the different DNA photochemistry in developing and dormant spores may cause these differences. We postulate that in addition to the UvrABC repair system, developing and dormant spores of B. subtilis also rely on an alternative excision repair pathway involving YwjD to deal with the deleterious effects of various UV photoproducts. PMID:22961846

  3. NDR1 modulates the UV-induced DNA-damage checkpoint and nucleotide excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong-Min; Choi, Ji Ye [Department of Biological Science, Dong-A University, Busan (Korea, Republic of); Yi, Joo Mi [Research Center, Dongnam Institute of Radiological & Medical Sciences, Busan (Korea, Republic of); Chung, Jin Woong; Leem, Sun-Hee; Koh, Sang Seok [Department of Biological Science, Dong-A University, Busan (Korea, Republic of); Kang, Tae-Hong, E-mail: thkang@dau.ac.kr [Department of Biological Science, Dong-A University, Busan (Korea, Republic of)

    2015-06-05

    Nucleotide excision repair (NER) is the sole mechanism of UV-induced DNA lesion repair in mammals. A single round of NER requires multiple components including seven core NER factors, xeroderma pigmentosum A–G (XPA–XPG), and many auxiliary effector proteins including ATR serine/threonine kinase. The XPA protein helps to verify DNA damage and thus plays a rate-limiting role in NER. Hence, the regulation of XPA is important for the entire NER kinetic. We found that NDR1, a novel XPA-interacting protein, modulates NER by modulating the UV-induced DNA-damage checkpoint. In quiescent cells, NDR1 localized mainly in the cytoplasm. After UV irradiation, NDR1 accumulated in the nucleus. The siRNA knockdown of NDR1 delayed the repair of UV-induced cyclobutane pyrimidine dimers in both normal cells and cancer cells. It did not, however, alter the expression levels or the chromatin association levels of the core NER factors following UV irradiation. Instead, the NDR1-depleted cells displayed reduced activity of ATR for some set of its substrates including CHK1 and p53, suggesting that NDR1 modulates NER indirectly via the ATR pathway. - Highlights: • NDR1 is a novel XPA-interacting protein. • NDR1 accumulates in the nucleus in response to UV irradiation. • NDR1 modulates NER (nucleotide excision repair) by modulating the UV-induced DNA-damage checkpoint response.

  4. Defective transcription-coupled repair in Cockayne syndrome B mice is associated with skin cancer predisposition.

    NARCIS (Netherlands)

    G.T.J. van der Horst (Gijsbertus); H. van Steeg (Harry); R.J.W. Berg (Rob); A.J. van Gool (Alain); J. de Wit (Jan); G. Weeda (Geert); H. Morreau (Hans); R.B. Beems (Rudolf); C.F. van Kreijl (Coen); F.R. de Gruijl (Frank); D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1997-01-01

    textabstractA mouse model for the nucleotide excision repair disorder Cockayne syndrome (CS) was generated by mimicking a truncation in the CSB(ERCC6) gene of a CS-B patient. CSB-deficient mice exhibit all of the CS repair characteristics: ultraviolet (UV) sensitivity, inactivation of

  5. High-Resolution Mapping of Modified DNA Nucleobases Using Excision Repair Enzymes.

    Science.gov (United States)

    Ransom, Monica; Bryan, D Suzi; Hesselberth, Jay R

    2018-01-01

    Modification of DNA nucleobases has a profound effect on genome function. We developed a method that maps the positions of the modified DNA nucleobases throughout genomic DNA. This method couples in vitro nucleobase excision with massively parallel DNA sequencing to determine the location of modified DNA nucleobases with single base precision. This protocol was used to map uracil incorporation and UV photodimers in DNA, and a modification of the protocol has been used to map sparse modification events in cells. The Excision-seq protocol is broadly applicable to a variety of base modifications for which an excision enzyme is available.

  6. Defective thymine dimer excision by cell-free extracts of xeroderma pigmentosum cells.

    Science.gov (United States)

    Mortelmans, K; Friedberg, E C; Slor, H; Thomas, G; Cleaver, J E

    1976-01-01

    Crude extracts of normal human diploid fibroblasts and of human peripheral blood lymphocytes excise thymine dimers from purified ultraviolet-irradiated DNA, or from the DNA presumably present as chromatin in unfractionated cell-free preparations of cells that had been labeled with [3H]thymidine. Extracts of xeroderma pigmentosum cells from complementation groups A, C, and D also excise thymine dimers from purified DNA, but extracts of group A cells do not excise dimers from the DNA of radioactively labeled unfractionated cell-free preparations. PMID:1066689

  7. Recognition and repair of the cyclobutane thymine dimer, a major cause of skin cancers, by the human excision nuclease.

    Science.gov (United States)

    Reardon, Joyce T; Sancar, Aziz

    2003-10-15

    The cyclobutane thymine dimer is the major DNA lesion induced in human skin by sunlight and is a primary cause of skin cancer, the most prevalent form of cancer in the Northern Hemisphere. In humans, the only known cellular repair mechanism for eliminating the dimer from DNA is nucleotide excision repair. Yet the mechanism by which the dimer is recognized and removed by this repair system is not known. Here we demonstrate that the six-factor human excision nuclease recognizes and removes the dimer at a rate consistent with the in vivo rate of removal of this lesion, even though none of the six factors alone is capable of efficiently discriminating the dimer from undamaged DNA. We propose a recognition mechanism by which the low-specificity recognition factors, RPA, XPA, and XPC, act in a cooperative manner to locate the lesion and, aided by the kinetic proofreading provided by TFIIH, form a high-specificity complex at the damage site that initiates removal of thymine dimers at a physiologically relevant rate and specificity.

  8. Approaches to diagnose DNA mismatch repair gene defects in cancer.

    Science.gov (United States)

    Peña-Diaz, Javier; Rasmussen, Lene Juel

    2016-02-01

    The DNA repair pathway mismatch repair (MMR) is responsible for the recognition and correction of DNA biosynthetic errors caused by inaccurate nucleotide incorporation during replication. Faulty MMR leads to failure to address the mispairs or insertion deletion loops (IDLs) left behind by the replicative polymerases and results in increased mutation load at the genome. The realization that defective MMR leads to a hypermutation phenotype and increased risk of tumorigenesis highlights the relevance of this pathway for human disease. The association of MMR defects with increased risk of cancer development was first observed in colorectal cancer patients that carried inactivating germline mutations in MMR genes and the disease was named as hereditary non-polyposis colorectal cancer (HNPCC). Currently, a growing list of cancers is found to be MMR defective and HNPCC has been renamed Lynch syndrome (LS) partly to include the associated risk of developing extra-colonic cancers. In addition, a number of non-hereditary, mostly epigenetic, alterations of MMR genes have been described in sporadic tumors. Besides conferring a strong cancer predisposition, genetic or epigenetic inactivation of MMR genes also renders cells resistant to some chemotherapeutic agents. Therefore, diagnosis of MMR deficiency has important implications for the management of the patients, the surveillance of their relatives in the case of LS and for the choice of treatment. Some of the alterations found in MMR genes have already been well defined and their pathogenicity assessed. Despite this substantial wealth of knowledge, the effects of a large number of alterations remain uncharacterized (variants of uncertain significance, VUSs). The advent of personalized genomics is likely to increase the list of VUSs found in MMR genes and anticipates the need of diagnostic tools for rapid assessment of their pathogenicity. This review describes current tools and future strategies for addressing the relevance

  9. Preferential repair of ionizing radiation-induced damage in the transcribed strand of an active human gene is defective in Cockayne syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Leadon, S.A. (Univ. of North Carolina, Chapel Hill, NC (United States)); Copper, P.K. (Lawrence Berkeley Lab., CA (United States))

    1993-11-15

    Cells from patients with Cockayne syndrome (CS), which are sensitive to killing by UV although overall damage removal appears normal, are specifically defective in repair of UV damage in actively transcribe genes. Because several CS strains display cross-sensitivity to killing by ionizing radiation, the authors examined whether ionizing radiation-induced damage in active genes is preferentially repaired by normal cells and whether the radiosensitivity of CS cells can be explained by a defect in this process. They found that ionizing radiation-induced damage was repaired more rapidly in the transcriptionally active metallothionein IIA (MTIIA) gene than in the inactive MTIIB gene or in the genome overall in normal cells as a result of faster repair on the transcribed strand of MTIIA. Cells of the radiosensitive CS strain CS1AN are completely defective in this strand-selective repair of ionizing radiation-induced damage, although their overall repair rate appears normal. CS3BE cells, which are intermediate in radiosensitivity, do exhibit more rapid repair of the transcribed strand but at a reduced rate compared to normal cells. Xeroderma pigmentosum complementation group A cells, which are hypersensitive to UV light because of a defect in the nucleotide excision repair pathway but do not show increased sensitivity to ionizing radiation, preferentially repair ionizing radiation-induced damage on the transcribed strand of MTIIA. Thus, the ability to rapidly repair ionizing radiation-induced damage in actively transcribing genes correlates with cell survival. The results extend the generality of preferential repair in active genes to include damage other than bulky lesions.

  10. Preferential repair of ionizing radiation-induced damage in the transcribed strand of an active human gene is defective in Cockayne syndrome.

    Science.gov (United States)

    Leadon, S A; Cooper, P K

    1993-11-15

    Cells from patients with Cockayne syndrome (CS), which are sensitive to killing by UV although overall damage removal appears normal, are specifically defective in repair of UV damage in actively transcribed genes. Because several CS strains display cross-sensitivity to killing by ionizing radiation, we examined whether ionizing radiation-induced damage in active genes is preferentially repaired by normal cells and whether the radiosensitivity of CS cells can be explained by a defect in this process. We found that ionizing radiation-induced damage was repaired more rapidly in the transcriptionally active metallothionein IIA (MTIIA) gene than in the inactive MTIIB gene or in the genome overall in normal cells as a result of faster repair on the transcribed strand of MTIIA. Cells of the radiosensitive CS strain CS1AN are completely defective in this strand-selective repair of ionizing radiation-induced damage, although their overall repair rate appears normal. CS3BE cells, which are intermediate in radiosensitivity, do exhibit more rapid repair of the transcribed strand but at a reduced rate compared to normal cells. Xeroderma pigmentosum complementation group A cells, which are hypersensitive to UV light because of a defect in the nucleotide excision repair pathway but do not show increased sensitivity to ionizing radiation, preferentially repair ionizing radiation-induced damage on the transcribed strand of MTIIA. Thus, the ability to rapidly repair ionizing radiation-induced damage in actively transcribing genes correlates with cell survival. Our results extend the generality of preferential repair in active genes to include damage other than bulky lesions.

  11. The C-terminal Region and SUMOylation of Cockayne Syndrome Group B Protein Play Critical Roles in Transcription-coupled Nucleotide Excision Repair.

    Science.gov (United States)

    Sin, Yooksil; Tanaka, Kiyoji; Saijo, Masafumi

    2016-01-15

    Cockayne syndrome (CS) is a recessive disorder that results in deficiencies in transcription-coupled nucleotide excision repair (TC-NER), a subpathway of nucleotide excision repair, and cells from CS patients exhibit hypersensitivity to UV light. CS group B protein (CSB), which is the gene product of one of the genes responsible for CS, belongs to the SWI2/SNF2 DNA-dependent ATPase family and has an ATPase domain and an ubiquitin-binding domain (UBD) in the central region and the C-terminal region, respectively. The C-terminal region containing the UBD is essential for the functions of CSB. In this study, we generated several CSB deletion mutants and analyzed the functions of the C-terminal region of CSB in TC-NER. Not only the UBD but also the C-terminal 30-amino acid residues were required for UV light resistance and TC-NER. This region was needed for the interaction of CSB with RNA polymerase II, the translocation of CS group A protein to the nuclear matrix, and the association of CSB with chromatin after UV irradiation. CSB was modified by small ubiquitin-like modifier 2/3 in a UV light-dependent manner. This modification was abolished in a CSB mutant lacking the C-terminal 30 amino acid residues. However, the substitution of lysine residues in this region with arginine did not affect SUMOylation or TC-NER. By contrast, substitution of a lysine residue in the N-terminal region with arginine decreased SUMOylation and resulted in cells with defects in TC-NER. These results indicate that both the most C-terminal region and SUMOylation are important for the functions of CSB in TC-NER. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. The C-terminal Region and SUMOylation of Cockayne Syndrome Group B Protein Play Critical Roles in Transcription-coupled Nucleotide Excision Repair*

    Science.gov (United States)

    Sin, Yooksil; Tanaka, Kiyoji; Saijo, Masafumi

    2016-01-01

    Cockayne syndrome (CS) is a recessive disorder that results in deficiencies in transcription-coupled nucleotide excision repair (TC-NER), a subpathway of nucleotide excision repair, and cells from CS patients exhibit hypersensitivity to UV light. CS group B protein (CSB), which is the gene product of one of the genes responsible for CS, belongs to the SWI2/SNF2 DNA-dependent ATPase family and has an ATPase domain and an ubiquitin-binding domain (UBD) in the central region and the C-terminal region, respectively. The C-terminal region containing the UBD is essential for the functions of CSB. In this study, we generated several CSB deletion mutants and analyzed the functions of the C-terminal region of CSB in TC-NER. Not only the UBD but also the C-terminal 30-amino acid residues were required for UV light resistance and TC-NER. This region was needed for the interaction of CSB with RNA polymerase II, the translocation of CS group A protein to the nuclear matrix, and the association of CSB with chromatin after UV irradiation. CSB was modified by small ubiquitin-like modifier 2/3 in a UV light-dependent manner. This modification was abolished in a CSB mutant lacking the C-terminal 30 amino acid residues. However, the substitution of lysine residues in this region with arginine did not affect SUMOylation or TC-NER. By contrast, substitution of a lysine residue in the N-terminal region with arginine decreased SUMOylation and resulted in cells with defects in TC-NER. These results indicate that both the most C-terminal region and SUMOylation are important for the functions of CSB in TC-NER. PMID:26620705

  13. Stabilization of Ultraviolet (UV)-stimulated Scaffold Protein A by Interaction with Ubiquitin-specific Peptidase 7 Is Essential for Transcription-coupled Nucleotide Excision Repair.

    Science.gov (United States)

    Higa, Mitsuru; Zhang, Xue; Tanaka, Kiyoji; Saijo, Masafumi

    2016-06-24

    UV-sensitive syndrome is an autosomal recessive disorder characterized by hypersensitivity to UV light and deficiency in transcription-coupled nucleotide excision repair (TC-NER), a subpathway of nucleotide excision repair that rapidly removes transcription-blocking DNA damage. UV-sensitive syndrome consists of three genetic complementation groups caused by mutations in the CSA, CSB, and UVSSA genes. UV-stimulated scaffold protein A (UVSSA), the product of UVSSA, which is required for stabilization of Cockayne syndrome group B (CSB) protein and reappearance of the hypophosphorylated form of RNA polymerase II after UV irradiation, forms a complex with ubiquitin-specific peptidase 7 (USP7). In this study, we demonstrated that the deubiquitination activity of USP7 is suppressed by its interaction with UVSSA. The interaction required the tumor necrosis factor receptor-associated factor domain of USP7 and the central region of UVSSA and was disrupted by an amino acid substitution in the tumor necrosis factor receptor-associated factor-binding motif of UVSSA. Cells expressing mutant UVSSA were highly sensitive to UV irradiation and defective in recovery of RNA synthesis after UV irradiation. These results indicate that the interaction between UVSSA and USP7 is important for TC-NER. Furthermore, the mutant UVSSA was rapidly degraded by the proteasome, and CSB was also degraded after UV irradiation as observed in UVSSA-deficient cells. Thus, stabilization of UVSSA by interaction with USP7 is essential for TC-NER. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Molecular and cellular analysis of the DNA repair defect in a patient in xeroderma pigmentosum complementation group D who has the clinical features of xeroderma pigmentosum and Cockayne syndrome.

    NARCIS (Netherlands)

    B.C. Broughton; A.F. Thompson; S.A. Harcourt; W. Vermeulen (Wim); J.H.J. Hoeijmakers (Jan); E. Botta (Elena); M. Stefanini (Miria); M.D. King; C.A. Weber (Christine); J. Cole; C.F. Arlett (Colin); A.R. Lehmann (Alan)

    1995-01-01

    textabstractXeroderma pigmentosum (XP) and Cockayne syndrome (CS) are quite distinct genetic disorders that are associated with defects in excision repair of UV-induced DNA damage. A few patients have been described previously with the clinical features of both disorders. In this paper we describe

  15. Cockayne syndrome: varied requirement of transcription-coupled nucleotide excision repair for the removal of three structurally different adducts from transcribed DNA.

    Directory of Open Access Journals (Sweden)

    Nataliya Kitsera

    Full Text Available Hereditary defects in the transcription-coupled nucleotide excision repair (TC-NER pathway of damaged DNA cause severe neurodegenerative disease Cockayne syndrome (CS, however the origin and chemical nature of the underlying DNA damage had remained unknown. To find out, to which degree the structural properties of DNA lesions determine the extent of transcription arrest in human CS cells, we performed quantitative host cell reactivation analyses of expression vectors containing various synthetic adducts. We found that a single 3-(deoxyguanosin-N2-yl-2-acetylaminofluorene adduct (dG(N2-AAF constitutes an unsurmountable obstacle to transcription in both CS-A and CS-B cells and is removed exclusively by the CSA- and CSB-dependent pathway. In contrast, contribution of the CS proteins to the removal of two other transcription-blocking DNA lesions - N-(deoxyguanosin-8-yl-2-acetylaminofluorene (dG(C8-AAF and cyclobutane thymine-thymine (TT dimer - is only minor (TT dimer or none (dG(C8-AAF. The unique properties of dG(N2-AAF identify this adduct as a prototype for a new class of DNA lesions that escape the alternative global genome repair and could be critical for the CS pathogenesis.

  16. Mitotic regulator Nlp interacts with XPA/ERCC1 complexes and regulates nucleotide excision repair (NER) in response to UV radiation.

    Science.gov (United States)

    Ma, Xiao-Juan; Shang, Li; Zhang, Wei-Min; Wang, Ming-Rong; Zhan, Qi-Min

    2016-04-10

    Cellular response to DNA damage, including ionizing radiation (IR) and UV radiation, is critical for the maintenance of genomic fidelity. Defects of DNA repair often result in genomic instability and malignant cell transformation. Centrosomal protein Nlp (ninein-like protein) has been characterized as an important cell cycle regulator that is required for proper mitotic progression. In this study, we demonstrate that Nlp is able to improve nucleotide excision repair (NER) activity and protects cells against UV radiation. Upon exposure of cells to UVC, Nlp is translocated into the nucleus. The C-terminus (1030-1382) of Nlp is necessary and sufficient for its nuclear import. Upon UVC radiation, Nlp interacts with XPA and ERCC1, and enhances their association. Interestingly, down-regulated expression of Nlp is found to be associated with human skin cancers, indicating that dysregulated Nlp might be related to the development of human skin cancers. Taken together, this study identifies mitotic protein Nlp as a new and important member of NER pathway and thus provides novel insights into understanding of regulatory machinery involved in NER. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Mitochondrial base excision repair in mouse synaptosomes during normal aging and in a model of Alzheimer's disease

    DEFF Research Database (Denmark)

    Diaz, Ricardo Gredilla; Weissman, Lior; Yang, Jenq-Lin

    2010-01-01

    suggest that the age-related reduction in BER capacity in the synaptosomal fraction might contribute to mitochondrial and synaptic dysfunction during aging. The development of AD-like pathology in the 3xTgAD mouse model was, however, not associated with deficiencies of the BER mechanisms......Brain aging is associated with synaptic decline and synaptic function is highly dependent on mitochondria. Increased levels of oxidative DNA base damage and accumulation of mitochondrial DNA (mtDNA) mutations or deletions lead to mitochondrial dysfunction, playing an important role in the aging...... process and the pathogenesis of several neurodegenerative diseases. Here we have investigated the repair of oxidative base damage, in synaptosomes of mouse brain during normal aging and in an AD model. During normal aging, a reduction in the base excision repair (BER) capacity was observed...

  18. Repair of tegmen defect using cranial particulate bone graft.

    Science.gov (United States)

    Greene, Arin K; Poe, Dennis S

    2015-01-01

    Bone paté is used to repair cranial bone defects. This material contains bone-dust collected during the high-speed burring of the cranium. Clinical and experimental studies of bone dust, however, have shown that it does not have biological activity and is resorbed. We describe the use of bone paté using particulate bone graft. Particulate graft is harvested with a hand-driven brace and 16mm bit; it is not subjected to thermal injury and its large size resists resorption. Bone paté containing particulate graft is much more likely than bone dust to contain viable osteoblasts capable of producing new bone. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. [EFFECTIVENESS OF REPAIRING OR RECONSTRUCTING DEFECTS OF FOREFOOT].

    Science.gov (United States)

    Wang, Zhihao; Ding, Yingjie; Yu, Zhiping; Wang, Xiaoke; Xing, Guofei; Cong, Haibo

    2016-02-01

    Between February 2006 and February 2013, 57 patients with defects of the forefoot were treated. There were 41 males and 16 females with an average age of 38.9 years (range, 19-68 years). The disease causes included motor vehicles crush injury in 28 cases, crashing injury in 17 cases, and machine extrusion injury in 12 cases. The left side was involved in 25 cases and the right side in 32 cases, with a mean disease duration of 4.7 hours (range, 0.5-75.0 hours). Defect located at the 1st metatarsus in 9 cases, at the 5th metatarsus in 8 cases, at the 1st and the 2nd metatarsus in 16 cases, at the 4th and 5th metatarsus in 11 cases, at multiple metatarsus and the forefoot in 13 cases. The bone defect ranged from 2.5 cm x 1.9 cm x 1.4 cm to 13.3 cm x 11.2 cm x 2.7 cm. The soft tissue defect ranged from 12.4 cm x 6.3 cm to 27.2 cm x 18.7 cm. The iliac bone or vascularized iliac bone or vascularized fibula bone was used to rebuild the arch of the foot, and free flap was used to repair defects of the forefoot. The donor site was sutured directly or covered with skin graft. Venous crisis and partial necrosis occurred in 3 and 2 flaps respectively, which healed after symptomatic treatment. The other flaps and grafted skins survived, and wounds healed primarily. Fifty-one cases were followed up 1.5-2.5 years (mean, 2.1 years). The appearance was excellent and the feeling of the flap recovered at different levels. The two-point discrimination was 8.4-19.8 mm (mean, 13.7 mm) at 1.5 years after operation. According to upper extremity functional evaluation standard by hand surgery branch of Chinese Medical Association, sensation recovered to 52 in 6 cases, to 53 in 18 cases, and to 54 in 27 cases. The patients began to walk with weight loading at 2-6 months after operation (mean, 3.9 months). The bone healing time was 3-6 months (mean, 4.2 months). Based on American Orthopaedic Foot and Ankle Society (AOFAS) standards, the results were excellent in 19 cases, good in 24 cases

  20. Hydrogels for the Repair of Articular Cartilage Defects

    Science.gov (United States)

    Maher, Suzanne A.; Lowman, Anthony M.

    2011-01-01

    The repair of articular cartilage defects remains a significant challenge in orthopedic medicine. Hydrogels, three-dimensional polymer networks swollen in water, offer a unique opportunity to generate a functional cartilage substitute. Hydrogels can exhibit similar mechanical, swelling, and lubricating behavior to articular cartilage, and promote the chondrogenic phenotype by encapsulated cells. Hydrogels have been prepared from naturally derived and synthetic polymers, as cell-free implants and as tissue engineering scaffolds, and with controlled degradation profiles and release of stimulatory growth factors. Using hydrogels, cartilage tissue has been engineered in vitro that has similar mechanical properties to native cartilage. This review summarizes the advancements that have been made in determining the potential of hydrogels to replace damaged cartilage or support new tissue formation as a function of specific design parameters, such as the type of polymer, degradation profile, mechanical properties and loading regimen, source of cells, cell-seeding density, controlled release of growth factors, and strategies to cause integration with surrounding tissue. Some key challenges for clinical translation remain, including limited information on the mechanical properties of hydrogel implants or engineered tissue that are necessary to restore joint function, and the lack of emphasis on the ability of an implant to integrate in a stable way with the surrounding tissue. Future studies should address the factors that affect these issues, while using clinically relevant cell sources and rigorous models of repair. PMID:21510824

  1. Repair of Head and Face Defects with the Use of Pericranial Flap

    Directory of Open Access Journals (Sweden)

    Mohammad Naeimi

    2011-01-01

    The use of a pericranial flap is a simple, quick, cost-effective and safe method for repair of head and face defects. Although, a longer follow up time is required, but this uncomplicated method has been considered as an ideal method to repair sinonasal, ear and scalp defects.

  2. The recombination protein RAD52 cooperates with the excision repair protein OGG1 for the repair of oxidative lesions in mammalian cells

    DEFF Research Database (Denmark)

    de Souza-Pinto, Nadja C; Maynard, Scott; Hashiguchi, Kazunari

    2009-01-01

    Oxidized bases are common types of DNA modifications. Their accumulation in the genome is linked to aging and degenerative diseases. These modifications are commonly repaired by the base excision repair (BER) pathway. Oxoguanine DNA glycosylase (OGG1) initiates BER of oxidized purine bases. A small...... activities and RAD52 stimulates OGG1 incision activity, likely increasing its turnover rate. RAD52 colocalizes with OGG1 after oxidative stress to cultured cells, but not after the direct induction of double-strand breaks by ionizing radiation. Human cells depleted of RAD52 via small interfering RNA...... knockdown, and mouse cells lacking the protein via gene knockout showed increased sensitivity to oxidative stress. Moreover, cells depleted of RAD52 show higher accumulation of oxidized bases in their genome than cells with normal levels of RAD52. Our results indicate that RAD52 cooperates with OGG1...

  3. Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair.

    Science.gov (United States)

    Akbari, Mansour; Keijzers, Guido; Maynard, Scott; Scheibye-Knudsen, Morten; Desler, Claus; Hickson, Ian D; Bohr, Vilhelm A

    2014-04-01

    Base excision repair (BER) is the most prominent DNA repair pathway in human mitochondria. BER also results in a temporary generation of AP-sites, single-strand breaks and nucleotide gaps. Thus, incomplete BER can result in the generation of DNA repair intermediates that can disrupt mitochondrial DNA replication and transcription and generate mutations. We carried out BER analysis in highly purified mitochondrial extracts from human cell lines U2OS and HeLa, and mouse brain using a circular DNA substrate containing a lesion at a specific position. We found that DNA ligation is significantly slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I by rotenone. Our results suggest that the amount of DNA ligase III in mitochondria may be critical for cell survival following prolonged oxidative stress, and demonstrate a functional link between mitochondrial DNA damage and repair, cell survival upon oxidative stress, and removal of dysfunctional mitochondria by autophagy. Copyright © 2014. Published by Elsevier B.V.

  4. Histone H3 Lys79 methylation is required for efficient nucleotide excision repair in a silenced locus of Saccharomyces cerevisiae

    Science.gov (United States)

    Chaudhuri, Shubho; Wyrick, John J.; Smerdon, Michael J.

    2009-01-01

    Methylation of specific histone lysine residues regulates gene expression and heterochromatin function, but little is known about its role in DNA repair. To examine how changes in conserved methylated residues of histone H3 affect nucleotide excision repair (NER), viable H3K4R and H3K79R mutants were generated in Saccharomyces cerevisiae. These mutants show decreased UV survival and impaired NER at the transcriptionally silent HML locus, while maintaining normal NER in the constitutively expressed RPB2 gene and transcriptionally repressed, nucleosome loaded GAL10 gene. Moreover, the HML chromatin in these mutants has reduced accessibility to Micrococcal nuclease (MNase). Importantly, chromatin immunoprecipitation analysis demonstrates there is enhanced recruitment of the Sir complex at the HML locus of these mutants, and deletion of the SIR2 or SIR3 genes restores the MNase accessibility and DNA repair efficiency at this locus. Furthermore, following UV irradiation expression of NER genes in these mutants remains at wild type levels, with the exception of RAD16 which decreases by more than 2-fold. These results indicate that impaired NER occurs in the silenced chromatin of H3K79R and H3K4,79R mutants as a result of increased binding of Sir complexes, which may reduce DNA lesion accessibility to repair enzymes. PMID:19155276

  5. Nucleotide sequence, DNA damage location and protein stoichiometry influence base excision repair outcome at CAG/CTG repeats

    Science.gov (United States)

    Goula, Agathi-Vasiliki; Pearson, Christopher E.; Della Maria, Julie; Trottier, Yvon; Tomkinson, Alan E.; Wilson, David M.; Merienne, Karine

    2012-01-01

    Expansion of CAG/CTG repeats is the underlying cause of >fourteen genetic disorders, including Huntington’s disease (HD) and myotonic dystrophy. The mutational process is ongoing, with increases in repeat size enhancing the toxicity of the expansion in specific tissues. In many repeat diseases the repeats exhibit high instability in the striatum, whereas instability is minimal in the cerebellum. We provide molecular insights as to how base excision repair (BER) protein stoichiometry may contribute to the tissue-selective instability of CAG/CTG repeats by using specific repair assays. Oligonucleotide substrates with an abasic site were mixed with either reconstituted BER protein stoichiometries mimicking the levels present in HD mouse striatum or cerebellum, or with protein extracts prepared from HD mouse striatum or cerebellum. In both cases, repair efficiency at CAG/CTG repeats and at control DNA sequences was markedly reduced under the striatal conditions, likely due to the lower level of APE1, FEN1 and LIG1. Damage located towards the 5’ end of the repeat tract was poorly repaired accumulating incompletely processed intermediates as compared to an AP lesion in the centre or at the 3’ end of the repeats or within a control sequences. Moreover, repair of lesions at the 5’ end of CAG or CTG repeats involved multinucleotide synthesis, particularly under the cerebellar stoichiometry, suggesting that long-patch BER processes lesions at sequences susceptible to hairpin formation. Our results show that BER stoichiometry, nucleotide sequence and DNA damage position modulate repair outcome, and suggest that a suboptimal LP-BER activity promotes CAG/CTG repeat instability. PMID:22497302

  6. The nucleotide sequence, DNA damage location, and protein stoichiometry influence the base excision repair outcome at CAG/CTG repeats.

    Science.gov (United States)

    Goula, Agathi-Vasiliki; Pearson, Christopher E; Della Maria, Julie; Trottier, Yvon; Tomkinson, Alan E; Wilson, David M; Merienne, Karine

    2012-05-08

    Expansion of CAG/CTG repeats is the underlying cause of >14 genetic disorders, including Huntington's disease (HD) and myotonic dystrophy. The mutational process is ongoing, with increases in repeat size enhancing the toxicity of the expansion in specific tissues. In many repeat diseases, the repeats exhibit high instability in the striatum, whereas instability is minimal in the cerebellum. We provide molecular insights into how base excision repair (BER) protein stoichiometry may contribute to the tissue-selective instability of CAG/CTG repeats by using specific repair assays. Oligonucleotide substrates with an abasic site were mixed with either reconstituted BER protein stoichiometries mimicking the levels present in HD mouse striatum or cerebellum, or with protein extracts prepared from HD mouse striatum or cerebellum. In both cases, the repair efficiency at CAG/CTG repeats and at control DNA sequences was markedly reduced under the striatal conditions, likely because of the lower level of APE1, FEN1, and LIG1. Damage located toward the 5' end of the repeat tract was poorly repaired, with the accumulation of incompletely processed intermediates as compared to an AP lesion in the center or at the 3' end of the repeats or within control sequences. Moreover, repair of lesions at the 5' end of CAG or CTG repeats involved multinucleotide synthesis, particularly at the cerebellar stoichiometry, suggesting that long-patch BER processes lesions at sequences susceptible to hairpin formation. Our results show that the BER stoichiometry, nucleotide sequence, and DNA damage position modulate repair outcome and suggest that a suboptimal long-patch BER activity promotes CAG/CTG repeat instability.

  7. Modulation of base excision repair of 8-oxoguanine by the nucleotide sequence.

    Science.gov (United States)

    Allgayer, Julia; Kitsera, Nataliya; von der Lippen, Carina; Epe, Bernd; Khobta, Andriy

    2013-10-01

    8-Oxoguanine (8-oxoG) is a major product of oxidative DNA damage, which induces replication errors and interferes with transcription. By varying the position of single 8-oxoG in a functional gene and manipulating the nucleotide sequence surrounding the lesion, we found that the degree of transcriptional inhibition is independent of the distance from the transcription start or the localization within the transcribed or the non-transcribed DNA strand. However, it is strongly dependent on the sequence context and also proportional to cellular expression of 8-oxoguanine DNA glycosylase (OGG1)-demonstrating that transcriptional arrest does not take place at unrepaired 8-oxoG and proving a causal connection between 8-oxoG excision and the inhibition of transcription. We identified the 5'-CAGGGC[8-oxoG]GACTG-3' motif as having only minimal transcription-inhibitory potential in cells, based on which we predicted that 8-oxoG excision is particularly inefficient in this sequence context. This anticipation was fully confirmed by direct biochemical assays. Furthermore, in DNA containing a bistranded Cp[8-oxoG]/Cp[8-oxoG] clustered lesion, the excision rates differed between the two strands at least by a factor of 9, clearly demonstrating that the excision preference is defined by the DNA strand asymmetry rather than the overall geometry of the double helix or local duplex stability.

  8. Xeroderma pigmentosum-Cockayne syndrome complex in two patients: absence of skin tumors despite severe deficiency of DNA excision repair.

    Science.gov (United States)

    Scott, R J; Itin, P; Kleijer, W J; Kolb, K; Arlett, C; Muller, H

    1993-11-01

    Two brothers had a complex combination of two DNA repair disorders: Cockayne syndrome and xeroderma pigmentosum. This rare combination has previously been observed in only two other patients. The clinical signs shared by these two brothers and the two other previously described patients include severe sun sensitivity, freckling, diminished stature, hearing and movement impairment, and neurologic degeneration. Although defective UV-induced unscheduled DNA synthesis has been demonstrated (5% of normal), no skin cancers have appeared in these 38- and 41-year-old brothers, whereas skin cancers developed at a relatively early age in the two previously described patients who also had defective UV-induced unscheduled DNA synthesis.

  9. Defective transcription-coupled repair in Cockayne syndrome B mice is associated with skin cancer predisposition.

    Science.gov (United States)

    van der Horst, G T; van Steeg, H; Berg, R J; van Gool, A J; de Wit, J; Weeda, G; Morreau, H; Beems, R B; van Kreijl, C F; de Gruijl, F R; Bootsma, D; Hoeijmakers, J H

    1997-05-02

    A mouse model for the nucleotide excision repair disorder Cockayne syndrome (CS) was generated by mimicking a truncation in the CSB(ERCC6) gene of a CS-B patient. CSB-deficient mice exhibit all of the CS repair characteristics: ultraviolet (UV) sensitivity, inactivation of transcription-coupled repair, unaffected global genome repair, and inability to resume RNA synthesis after UV exposure. Other CS features thought to involve the functioning of basal transcription/repair factor TFIIH, such as growth failure and neurologic dysfunction, are present in mild form. In contrast to the human syndrome, CSB-deficient mice show increased susceptibility to skin cancer. Our results demonstrate that transcription-coupled repair of UV-induced cyclobutane pyrimidine dimers contributes to the prevention of carcinogenesis in mice. Further, they suggest that the lack of cancer predisposition in CS patients is attributable to a global genome repair process that in humans is more effective than in rodents.

  10. Cytosine deamination and base excision repair cause R-loop-induced CAG repeat fragility and instability in Saccharomyces cerevisiae.

    Science.gov (United States)

    Su, Xiaofeng A; Freudenreich, Catherine H

    2017-10-03

    CAG/CTG repeats are structure-forming repetitive DNA sequences, and expansion beyond a threshold of ∼35 CAG repeats is the cause of several human diseases. Expanded CAG repeats are prone to breakage, and repair of the breaks can cause repeat contractions and expansions. In this study, we found that cotranscriptional R-loops formed at a CAG-70 repeat inserted into a yeast chromosome. R-loops were further elevated upon deletion of yeast RNaseH genes and caused repeat fragility. A significant increase in CAG repeat contractions was also observed, consistent with previous human cell studies. Deletion of yeast cytosine deaminase Fcy1 significantly decreased the rate of CAG repeat fragility and contractions in the rnh1Δrnh201Δ background, indicating that Fcy1-mediated deamination is one cause of breakage and contractions in the presence of R-loops. Furthermore, base excision repair (BER) is responsible for causing CAG repeat contractions downstream of Fcy1, but not fragility. The Rad1/XPF and Rad2/XPG nucleases were also important in protecting against contractions, but through BER rather than nucleotide excision repair. Surprisingly, the MutLγ (Mlh1/Mlh3) endonuclease caused R-loop-dependent CAG fragility, defining an alternative function for this complex. These findings provide evidence that breakage at expanded CAG repeats occurs due to R-loop formation and reveal two mechanisms for CAG repeat instability: one mediated by cytosine deamination of DNA engaged in R-loops and the other by MutLγ cleavage. Since disease-causing CAG repeats occur in transcribed regions, our results suggest that R-loop-mediated fragility is a mechanism that could cause DNA damage and repeat-length changes in human cells.

  11. Laxity of the elbow after experimental excision of the radial head and division of the medial collateral ligament. Efficacy of ligament repair and radial head prosthetic replacement

    DEFF Research Database (Denmark)

    Jensen, Steen Lund; Deutch, Søren R; Olsen, Bo Sanderhoff

    2003-01-01

    We studied the stabilising effect of prosthetic replacement of the radial head and repair of the medial collateral ligament (MCL) after excision of the radial head and section of the MCL in five cadaver elbows. Division of the MCL increased valgus angulation (mean 3.9 +/- 1.5 degrees) and internal...... that the radial head is a constraint secondary to the MCL for both valgus displacement and internal rotation. Isolated repair of the ligament is superior to isolated prosthetic replacement and may be sufficient to restore valgus and internal rotatory stability after excision of the radial head in MCL...

  12. Local flap for reconstruction of nasal defect following excision of basal cell carcinoma of nose

    Directory of Open Access Journals (Sweden)

    Hasib Rahman

    2016-12-01

    Full Text Available Reconstruction of soft tissue at the nose following excision of basal cell carcinoma is always challenging, because of both functional and aesthetic importance of nose. The local flap is always preferable to skin graft as this produces “like with like” replacement, pliable cover and vascularized tissue over the skeletal framework. In this paper, we discussed six cases of nasal reconstruction with bilobed flap, forehead flap, and nasolabial flap. All flaps survived and the patients had satisfactory outcome.

  13. An inverse switch in DNA base excision and strand break repair contributes to melphalan resistance in multiple myeloma cells.

    Directory of Open Access Journals (Sweden)

    Mirta M L Sousa

    Full Text Available Alterations in checkpoint and DNA repair pathways may provide adaptive mechanisms contributing to acquired drug resistance. Here, we investigated the levels of proteins mediating DNA damage signaling and -repair in RPMI8226 multiple myeloma cells and its Melphalan-resistant derivative 8226-LR5. We observed markedly reduced steady-state levels of DNA glycosylases UNG2, NEIL1 and MPG in the resistant cells and cross-resistance to agents inducing their respective DNA base lesions. Conversely, repair of alkali-labile sites was apparently enhanced in the resistant cells, as substantiated by alkaline comet assay, autoribosylation of PARP-1, and increased sensitivity to PARP-1 inhibition by 4-AN or KU58684. Reduced base-excision and enhanced single-strand break repair would both contribute to the observed reduction in genomic alkali-labile sites, which could jeopardize productive processing of the more cytotoxic Melphalan-induced interstrand DNA crosslinks (ICLs. Furthermore, we found a marked upregulation of proteins in the non-homologous end-joining (NHEJ pathway of double-strand break (DSB repair, likely contributing to the observed increase in DSB repair kinetics in the resistant cells. Finally, we observed apparent upregulation of ATR-signaling and downregulation of ATM-signaling in the resistant cells. This was accompanied by markedly increased sensitivity towards Melphalan in the presence of ATR-, DNA-PK, or CHK1/2 inhibitors whereas no sensitizing effect was observed subsequent to ATM inhibition, suggesting that replication blocking lesions are primary triggers of the DNA damage response in the Melphalan resistant cells. In conclusion, Melphalan resistance is apparently contributed by modulation of the DNA damage response at multiple levels, including downregulation of specific repair pathways to avoid repair intermediates that could impair efficient processing of cytotoxic ICLs and ICL-induced DSBs. This study has revealed several novel

  14. A UV-Induced Genetic Network Links the RSC Complex to Nucleotide Excision Repair and Shows Dose-Dependent Rewiring

    Directory of Open Access Journals (Sweden)

    Rohith Srivas

    2013-12-01

    Full Text Available Efficient repair of UV-induced DNA damage requires the precise coordination of nucleotide excision repair (NER with numerous other biological processes. To map this crosstalk, we generated a differential genetic interaction map centered on quantitative growth measurements of >45,000 double mutants before and after different doses of UV radiation. Integration of genetic data with physical interaction networks identified a global map of 89 UV-induced functional interactions among 62 protein complexes, including a number of links between the RSC complex and several NER factors. We show that RSC is recruited to both silenced and transcribed loci following UV damage where it facilitates efficient repair by promoting nucleosome remodeling. Finally, a comparison of the response to high versus low levels of UV shows that the degree of genetic rewiring correlates with dose of UV and reveals a network of dose-specific interactions. This study makes available a large resource of UV-induced interactions, and it illustrates a methodology for identifying dose-dependent interactions based on quantitative shifts in genetic networks.

  15. Quantitation of intracellular NAD(P)H can monitor an imbalance of DNA single strand break repair in base excision repair deficient cells in real time

    Science.gov (United States)

    Nakamura, Jun; Asakura, Shoji; Hester, Susan D.; de Murcia, Gilbert; Caldecott, Keith W.; Swenberg, James A.

    2003-01-01

    DNA single strand breaks (SSBs) are one of the most frequent DNA lesions in genomic DNA generated either by oxidative stress or during the base excision repair pathways. Here we established a new real-time assay to assess an imbalance of DNA SSB repair by indirectly measuring PARP-1 activation through the depletion of intracellular NAD(P)H. A water-soluble tetrazolium salt is used to monitor the amount of NAD(P)H in living cells through its reduction to a yellow colored water-soluble formazan dye. While this assay is not a direct method, it does not require DNA extraction or alkaline treatment, both of which could potentially cause an artifactual induction of SSBs. In addition, it takes only 4 h and requires less than a half million cells to perform this measurement. Using this assay, we demonstrated that the dose- and time-dependent depletion of NAD(P)H in XRCC1-deficient CHO cells exposed to methyl methanesulfonate. This decrease was almost completely blocked by a PARP inhibitor. Furthermore, methyl methanesulfonate reduced NAD(P)H in PARP-1+/+cells, whereas PARP-1–/– cells were more resistant to the decrease in NAD(P)H. These results indicate that the analysis of intracellular NAD(P)H level using water-soluble tetrazolium salt can assess an imbalance of SSB repair in living cells in real time. PMID:12930978

  16. Laparoscopic Partial Cystectomy With Excision of Mesh Migration Into the Bladder Following Repair of Inguinal Hernia

    Directory of Open Access Journals (Sweden)

    Satoshi Funada

    2016-09-01

    Full Text Available Migration of hernia mesh into the bladder is a rare complication of inguinal hernioplasty. We present the case of an 85-year-old man who complained of hematuria and fever some 20 years after right hernioplasty. Cystoscopy and computed tomography revealed mesh migration into the right anterior wall of the bladder. Laparoscopic partial cystectomy with excision of the migrated mesh was performed successfully. To our knowledge, this is the first case of mesh migration into the bladder treated by laparoscopic partial cystectomy.

  17. 1-beta-D-Arabinofuranosylcytosine is Cytotoxic in Quiescent Normal Lymphocytes Undergoing DNA Excision Repair

    OpenAIRE

    Yamauchi, Takahiro; Kawai, Yasukazu; Ueda, Takanori

    2002-01-01

    We have sought to clarify the potential activity of S-phase specific antileukemic agent 1--D-arabinofuranosylcytosine (ara-C), an inhibitor of DNA synthesis, in quiescent cells that are substantially non-sensitive to nucleoside analogues. It was hypothesized that the combination of ara-C with DNA damaging agents that initiate DNA repair will expand ara-C cytotoxicity to non-cycling cells. The repair kinetics, which included incision of damaged DNA, gap filling by DNA synthesis and rejoinin...

  18. The Challenges of Validating in Precision Medicine: The Case of Excision Repair Cross-Complement Group 1 Diagnostic Testing.

    Science.gov (United States)

    Barsanti-Innes, Brianna; Hey, Spencer Phillips; Kimmelman, Jonathan

    2017-01-01

    Personalized medicine relies upon the successful identification and translation of predictive biomarkers. Unfortunately, biomarker development has often fallen short of expectations. To better understand the obstacles to successful biomarker development, we systematically mapped research activities for a biomarker that has been in development for at least 12 years: excision repair cross-complement group 1 protein (ERCC1) as a biomarker for predicting clinical benefit with platinum-based chemotherapy in non-small cell lung cancer. We found that although research activities explored a wide range of approaches to ERCC1 testing, there was little replication or validation of techniques, and design and reporting of results were generally poor. Our analysis points to problems with coordinating and standardizing research in biomarker development. Clinically meaningful progress in personalized medicine will require concerted efforts to address these problems. In the interim, health care providers should be aware of the complexity involved in biomarker development, cautious about their near-term clinical value, and conscious of applying only validated diagnostics in the clinic. 2017;22:89-96 IMPLICATIONS FOR PRACTICE: : Many hospitals, policy makers, and scientists have made ambitious claims about the promise of personalizing cancer care. When one uses a case example of excision repair cross-complement group 1 protein-a biomarker that has a strong biological rationale and that has been researched for 12 years-the current research environment seems poorly suited for efficient development of biomarker tests. The findings provide grounds for tempering expectations about personalized cancer care-at least in the near term-and shed light on the current gap between the promise and practice of personalized medicine. © AlphaMed Press 2016.

  19. Silymarin protects epidermal keratinocytes from ultraviolet radiation-induced apoptosis and DNA damage by nucleotide excision repair mechanism.

    Directory of Open Access Journals (Sweden)

    Santosh K Katiyar

    Full Text Available Solar ultraviolet (UV radiation is a well recognized epidemiologic risk factor for melanoma and non-melanoma skin cancers. This observation has been linked to the accumulation of UVB radiation-induced DNA lesions in cells, and that finally lead to the development of skin cancers. Earlier, we have shown that topical treatment of skin with silymarin, a plant flavanoid from milk thistle (Silybum marianum, inhibits photocarcinogenesis in mice; however it is less understood whether chemopreventive effect of silymarin is mediated through the repair of DNA lesions in skin cells and that protect the cells from apoptosis. Here, we show that treatment of normal human epidermal keratinocytes (NHEK with silymarin blocks UVB-induced apoptosis of NHEK in vitro. Silymarin reduces the amount of UVB radiation-induced DNA damage as demonstrated by reduced amounts of cyclobutane pyrimidine dimers (CPDs and as measured by comet assay, and that ultimately may lead to reduced apoptosis of NHEK. The reduction of UV radiation-induced DNA damage by silymarin appears to be related with induction of nucleotide excision repair (NER genes, because UV radiation-induced apoptosis was not blocked by silymarin in NER-deficient human fibroblasts. Cytostaining and dot-blot analysis revealed that silymarin repaired UV-induced CPDs in NER-proficient fibroblasts from a healthy individual but did not repair UV-induced CPD-positive cells in NER-deficient fibroblasts from patients suffering from xeroderma pigmentosum complementation-A disease. Similarly, immunohistochemical analysis revealed that silymarin did not reduce the number of UVB-induced sunburn/apoptotic cells in the skin of NER-deficient mice, but reduced the number of sunburn cells in their wild-type counterparts. Together, these results suggest that silymarin exert the capacity to reduce UV radiation-induced DNA damage and, thus, prevent the harmful effects of UV radiation on the genomic stability of epidermal cells.

  20. Is bone transplantation the gold standard for repair of alveolar bone defects?

    Directory of Open Access Journals (Sweden)

    Cassio Eduardo Raposo-Amaral

    2014-01-01

    Full Text Available New strategies to fulfill craniofacial bone defects have gained attention in recent years due to the morbidity of autologous bone graft harvesting. We aimed to evaluate the in vivo efficacy of bone tissue engineering strategy using mesenchymal stem cells associated with two matrices (bovine bone mineral and α-tricalcium phosphate, compared to an autologous bone transfer. A total of 28 adult, male, non-immunosuppressed Wistar rats underwent a critical-sized osseous defect of 5 mm diameter in the alveolar region. Animals were divided into five groups. Group 1 (n = 7 defects were repaired with autogenous bone grafts; Group 2 (n = 5 defects were repaired with bovine bone mineral free of cells; Group 3 (n = 5 defects were repaired with bovine bone mineral loaded with mesenchymal stem cells; Group 4 (n = 5 defects were repaired with α-tricalcium phosphate free of cells; and Group 5 (n = 6 defects were repaired with α-tricalcium phosphate loaded with mesenchymal stem cells. Groups 2–5 were compared to Group 1, the reference group. Healing response was evaluated by histomorphometry and computerized tomography. Histomorphometrically, Group 1 showed 60.27% ± 16.13% of bone in the defect. Groups 2 and 3 showed 23.02% ± 8.6% (p = 0.01 and 38.35% ± 19.59% (p = 0.06 of bone in the defect, respectively. Groups 4 and 5 showed 51.48% ± 11.7% (p = 0.30 and 61.80% ± 2.14% (p = 0.88 of bone in the defect, respectively. Animals whose bone defects were repaired with α-tricalcium phosphate and mesenchymal stem cells presented the highest bone volume filling the defects; both were not statistically different from autogenous bone.

  1. Intrathoracic splenosis secondary to previous penetrating thoracoabdominal trauma diagnosed during delayed diaphragmatic hernia repair

    National Research Council Canada - National Science Library

    Aktekin, Ali; Gürleyik, Günay; Arman, Alper; Pekcan, Hüseyin; Sağlam, Abdullah

    2006-01-01

    .... We have intraoperatively recognized that many pieces of splenic tissue have been herniated through a diaphragmatic defect, and formed intrathoracic splenosis. We repaired the diaphragmatic hernia defect after excision of fragments of the spleen.

  2. DNA glycosylases involved in base excision repair may be associated with cancer risk in BRCA1 and BRCA2 mutation carriers

    DEFF Research Database (Denmark)

    Osorio, Ana; Milne, Roger L; Kuchenbaecker, Karoline

    2014-01-01

    Single Nucleotide Polymorphisms (SNPs) in genes involved in the DNA Base Excision Repair (BER) pathway could be associated with cancer risk in carriers of mutations in the high-penetrance susceptibility genes BRCA1 and BRCA2, given the relation of synthetic lethality that exists between one of th...

  3. The role of Schizosaccharomyces pombe DNA repair enzymes Apn1p and Uve1p in the base excision repair of apurinic/apyrimidinic sites.

    Science.gov (United States)

    Tanihigashi, Haruna; Yamada, Ayako; Igawa, Emi; Ikeda, Shogo

    2006-09-08

    In Schizosaccharomyces pombe the repair of apurinic/apyrimidinic (AP) sites is mainly initiated by AP lyase activity of DNA glycosylase Nth1p. In contrast, the major AP endonuclease Apn2p functions by removing 3'-alpha,beta-unsaturated aldehyde ends induced by Nth1p, rather than by incising the AP sites. S. pombe possesses other minor AP endonuclease activities derived from Apn1p and Uve1p. In this study, we investigated the function of these two enzymes in base excision repair (BER) for methyl methanesulfonate (MMS) damage using the nth1 and apn2 mutants. Deletion of apn1 or uve1 from nth1Delta cells did not affect sensitivity to MMS. Exogenous expression of Apn1p failed to suppress the MMS sensitivity of nth1Delta cells. Although Apn1p and Uve1p incised the oligonucleotide containing an AP site analogue, these enzymes could not initiate repair of the AP sites in vivo. Despite this, expression of Apn1p partially restored the MMS sensitivity of apn2Delta cells, indicating that the enzyme functions as a 3'-phosphodiesterase to remove 3'-blocked ends. Localization of Apn1p in the nucleus and cytoplasm hints at an additional function of the enzyme other than nuclear DNA repair. Heterologous expression of Saccharomyces cerevisiae homologue of Apn1p completely restored the MMS resistance of the nth1Delta and apn2Delta cells. This result confirms a difference in the major pathway for processing the AP site between S. pombe and S. cerevisiae cells.

  4. Structure and Stability of ERCC1-XPF DNA Repair Complexes

    NARCIS (Netherlands)

    Faridounnia, M.

    2015-01-01

    Understanding DNA repair pathways such as Nucleotide Excision Repair, Double Strand Break repair and Interstrand Cross-Link repair is of basic interest for understanding fundamental cellular processes. It also forms the basis for understanding molecular details of diseases when defects occur in

  5. The Base Excision Repair system of Salmonella enterica serovar typhimurium counteracts DNA damage by host nitric oxide.

    Directory of Open Access Journals (Sweden)

    Anthony R Richardson

    2009-05-01

    Full Text Available Intracellular pathogens must withstand nitric oxide (NO. generated by host phagocytes. Salmonella enterica serovar Typhimurium interferes with intracellular trafficking of inducible nitric oxide synthase (iNOS and possesses multiple systems to detoxify NO.. Consequently, the level of NO. stress encountered by S. Typhimurium during infection in vivo has been unknown. The Base Excision Repair (BER system recognizes and repairs damaged DNA bases including cytosine and guanine residues modified by reactive nitrogen species. Apurinic/apyrimidinic (AP sites generated by BER glycosylases require subsequent processing by AP endonucleases. S. Typhimurium xth nfo mutants lacking AP endonuclease activity exhibit increased NO. sensitivity resulting from chromosomal fragmentation at unprocessed AP sites. BER mutant strains were thus used to probe the nature and extent of nitrosative damage sustained by intracellular bacteria during infection. Here we show that an xth nfo S. Typhimurium mutant is attenuated for virulence in C3H/HeN mice, and virulence can be completely restored by the iNOS inhibitor L-NIL. Inactivation of the ung or fpg glycosylase genes partially restores virulence to xth nfo mutant S. Typhimurium, demonstrating that NO. fluxes in vivo are sufficient to modify cytosine and guanine bases, respectively. Mutants lacking ung or fpg exhibit NO.-dependent hypermutability during infection, underscoring the importance of BER in protecting Salmonella from the genotoxic effects of host NO.. These observations demonstrate that host-derived NO. damages Salmonella DNA in vivo, and the BER system is required to maintain bacterial genomic integrity.

  6. Calcium-binding capacity of centrin2 is required for linear POC5 assembly but not for nucleotide excision repair.

    Directory of Open Access Journals (Sweden)

    Tiago J Dantas

    Full Text Available Centrosomes, the principal microtubule-organising centres in animal cells, contain centrins, small, conserved calcium-binding proteins unique to eukaryotes. Centrin2 binds to xeroderma pigmentosum group C protein (XPC, stabilising it, and its presence slightly increases nucleotide excision repair (NER activity in vitro. In previous work, we deleted all three centrin isoforms present in chicken DT40 cells and observed delayed repair of UV-induced DNA lesions, but no centrosome abnormalities. Here, we explore how centrin2 controls NER. In the centrin null cells, we expressed centrin2 mutants that cannot bind calcium or that lack sites for phosphorylation by regulatory kinases. Expression of any of these mutants restored the UV sensitivity of centrin null cells to normal as effectively as expression of wild-type centrin. However, calcium-binding-deficient and T118A mutants showed greatly compromised localisation to centrosomes. XPC recruitment to laser-induced UV-like lesions was only slightly slower in centrin-deficient cells than in controls, and levels of XPC and its partner HRAD23B were unaffected by centrin deficiency. Interestingly, we found that overexpression of the centrin interactor POC5 leads to the assembly of linear, centrin-dependent structures that recruit other centrosomal proteins such as PCM-1 and NEDD1. Together, these observations suggest that assembly of centrins into complex structures requires calcium binding capacity, but that such assembly is not required for centrin activity in NER.

  7. Deficiency in nucleotide excision repair family gene activity, especially ERCC3, is associated with non-pigmented hair fiber growth.

    Directory of Open Access Journals (Sweden)

    Mei Yu

    Full Text Available We conducted a microarray study to discover gene expression patterns associated with a lack of melanogenesis in non-pigmented hair follicles (HF by microarray. Pigmented and non-pigmented HFs were collected and micro-dissected into the hair bulb (HB and the upper hair sheaths (HS including the bulge region. In comparison to pigmented HS and HBs, nucleotide excision repair (NER family genes ERCC1, ERCC2, ERCC3, ERCC4, ERCC5, ERCC6, XPA, NTPBP, HCNP, DDB2 and POLH exhibited statistically significantly lower expression in non- pigmented HS and HBs. Quantitative PCR verified microarray data and identified ERCC3 as highly differentially expressed. Immunohistochemistry confirmed ERCC3 expression in HF melanocytes. A reduction in ERCC3 by siRNA interference in human melanocytes in vitro reduced their tyrosinase production ability. Our results suggest that loss of NER gene function is associated with a loss of melanin production capacity. This may be due to reduced gene transcription and/or reduced DNA repair in melanocytes which may eventually lead to cell death. These results provide novel information with regard to melanogenesis and its regulation.

  8. Modulation of proteostasis counteracts oxidative stress and affects DNA base excision repair capacity in ATM-deficient cells.

    Science.gov (United States)

    Poletto, Mattia; Yang, Di; Fletcher, Sally C; Vendrell, Iolanda; Fischer, Roman; Legrand, Arnaud J; Dianov, Grigory L

    2017-09-29

    Ataxia telangiectasia (A-T) is a syndrome associated with loss of ATM protein function. Neurodegeneration and cancer predisposition, both hallmarks of A-T, are likely to emerge as a consequence of the persistent oxidative stress and DNA damage observed in this disease. Surprisingly however, despite these severe features, a lack of functional ATM is still compatible with early life, suggesting that adaptation mechanisms contributing to cell survival must be in place. Here we address this gap in our knowledge by analysing the process of human fibroblast adaptation to the lack of ATM. We identify profound rearrangement in cellular proteostasis occurring very early on after loss of ATM in order to counter protein damage originating from oxidative stress. Change in proteostasis, however, is not without repercussions. Modulating protein turnover in ATM-depleted cells also has an adverse effect on the DNA base excision repair pathway, the major DNA repair system that deals with oxidative DNA damage. As a consequence, the burden of unrepaired endogenous DNA lesions intensifies, progressively leading to genomic instability. Our study provides a glimpse at the cellular consequences of loss of ATM and highlights a previously overlooked role for proteostasis in maintaining cell survival in the absence of ATM function. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  9. 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

    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...... cell lines used. However, the specific activities and cancer versus control comparison differed significantly between the nuclear and mitochondrial compartments. OGG1 activity, as measured by 8-oxodA incision, was up-regulated in cancer cell mitochondria but down-regulated in the nucleus when compared...

  10. Important anatomical structures used in paravaginal defect repair: cadaveric study.

    Science.gov (United States)

    Ersoy, Mehmet; Sagsoz, Nevin; Bozkurt, M Cem; Apaydin, Nihal; Elhan, Alaittin; Tekdemir, Ibrahim

    2004-02-10

    To examine the variations and the anatomical characteristics of the tendinous arch of pelvic fascia (TAPF), the tendinous arch of levator ani (TALA) and the obturator fascia (Ofa) that are important structures in paravaginal defect repair and their relations with important neurovascular structures. We carried our study on 10 pelvic halves of five female cadavers fixed in 10% formaldehyde. TALA could show a very high location or a low location near to inferior edge of obturator internus. TAPF was not observed in four of the cases. It was examined as a quite weak structure in two of the cases. The location of obturator vessel-nerve bundle could show difference. Obturator artery (OA) and vein sometimes do not course parallel to obturator vein (OV) and make an inclination and extend to the obturator foramen (OF). The distance between TAPF and the pectineal ligament (PL) (Cooper ligament) was measured as 5 cm on average. The distance between TAPF and the entrance of obturator canal was measured as 3.2 cm on average. While the distance of pudendal vessel-nerve bundle from levator ani (LA) at the anterior border of the spine was 0 mm, 2 cm anteriorly it was measured as 4.4 mm on average. Since TAPF does not develop in every case, it is not a safe structure to be used in surgery. If TALA develop downward as a variation, it could be difficult to distinguish from TAPF. Since the obturator fascia is a thin membrane, it is not a strong structure for suture placement. The region that is 2 cm in front of the ischial spine (IS) is a dangerous zone for pudendal vessel-nerve bundle.

  11. Defective repair of ionizing radiation damage in Cockayne`s syndrome and xeroderma pigmentosum group G

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, P.K. [Lawrence Berkeley Lab., CA (United States); Leadon, S.A. [Univ. of North Carolina, Chapel Hill, NC (United States)

    1994-12-31

    Damage produced by ultraviolet light (UV) or certain chemical carcinogens is repaired more rapidly in transcriptionally active DNA than in the genome as a whole by an evolutionarily conserved process coupled to transcription and involving preferential repair of transcribed strands. The generality of strand-specific repair for damage other than UV has not been well-established, but it has generally been assumed to involve the nucleotide excision repair pathway for bulky lesions. There is little overlap in the spectrum of lesions induced by ionizing radiation and UV; consistent with the idea that to a large extent, the repair processes for these two types of damage are separable, there are very few mammalian cell mutants that are hypersensitive to the lethal effects of both.

  12. 49 CFR 195.230 - Welds: Repair or removal of defects.

    Science.gov (United States)

    2010-10-01

    ... offshore pipeline being installed from a pipelay vessel, a weld must be removed if it has a crack that is... must be inspected to ensure its acceptability. (c) Repair of a crack, or of any defect in a previously... welding procedure used to make the original weld are met upon completion of the final weld repair. [Amdt...

  13. Novel technique for closure of defect in laparoscopic ventral hernia repair

    Directory of Open Access Journals (Sweden)

    Sharma Deborshi

    2010-01-01

    Full Text Available Laparoscopic repair of ventral hernia is the standard of care in today`s era. With increasing experience, different theories and techniques have been described by different authors to overcome the intraoperative and postoperative problems. We describe a novel technique for closure of defect in laparoscopic hernia repair which has the added advantage.

  14. Effect of load on the repair of osteochondral defects using a porous polymer scaffold

    NARCIS (Netherlands)

    Hannink, G.; Mulder, E.L. de; Tienen, T.G. van; Buma, P.

    2012-01-01

    The aim of the present study was to evaluate if a porous polymer scaffold, currently used for partial meniscal replacement in clinical practice, could initiate regeneration and repair of osteochondral defects, and if regeneration and repair were related to mechanical stimulation. Two equally sized

  15. Differential contributory roles of nucleotide excision and homologous recombination repair for enhancing cisplatin sensitivity in human ovarian cancer cells

    Directory of Open Access Journals (Sweden)

    Wani Gulzar

    2011-03-01

    Full Text Available Abstract Background While platinum-based chemotherapeutic agents are widely used to treat various solid tumors, the acquired platinum resistance is a major impediment in their successful treatment. Since enhanced DNA repair capacity is a major factor in conferring cisplatin resistance, targeting of DNA repair pathways is an effective stratagem for overcoming cisplatin resistance. This study was designed to delineate the role of nucleotide excision repair (NER, the principal mechanism for the removal of cisplatin-induced DNA intrastrand crosslinks, in cisplatin resistance and reveal the impact of DNA repair interference on cisplatin sensitivity in human ovarian cancer cells. Results We assessed the inherent NER efficiency of multiple matched pairs of cisplatin-sensitive and -resistant ovarian cancer cell lines and their expression of NER-related factors at mRNA and protein levels. Our results showed that only the cisplatin-resistant ovarian cancer cell line PEO4 possessed an increased NER capacity compared to its inherently NER-inefficient parental line PEO1. Several other cisplatin-resistant cell lines, including CP70, CDDP and 2008C13, exhibited a normal and parental cell-comparable NER capacity for removing cisplatin-induced DNA intrastrand cross-links (Pt-GG. Concomitant gene expression analysis revealed discordance in mRNA and protein levels of NER factors in various ovarian cancer cell lines and NER proteins level were unrelated to the cisplatin sensitivity of these cell lines. Although knockdown of NER factors was able to compromise the NER efficiency, it only caused a minimal effect on cisplatin sensitivity. On the contrary, downregulation of BRCA2, a critical protein for homologous recombination repair (HRR, significantly enhanced the efficacy of cisplatin in killing ovarian cancer cell line PEO4. Conclusion Our studies indicate that the level of NER factors in ovarian cancer cell lines is neither a determinant of their NER capacity nor

  16. Repair or replacement of defective restorations by dentists in The Dental Practice-Based Research Network

    DEFF Research Database (Denmark)

    Gordan, Valeria V; Riley, Joseph L; Geraldeli, Saulo

    2012-01-01

    The authors aimed to determine whether dentists in practices belonging to The Dental Practice-Based Research Network (DPBRN) were more likely to repair or to replace a restoration that they diagnosed as defective; to quantify dentists' specific reasons for repairing or replacing restorations......; and to test the hypothesis that certain dentist-, patient- and restoration-related variables are associated with the decision between repairing and replacing restorations....

  17. UV-induced de novo protein synthesis enhances nucleotide excision repair efficiency in a transcription-dependent manner in S. cerevisiae.

    Science.gov (United States)

    Al-Moghrabi, Nisreen M; Al-Sharif, Ibtehaj S; Aboussekhra, Abdelilah

    2003-11-21

    DNA damage results in the up-regulation of several genes involved in different cellular physiological processes, such as the nucleotide excision repair (NER) mechanism that copes with a broad range of DNA alterations, including the carcinogenic ultraviolet (UV) light-induced pyrimidine dimers (PDs). There are two NER sub-pathways: transcription coupled repair (TCR) that is specific for the transcribed strands (TS) of active genes and global genomic repair (GGR) that repairs non-transcribed DNA sequences (NTD) and the non-transcribed strands (NTS) of expressed genes. To elucidate the role of UV-dependent de novo protein synthesis in nucleotide excision repair in the budding yeast, we investigated the effect of the protein synthesis inhibitor, cycloheximide, on the removal of PDs. Log phase as well as G(1)-synchronized cells were treated with the drug shortly before UV irradiation and immediately thereafter, and the repair of damaged DNA was assessed with the high resolution primer extension technique. The results show that in both cellular conditions, the inhibition of UV-dependent de novo protein synthesis by cycloheximide impairs the excision repair of the transcriptionally active GAL10 and URA3 genes, with a greater effect on the non-transcribed strands. This indicates that UV-mediated de novo protein synthesis is required for efficient nucleotide excision repair, but not for the preferential repair of the TSs. On the other hand, cycloheximide did not affect the repair of either strand of the repressed GAL10 gene or the non-transcribed promoter region of the URA3 gene, showing that UV-induced de novo protein synthesis is not required for PD removal from transcriptionally inactive DNA sequences. Together, these data show that despite the fact that NTD and NTSs are normally repaired by the GGR sub-pathway, their requirement for UV-dependent de novo protein synthesis is different, which may suggest a difference in the processing of UV lesions in these non

  18. Differential participation of homologous recombination and nucleotide excision repair in yeast survival to ultraviolet light radiation.

    Science.gov (United States)

    Toussaint, Martin; Wellinger, Raymund J; Conconi, Antonio

    2010-04-30

    The purpose of this research was to assess the ultraviolet light (UV) phenotype of yeast sirDelta cells vs. WT cells, and to determine whether de-silenced chromatin or the intrinsic pseudoploidy of sirDelta mutants contributes to their response to UV. Additional aims were to study the participation of HR and NER in promoting UV survival during the cell cycle, and to define the extent of the co-participation for both repair pathways. The sensitivity of yeast Saccharomyces cerevisiae to UV light was determined using a method based on automatic measurements of optical densities of very small (100mul) liquid cell cultures. We show that pseudo-diploidy of sirDelta strains promotes resistance to UV irradiation and that HR is the main mechanism that is responsible for this phenotype. In addition, HR together with GG-NER renders cells in the G2-phase of the cell cycle more resistant to UV irradiation than cells in the G1-phase, which underscore the importance of HR when two copies of the chromosomes are present. Nevertheless, in asynchronously growing cells NER is the main repair pathway that responds to UV induced DNA damage. This study provides detailed and quantitative information on the co-participation of HR and NER in UV survival of yeast cells. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

  19. The Mutyh base excision repair gene influences the inflammatory response in a mouse model of ulcerative colitis.

    Directory of Open Access Journals (Sweden)

    Ida Casorelli

    Full Text Available BACKGROUND: The Mutyh DNA glycosylase is involved in the repair of oxidized DNA bases. Mutations in the human MUTYH gene are responsible for colorectal cancer in familial adenomatous polyposis. Since defective DNA repair genes might contribute to the increased cancer risk associated with inflammatory bowel diseases, we compared the inflammatory response of wild-type and Mutyh(-/- mice to oxidative stress. METHODOLOGY/PRINCIPAL FINDINGS: The severity of colitis, changes in expression of genes involved in DNA repair and inflammation, DNA 8-oxoguanine levels and microsatellite instability were analysed in colon of mice treated with dextran sulfate sodium (DSS. The Mutyh(-/- phenotype was associated with a significant accumulation of 8-oxoguanine in colon DNA of treated mice. A single DSS cycle induced severe acute ulcerative colitis in wild-type mice, whereas lesions were modest in Mutyh(-/- mice, and this was associated with moderate variations in the expression of several cytokines. Eight DSS cycles caused chronic colitis in both wild-type and Mutyh(-/- mice. Lymphoid hyperplasia and a significant reduction in Foxp3(+ regulatory T cells were observed only in Mutyh(-/- mice. CONCLUSIONS: The findings indicate that, in this model of ulcerative colitis, Mutyh plays a major role in maintaining intestinal integrity by affecting the inflammatory response.

  20. Evaluation of porcine hydrated dermis augmented repair in a fascial defect model.

    Science.gov (United States)

    Hackett, Eileen S; Harilal, Dina; Bowley, Chris; Hawes, Michael; Turner, A Simon; Goldman, Scott M

    2011-01-01

    Surgical mesh composed of extracellular matrix promotes healing of difficult soft tissue and orthopedic repairs in preclinical and clinical trials. In this study, a novel extracellular matrix prepared from porcine hydrated dermis was evaluated in an in vivo fascial defect model in sheep. Fascial defects were created, and then acutely repaired with surgical mesh. Healed surgical sites were evaluated grossly, histologically, and biomechanically at 6 and 12 weeks. Porcine hydrated dermis extracellular matrix performed favorably compared to negative control empty defects and native fascia, with minimal gross adhesion, low histologic inflammatory scores, and significantly greater tensile strength of the healing surgical site when compared with native fascia. © 2010 Wiley Periodicals, Inc.

  1. Robotic-assisted Laparoscopic Repair of a Cesarean Section Scar Defect.

    Science.gov (United States)

    Mahmoud, Mohamad S; Nezhat, Farr R

    2015-01-01

    To describe our technique for the repair of a cesarean section uterine scar defect after removal of an ectopic pregnancy from the scar in a patient desiring future pregnancies. Step-by-step explanation of the procedure using video (Canadian Task Force classification III). Uterine scar dehiscence/defect is a known complications of multiple cesarean deliveries that can result in abnormal bleeding, infertility, and cesarean scar ectopic pregnancy. With the increasing number of cesarean sections performed in the United States, the prevalence of this complication is rising. Nonetheless, there currently are no standardized surgical treatment guidelines available to manage this pathology through a minimally invasive approach. In this video, we describe our technique for the surgical management of a symptomatic cesarean section scar defect. We performed a robotic-assisted laparoscopic repair of this defect in a 40-year-old G4P3013 with a recent cesarean section scar ectopic pregnancy managed by endometrial curettage, with subsequent persistent abnormal vaginal bleeding. A repeat ultrasound revealed a low uterine segment defect consistent with dehiscence. She was referred to us because she desired a conservative treatment given her desire for future pregnancies. The defect was localized by hysteroscopy and laparoscopy after developing the bladder flap. The scar tissue around the defect was resected, and the freshened edges of the defect were closed using delayed absorbable suture. Chromopertubation confirmed the watertightness of the repair. Postoperatively, the patient had regular normal periods, and her hysterosalpingogram didn't show any uterine defect. Robotic-assisted laparoscopic repair of cesarean section scar defect is a feasible and safe procedure when done with respect to anatomy and following sound surgical technique. With the increasing number of cesarean sections, gynecologists will be dealing with this pathology more frequently, and need to become more

  2. UvrD Participation in Nucleotide Excision Repair Is Required for the Recovery of DNA Synthesis following UV-Induced Damage in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Kelley N. Newton

    2012-01-01

    Full Text Available UvrD is a DNA helicase that participates in nucleotide excision repair and several replication-associated processes, including methyl-directed mismatch repair and recombination. UvrD is capable of displacing oligonucleotides from synthetic forked DNA structures in vitro and is essential for viability in the absence of Rep, a helicase associated with processing replication forks. These observations have led others to propose that UvrD may promote fork regression and facilitate resetting of the replication fork following arrest. However, the molecular activity of UvrD at replication forks in vivo has not been directly examined. In this study, we characterized the role UvrD has in processing and restoring replication forks following arrest by UV-induced DNA damage. We show that UvrD is required for DNA synthesis to recover. However, in the absence of UvrD, the displacement and partial degradation of the nascent DNA at the arrested fork occur normally. In addition, damage-induced replication intermediates persist and accumulate in uvrD mutants in a manner that is similar to that observed in other nucleotide excision repair mutants. These data indicate that, following arrest by DNA damage, UvrD is not required to catalyze fork regression in vivo and suggest that the failure of uvrD mutants to restore DNA synthesis following UV-induced arrest relates to its role in nucleotide excision repair.

  3. Cockayne syndrome--a primary defect in DNA repair, transcription, both or neither?

    Science.gov (United States)

    Friedberg, E C

    1996-09-01

    Cockayne syndrome is a rare autosomal recessive disease characterized by a complex clinical phenotype. Most Cockayne syndrome cells are hypersensitive to killing by ultraviolet radiation. This observation has prompted a wealth of studies on the DNA repair capacity of Cockayne syndrome cells in vitro. Many studies support the notion that such cells are defective in a DNA repair mode(s) that is transcription-dependent. However, it remains to be established that this is a primary molecular defect in Cockayne syndrome cells and that it explains the complex clinical phenotype associated with the disease. An alternative hypothesis is that Cockayne syndrome cells have a defect in transcription affecting the expression of certain genes, which is compatible with embryogenesis but not with normal post-natal development. Defective transcription may impair the normal processing of DNA damage during transcription-dependent repair.

  4. Initial steps of the base excision repair pathway within the nuclear architecture; Les etapes initiales du mecanisme de reparation par excision de bases au sein de l'architecture nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Amouroux, R

    2009-09-15

    Oxidative stress induced lesions threaten aerobic organisms by representing a major cause of genomic instability. A common product of guanine oxidation, 8-oxo-guanine (8- oxoG) is particularly mutagenic by provoking G to T transversions. Removal of oxidised bases from DNA is initiated by the recognition and excision of the damaged base by a DNA glycosylase, initiating the base excision repair (BER) pathway. In mammals, 8-oxoG is processed by the 8-oxoG-DNA-glycosylase I (OGG1), which biochemical mechanisms has been well characterised in vitro. However how and where this enzyme finds the modified base within the complex chromatin architecture is not yet understood. We show that upon induction of 8-oxoG, OGG1, together with at least two other proteins involved in BER, is recruited from a soluble fraction to chromatin. Formation kinetics of this patches correlates with 8-oxoG excision, suggesting a direct link between presence of this chromatin-associated complexes and 8-oxoG repair. More precisely, these repair patches are specifically directed to euchromatin regions, and completely excluded from heterochromatin regions. Inducing of artificial chromatin compaction results in a complete inhibition of the in vivo repair of 8-oxoG, probably by impeding the access of OGG1 to the lesion. Using OGG1 mutants, we show that OGG1 direct recognition of 8-oxoG did not trigger its re-localisation to the chromatin. We conclude that in response to the induction of oxidative DNA damage, the DNA glycosylase is actively recruited to regions of open chromatin allowing the access of the BER machinery to the lesions. (author)

  5. The role of the PHP domain associated with DNA polymerase X from Thermus thermophilus HB8 in base excision repair.

    Science.gov (United States)

    Nakane, Shuhei; Nakagawa, Noriko; Kuramitsu, Seiki; Masui, Ryoji

    2012-11-01

    Base excision repair (BER) is one of the most commonly used DNA repair pathways involved in genome stability. X-family DNA polymerases (PolXs) play critical roles in BER, especially in filling single-nucleotide gaps. In addition to a polymerase core domain, bacterial PolXs have a polymerase and histidinol phosphatase (PHP) domain with phosphoesterase activity which is also required for BER. However, the role of the PHP domain of PolX in bacterial BER remains unresolved. We found that the PHP domain of Thermus thermophilus HB8 PolX (ttPolX) functions as two types of phosphoesterase in BER, including a 3'-phosphatase and an apurinic/apyrimidinic (AP) endonuclease. Experiments using T. thermophilus HB8 cell lysates revealed that the majority of the 3'-phosphatase and AP endonuclease activities are attributable to the another phosphoesterase in T. thermophilus HB8, endonuclease IV (ttEndoIV). However, ttPolX possesses significant 3'-phosphatase activity in ΔttendoIV cell lysate, indicating possible complementation. Our experiments also reveal that there are only two enzymes that display the 3'-phosphatase activity in the T. thermophilus HB8 cell, ttPolX and ttEndoIV. Furthermore, phenotypic analysis of ΔttpolX, ΔttendoIV, and ΔttpolX/ΔttendoIV using hydrogen peroxide and sodium nitrite supports the hypothesis that ttPolX functions as a backup for ttEndoIV in BER. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Modulation of radiation-induced base excision repair pathway gene expression by melatonin

    Directory of Open Access Journals (Sweden)

    Saeed Rezapoor

    2017-01-01

    Full Text Available Objective: Approximately 70% of all cancer patients receive radiotherapy. Although radiotherapy is effective in killing cancer cells, it has adverse effects on normal cells as well. Melatonin (MLT as a potent antioxidant and anti-inflammatory agent has been proposed to stimulate DNA repair capacity. We investigated the capability of MLT in the modification of radiation-induced DNA damage in rat peripheral blood cells. Materials and Methods: In this experimental study, male rats (n = 162 were divided into 27 groups (n = 6 in each group including: irradiation only, vehicle only, vehicle with irradiation, 100 mg/kg MLT alone, 100 mg/kg MLT plus irradiation in 3 different time points, and control. Subsequently, they were irradiated with a single whole-body X-ray radiation dose of 2 and 8 Gy at a dose rate of 200 MU/min. Rats were given an intraperitoneal injection of MLT or the same volume of vehicle alone 1 h prior to irradiation. Blood samples were also taken 8, 24, and 48 h postirradiation, in order to measure the 8-oxoguanine glycosylase1 (Ogg1, Apex1, and Xrcc1 expression using quantitative real-time-polymerase chain reaction. Results: Exposing to the ionizing radiation resulted in downregulation of Ogg1, Apex1, and Xrcc1 gene expression. The most obvious suppression was observed in 8 h after exposure. Pretreatments with MLT were able to upregulate these genes when compared to the irradiation-only and vehicle plus irradiation groups (P < 0.05 in all time points. Conclusion: Our results suggested that MLT in mentioned dose may result in modulation of Ogg1, Apex1, and Xrcc1 gene expression in peripheral blood cells to reduce X-ray irradiation-induced DNA damage. Therefore, administration of MLT may increase the normal tissue tolerance to radiation through enhancing the cell DNA repair capacity. We believed that MLT could play a radiation toxicity reduction role in patients who have undergone radiation treatment as a part of cancer radiotherapy.

  7. Up-regulation of nucleotide excision repair in mouse lung and liver following chronic exposure to aflatoxin B{sub 1} and its dependence on p53 genotype

    Energy Technology Data Exchange (ETDEWEB)

    Mulder, Jeanne E. [Pharmacology and Toxicology Graduate Program, Department of Biomedical and Molecular Sciences, Queen' s University Kingston, Ontario K7L 3N6 (Canada); Bondy, Genevieve S.; Mehta, Rekha [Toxicology Research Division, 2202D, Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario K1A 0K9 (Canada); Massey, Thomas E., E-mail: masseyt@queensu.ca [Pharmacology and Toxicology Graduate Program, Department of Biomedical and Molecular Sciences, Queen' s University Kingston, Ontario K7L 3N6 (Canada)

    2014-03-01

    Aflatoxin B{sub 1} (AFB{sub 1}) is biotransformed in vivo into an epoxide metabolite that forms DNA adducts that may induce cancer if not repaired. p53 is a tumor suppressor gene implicated in the regulation of global nucleotide excision repair (NER). Male heterozygous p53 knockout (B6.129-Trp53{sup tm1Brd}N5, Taconic) and wild-type mice were exposed to 0, 0.2 or 1.0 ppm AFB{sub 1} for 26 weeks. NER activity was assessed with an in vitro assay, using AFB{sub 1}-epoxide adducted plasmid DNA as a substrate. For wild-type mice, repair of AFB{sub 1}–N7-Gua adducts was 124% and 96% greater in lung extracts from mice exposed to 0.2 ppm and 1.0 ppm AFB{sub 1} respectively, and 224% greater in liver extracts from mice exposed to 0.2 ppm AFB{sub 1} (p < 0.05). In heterozygous p53 knockout mice, repair of AFB{sub 1}–N7-Gua was only 45% greater in lung extracts from mice exposed to 0.2 ppm AFB{sub 1} (p < 0.05), and no effect was observed in lung extracts from mice treated with 1.0 ppm AFB{sub 1} or in liver extracts from mice treated with either AFB{sub 1} concentration. p53 genotype did not affect basal levels of repair. AFB{sub 1} exposure did not alter repair of AFB{sub 1}-derived formamidopyrimidine adducts in lung or liver extracts of either mouse genotype nor did it affect XPA or XPB protein levels. In summary, chronic exposure to AFB{sub 1} increased NER activity in wild-type mice, and this response was diminished in heterozygous p53 knockout mice, indicating that loss of one allele of p53 limits the ability of NER to be up-regulated in response to DNA damage. - Highlights: • Mice are chronically exposed to low doses of the mycotoxin aflatoxin B{sub 1} (AFB{sub 1}). • The effects of AFB{sub 1} and p53 status on nucleotide excision repair are investigated. • AFB{sub 1} increases nucleotide excision repair in wild type mouse lung and liver. • This increase is attenuated in p53 heterozygous mouse lung and liver. • Results portray the role of p53 in

  8. C. elegans lifespan extension by osmotic stress requires FUdR, base excision repair, FOXO, and sirtuins

    Science.gov (United States)

    Anderson, Edward N; Corkins, Mark E; Li, Jia-Cheng; Singh, Komudi; Parsons, Sadé; Tucey, Tim M; Sorkaç, Altar; Huang, Huiyan; Dimitriadi, Maria; Sinclair, David A

    2016-01-01

    Moderate stress can increase lifespan by hormesis, a beneficial low-level induction of stress response pathways. 5’-fluorodeoxyuridine (FUdR) is commonly used to sterilize Caenorhabditis elegans in aging experiments. However, FUdR alters lifespan in some genotypes and induces resistance to thermal and proteotoxic stress. We report that hypertonic stress in combination with FUdR treatment or inhibition of the FUdR target thymidylate synthase, TYMS-1, extends C. elegans lifespan by up to 30%. By contrast, in the absence of FUdR, hypertonic stress decreases lifespan. Adaptation to hypertonic stress requires diminished Notch signaling and loss of Notch co-ligands leads to lifespan extension only in combination with FUdR. Either FUdR treatment or TYMS-1 loss induced resistance to acute hypertonic stress, anoxia, and thermal stress. FUdR treatment increased expression of DAF-16 FOXO and the osmolyte biosynthesis enzyme GPDH-1. FUdR-induced hypertonic stress resistance was partially dependent on sirtuins and base excision repair (BER) pathways, while FUdR-induced lifespan extension under hypertonic stress conditions requires DAF-16, BER, and sirtuin function. Combined, these results demonstrate that FUdR, through inhibition of TYMS-1, activates stress response pathways in somatic tissues to confer hormetic resistance to acute and chronic stress. C. elegans lifespan studies using FUdR may need re-interpretation in light of this work. PMID:26854551

  9. The nucleotide excision repair (NER) system of Helicobacter pylori: role in mutation prevention and chromosomal import patterns after natural transformation.

    Science.gov (United States)

    Moccia, Claudia; Krebes, Juliane; Kulick, Stefan; Didelot, Xavier; Kraft, Christian; Bahlawane, Christelle; Suerbaum, Sebastian

    2012-05-06

    Extensive genetic diversity and rapid allelic diversification are characteristics of the human gastric pathogen Helicobacter pylori, and are believed to contribute to its ability to cause chronic infections. Both a high mutation rate and frequent imports of short fragments of exogenous DNA during mixed infections play important roles in generating this allelic diversity. In this study, we used a genetic approach to investigate the roles of nucleotide excision repair (NER) pathway components in H. pylori mutation and recombination. Inactivation of any of the four uvr genes strongly increased the susceptibility of H. pylori to DNA damage by ultraviolet light. Inactivation of uvrA and uvrB significantly decreased mutation frequencies whereas only the uvrA deficient mutant exhibited a significant decrease of the recombination frequency after natural transformation. A uvrC mutant did not show significant changes in mutation or recombination rates; however, inactivation of uvrC promoted the incorporation of significantly longer fragments of donor DNA (2.2-fold increase) into the recipient chromosome. A deletion of uvrD induced a hyper-recombinational phenotype. Our data suggest that the NER system has multiple functions in the genetic diversification of H. pylori, by contributing to its high mutation rate, and by controlling the incorporation of imported DNA fragments after natural transformation.

  10. Instability of CTG Repeats is Governed by the Position of a DNA Base Lesion through Base Excision Repair

    Science.gov (United States)

    Zhang, Zunzhen; Liu, Yuan

    2013-01-01

    Trinucleotide repeat (TNR) expansions and deletions are associated with human neurodegeneration and cancer. However, their underlying mechanisms remain to be elucidated. Recent studies have demonstrated that CAG repeat expansions can be initiated by oxidative DNA base damage and fulfilled by base excision repair (BER), suggesting active roles for oxidative DNA damage and BER in TNR instability. Here, we provide the first evidence that oxidative DNA damage can induce CTG repeat deletions along with limited expansions in human cells. Biochemical characterization of BER in the context of (CTG)20 repeats further revealed that repeat instability correlated with the position of a base lesion in the repeat tract. A lesion located at the 5′-end of CTG repeats resulted in expansion, whereas a lesion located either in the middle or the 3′-end of the repeats led to deletions only. The positioning effects appeared to be determined by the formation of hairpins at various locations on the template and the damaged strands that were bypassed by DNA polymerase β and processed by flap endonuclease 1 with different efficiency. Our study indicates that the position of a DNA base lesion governs whether TNR is expanded or deleted through BER. PMID:23468897

  11. DNA Base-Excision Repair Genes OGG1 and NTH1 in Brazilian Lung Cancer Patients.

    Science.gov (United States)

    Couto, Patricia G; Bastos-Rodrigues, Luciana; Carneiro, Juliana G; Guieiro, Fernanda; Bicalho, Maria Aparecida; Leidenz, Franciele B; Bicalho, Ana J; Friedman, Eitan; De Marco, Luiz

    2015-12-01

    Lung cancer is the leading global cause of cancer-related mortality and is associated with poor prognosis. To improve survival rates of lung cancer patients, better understanding of tumorigenic mechanisms is necessary, which may lead to development of new therapeutic strategies. The hOGG1 and NTH1 genes act in the DNA BER repair pathway and their involvement in lung cancer pathogenesis has been analyzed in several populations. We analyzed targeted regions of the hOGG1 and NTH1 genes in 96 Brazilian patients with non-small-cell lung cancer (NSCLC) and 89 cancer-free, ethnically matched controls. The NTH1 c.98G>T polymorphism rs2302172 (p = 0.02 and p = 0.02 for allele and genotype frequency between cases and controls, respectively) and the 140-17C> T variant (rs2233518) (p = 0.02 and p = 0.02 for allele and genotype frequency between cases and controls, respectively) were detected in four lung cancer cases (4 %) while the NTH1 Q131K (C391A) polymorphism was found in seven lung cancer cases (7 %) (p = 0.001 and p = 0.008, for allele and genotype frequency between cases and controls, respectively). None of these sequence variants were detected in controls. The Ser326Cys (C1245G, rs1052133) polymorphism in the OGG1 gene was detected in 42 % of analyzed NSCLC patients and in 34 % of the controls (p = 0.11 and p = 0.25 for allele and genotype frequency between cases and controls, respectively). Our study provides preliminary evidence that polymorphisms in OGG1 do not contribute to development of NSCLC in Brazilian patients and that NTH1 polymorphisms may be associated with NSCLC pathogenesis.

  12. Treatment experience of surgical repair for long-term skull defect

    Directory of Open Access Journals (Sweden)

    Shou-cheng FAN

    2015-12-01

    Full Text Available Retrospective analysis was performed on 30 patients of skull defect who underwent surgical repair. Intraoperative and postoperative curative effect was evaluated on those patients, and the results showed that the incidence rate of intraoperative dura mater defect (P = 0.001, early postoperative complications [new epilepsy (P = 0.035 and effusion (P = 0.021] and late postoperative complications [foreign body sensation (P = 0.035 and dizziness and headache (P = 0.050] in long-term skull defect group were all higher than those in control group. In conclusion, surgical repair of long-term skull defect incurring high risk and various complications will not be an ideal management. Therefore, early surgical treatment for skull defect is suggested. DOI: 10.3969/j.issn.1672-6731.2015.12.016

  13. Role of the DNA Base Excision Repair Protein, APE1 in Cisplatin, Oxaliplatin, or Carboplatin Induced Sensory Neuropathy

    Science.gov (United States)

    Kelley, Mark R.; Jiang, Yanlin; Guo, Chunlu; Reed, April; Meng, Hongdi; Vasko, Michael R.

    2014-01-01

    Although chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting side effect of platinum drugs, the mechanisms of this toxicity remain unknown. Previous work in our laboratory suggests that cisplatin-induced CIPN is secondary to DNA damage which is susceptible to base excision repair (BER). To further examine this hypothesis, we studied the effects of cisplatin, oxaliplatin, and carboplatin on cell survival, DNA damage, ROS production, and functional endpoints in rat sensory neurons in culture in the absence or presence of reduced expression of the BER protein AP endonuclease/redox factor-1 (APE1). Using an in situ model of peptidergic sensory neuron function, we examined the effects of the platinum drugs on hind limb capsaicin-evoked vasodilatation. Exposing sensory neurons in culture to the three platinum drugs caused a concentration-dependent increase in apoptosis and cell death, although the concentrations of carboplatin were 10 fold higher than cisplatin. As previously observed with cisplatin, oxaliplatin and carboplatin also increased DNA damage as indicated by an increase in phospho-H2AX and reduced the capsaicin-evoked release of CGRP from neuronal cultures. Both cisplatin and oxaliplatin increased the production of ROS as well as 8-oxoguanine DNA adduct levels, whereas carboplatin did not. Reducing levels of APE1 in neuronal cultures augmented the cisplatin and oxaliplatin induced toxicity, but did not alter the effects of carboplatin. Using an in vivo model, systemic injection of cisplatin (3 mg/kg), oxaliplatin (3 mg/kg), or carboplatin (30 mg/kg) once a week for three weeks caused a decrease in capsaicin-evoked vasodilatation, which was delayed in onset. The effects of cisplatin on capsaicin-evoked vasodilatation were attenuated by chronic administration of E3330, a redox inhibitor of APE1 that serendipitously enhances APE1 DNA repair activity in sensory neurons. These outcomes support the importance of the BER pathway, and particularly APE

  14. A ubiquitylation site in Cockayne syndrome B required for repair of oxidative DNA damage, but not for transcription-coupled nucleotide excision repair.

    Science.gov (United States)

    Ranes, Michael; Boeing, Stefan; Wang, Yuming; Wienholz, Franziska; Menoni, Hervé; Walker, Jane; Encheva, Vesela; Chakravarty, Probir; Mari, Pierre-Olivier; Stewart, Aengus; Giglia-Mari, Giuseppina; Snijders, Ambrosius P; Vermeulen, Wim; Svejstrup, Jesper Q

    2016-06-20

    Cockayne syndrome B (CSB), best known for its role in transcription-coupled nucleotide excision repair (TC-NER), contains a ubiquitin-binding domain (UBD), but the functional connection between protein ubiquitylation and this UBD remains unclear. Here, we show that CSB is regulated via site-specific ubiquitylation. Mass spectrometry analysis of CSB identified lysine (K) 991 as a ubiquitylation site. Intriguingly, mutation of this residue (K991R) does not affect CSB's catalytic activity or protein stability, but greatly affects genome stability, even in the absence of induced DNA damage. Moreover, cells expressing CSB K991R are sensitive to oxidative DNA damage, but proficient for TC-NER. K991 becomes ubiquitylated upon oxidative DNA damage, and while CSB K991R is recruited normally to such damage, it fails to dissociate in a timely manner, suggesting a requirement for K991 ubiquitylation in CSB activation. Interestingly, deletion of CSB's UBD gives rise to oxidative damage sensitivity as well, while CSB ΔUBD and CSB K991R affects expression of overlapping groups of genes, further indicating a functional connection. Together, these results shed new light on the regulation of CSB, with K991R representing an important separation-of-function-mutation in this multi-functional protein. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  15. Primary reconstruction of neck defect after excision of metastatic melanoma of unknown primary site with regional pectoral myocutaneous flap

    Directory of Open Access Journals (Sweden)

    Veličkov Asen

    2016-01-01

    Full Text Available Introduction. Metastatic melanoma of unknown primary (MMUP is already a well described oncologic phenomenon in the literature, whereas tissue defects’ reconstructions on the neck region always present a challenge for the reconstructive surgeon. Two cases of giant metastatic, skin infiltrative neck tumor masses are presented. In both cases MMUP was diagnosed. Both intraoperative tissue defects were reconstructed using pectoralis major (PM regional flap. Outline of cases. The first patient was admitted with giant tumor mass on the right side of the neck. The fast growing mass appeared two months prior to the admission. Thorough examination showed no signs of primary tumor. Removal surgery was performed and the defect was reconstructed using the PM musculocutaneous flap. The second patient was admitted with large tumor mass on the left side of the neck. Thorough examination displayed no signs of any primary tumor. After the excision, the tumor mass and subsequent neck dissection, reconstruction followed, using the pedicled PM muscle flap and partial thickness skin transplants. There were no major complications in either case. The histopathological examinations presented metastatic melanoma diagnoses. Conclusion. Clinical outcome of MMUP described in literature is rather variable. Different studies have shown that prognosis in patients with MMUP is better than that in patients with diagnosed primary melanoma with metastatic disease. Therefore, the best initial course of action in those cases would be surgery, according to oncological principles, if possible. Neck defects’ reconstructions should fulfill both functional and esthetic demands. Due to the reliability and low cost of the procedure, PM regional flap presents a very good and trustworthy reconstruction modality.

  16. Evidence that the Rad1 and Rad10 proteins of Saccharomyces cerevisiae participate as a complex in nucleotide excision repair of UV radiation damage.

    OpenAIRE

    Siede, W.; Friedberg, A S; Friedberg, E C

    1993-01-01

    A newly characterized rad1 missense mutation (rad1-20) in the yeast Saccharomyces cerevisiae maps to a region of the Rad1 polypeptide known to be required for Rad1-Rad10 complex formation. The UV sensitivity of the rad1-20 mutant can be partially and specifically corrected by overexpression of wild-type Rad10 protein. These results suggest that complex formation between the Rad1 and Rad10 proteins is required for nucleotide excision repair.

  17. Intramural Ventricular Septal Defect Is a Distinct Clinical Entity Associated With Postoperative Morbidity in Children After Repair of Conotruncal Anomalies

    National Research Council Canada - National Science Library

    Patel, Jyoti K; Glatz, Andrew C; Ghosh, Reena M; Jones, Shannon M; Natarajan, Shobha; Ravishankar, Chitra; Mascio, Christopher E; Spray, Thomas L; Cohen, Meryl S

    2015-01-01

    BACKGROUND—Intramural ventricular septal defects (VSDs) are interventricular communications through right ventricular free wall trabeculations that can occur after repair of conotruncal anomalies...

  18. The NR4A2 nuclear receptor is recruited to novel nuclear foci in response to UV irradiation and participates in nucleotide excision repair.

    Directory of Open Access Journals (Sweden)

    Kasturee Jagirdar

    Full Text Available Ultraviolet radiation (UVR is one of the most common mutagens encountered by humans and induces the formation of cyclobutane pyrimidine dimers (CPDs and pyrimidine-(6-4-pyrimidone photoproduct (6-4PP lesions in the genomic DNA. To prevent the accumulation of deleterious mutations these lesions must be efficiently repaired, primarily by nucleotide excision repair. We have previously demonstrated that the NR4A family of nuclear receptors are crucial mediators of the DNA repair function of the MC1R signalling pathway in melanocytes. Here we explore the role of the NR4A2 protein in the DNA repair process further. Using EYFP tagged-NR4A2 we have demonstrated a UVR induced recruitment to distinct nuclear foci where they co-localise with known DNA repair proteins. We reveal that the N-terminal domain of the receptor is required for this translocation and identify a role for p38 and PARP signalling in this process. Moreover disruption of the functional integrity of the Ligand Binding Domain of the receptor by deleting the terminal helix 12 effectively blocks co-localisation of the receptor with DNA repair factors. Restored co-localisation of the mutant receptor with DNA repair proteins in the presence of a Histone Deacetylase Inhibitor suggests that impaired chromatin accessibility underpins the mis-localisation observed. Finally NR4A2 over-expression facilitated a more efficient clearance of UVR induced CPD and 6-4PP lesions. Taken together these data uncover a novel role for the NR4A nuclear receptors as direct facilitators of nucleotide excision repair.

  19. Robot-Assisted Partial Atrioventricular Canal Defect Repair and Cryo-Maze Procedure.

    Science.gov (United States)

    Mandal, Kaushik; Srivastava, Aseem R; Nifong, L Wiley; Chitwood, W Randolph

    2016-02-01

    Atrial septal defect is one of the most common congenital heart anomalies in adults. Patients with partial atrioventricular canal defects, previously known as ostium primum atrial septal defect, usually present at an early age, and only a few reach adulthood without surgical correction. Herein, we describe a young woman who presented with an ostium primum defect and severe symptomatic mitral and tricuspid regurgitation with paroxysmal atrial fibrillation. A complex repair was successfully done through a left atrial approach using robot-assistance. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  20. Clinicopathologic factors identify sporadic mismatch repair-defective colon cancers

    DEFF Research Database (Denmark)

    Halvarsson, Britta; Anderson, Harald; Domanska, Katarina

    2008-01-01

    were linked to MMR status based on immunostaining and BRAF mutation status.MMR defects were identified in 22.7% of the tumors, with 46 classified as sporadic. When the clinical parameters of age, sex, and proximal tumor location were combined with the morphologic features with the highest relative...... and excluded 61.5% of the tumors from MMR testing. This clinicopathologic index thus successfully selects MMR-defective colon cancers. Udgivelsesdato: 2008-Feb...

  1. Cranial CT and MRI in diseases with DNA repair defects

    Energy Technology Data Exchange (ETDEWEB)

    Demaerel, P.; Kendall, B.E.; Kingsley, D. (Dept. of Neuroradiology, Hospital for Sick Children, London (United Kingdom))

    1992-04-01

    The CT and MRI appearances of 5 patients with Cockayne's syndrome, 5 with ataxia telangiectasia and 1 with Fanconi's anaemia are reported. These conditions, together with Bloom's syndrome and xeroderma pigmentosum are regarded as disorders of DNA repair. Characteristic CT and MRI features of Cockayne's syndrome include generalised atrophy, calcification in basal ganglia and dentate nuclei and white matter low density. Neuroradiological findings in the other DNA repair disorders are nonspecific. (orig.).

  2. Nucleotide excision repair of oxidised genomic DNA is not a source of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine.

    Science.gov (United States)

    Evans, Mark D; Mistry, Vilas; Singh, Rajinder; Gackowski, Daniel; Różalski, Rafał; Siomek-Gorecka, Agnieszka; Phillips, David H; Zuo, Jie; Mullenders, Leon; Pines, Alex; Nakabeppu, Yusaku; Sakumi, Kunihiko; Sekiguchi, Mutsuo; Tsuzuki, Teruhisa; Bignami, Margherita; Oliński, Ryszard; Cooke, Marcus S

    2016-10-01

    Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is a widely measured biomarker of oxidative stress. It has been commonly assumed to be a product of DNA repair, and therefore reflective of DNA oxidation. However, the source of urinary 8-oxodGuo is not understood, although potential confounding contributions from cell turnover and diet have been ruled out. Clearly it is critical to understand the precise biological origins of this important biomarker, so that the target molecule that is oxidised can be identified, and the significance of its excretion can be interpreted fully. In the present study we aimed to assess the contributions of nucleotide excision repair (NER), by both the global genome NER (GG-NER) and transcription-coupled NER (TC-NER) pathways, and sanitisation of the dGTP pool (e.g. via the activity of the MTH1 protein), on the production of 8-oxodGuo, using selected genetically-modified mice. In xeroderma pigmentosum A (XPA) mice, in which GG-NER and TC-NER are both defective, the urinary 8-oxodGuo data were unequivocal in ruling out a contribution from NER. In line with the XPA data, the production of urinary 8-oxodGuo was not affected in the xeroderma pigmentosum C mice, specifically excluding a role of the GG-NER pathway. The bulk of the literature supports the mechanism that the NER proteins are responsible for removing damage to the transcribed strand of DNA via TC-NER, and on this basis we also examined Cockayne Syndrome mice, which have a functional loss of TC-NER. These mice showed no difference in urinary 8-oxodGuo excretion, compared to wild type, demonstrating that TC-NER does not contribute to urinary 8-oxodGuo levels. These findings call into question whether genomic DNA is the primary source of urinary 8-oxodGuo, which would largely exclude it as a biomarker of DNA oxidation. The urinary 8-oxodGuo levels from the MTH1 mice (both knock-out and hMTH1-Tg) were not significantly different to the wild-type mice. We suggest that these

  3. Cartilage repair in an osteochondral defect in a rabbit model

    NARCIS (Netherlands)

    Barron, V.; Merghani, K.; Nandakumar, A.; van Blitterswijk, Clemens; Habibovic, Pamela; Shaw, G.; Coleman, C.; Hayes, J.; Moroni, Lorenzo; Barry, F.; Murphy, M.

    2013-01-01

    Despite the fact that mesenchymal stem cells (MSC) offer clinical potential for osteoarthritis applications, retaining sufficient numbers of functional MSC at the site of injury for optimal repair still continues to be a major challenge. One method of overcoming this limitation is to create an

  4. Prevalence and prognostic role of mismatch repair gene defect in endometrial cancer patients.

    Science.gov (United States)

    Tangjitgamol, Siriwan; Kittisiam, Thannaporn; Tanvanich, Sujitra

    2017-09-01

    The study was to evaluate the prevalence of mismatch repair gene defect among Thai patients with endometrial cancer and its association with clinico-pathological features and survivals. The formalin fixed paraffin-embedded blocks of EMC tissue from hysterectomy specimens of patients having surgery in our institution between 1 Jan 1995 and 31 December 2016 were assessed for the immunohistochemical expression of 4 mismatch repair proteins (MLH1, PMS, MSH2, MSH 6). Mismatch repair gene defect was determined by a negative expression of at least 1 protein. Among 385 EMC patients included in the study, mean age was 57.3 ± 10.8 years with 62.3% aged ⩽ 60 years. The most frequent mismatch repair gene defect was MSH6 (38.7%), followed by PMS2 (34.3%), MLH1 (33.2%), and MSH2 (16.4%). Overall, 55.1% showed negative expression of at least one protein. We found significantly higher mismatch repair gene defect in patients aged ⩽ 60 years, with early stage disease, and negative lymph node status than the other comparative groups: 59.2% vs 48.3% for age (p = 0.037), 58.2% vs 45.2% (p = 0.027) for stage, and 58.1% vs 44.6% (p = 0.048) for nodal status. The 5-year progression-free survival, overall survival, and endometrial cancer-specific survival of patients with mismatch repair gene defect was higher than those without gene defect. The differences were statistically significant for only progression-free survival and endometrial cancer-specific survival: 87.7% (95% confidence interval = 83.0%-92.4%) vs 81.5% (95% confidence interval = 75.4%-87.6%) (p = 0.049) for progression-free survival and 91.0% (95% confidence interval = 86.9%-95.1%) vs 85.5% (95% confidence interval = 80.0%-91.0%) (p = 0.044) for endometrial cancer-specific survival, respectively. In conclusion, more than half of Thai endometrial cancer patients had mismatch repair gene defect. The patients with mismatch repair gene defect had significantly younger age (⩽ 60 years) and better prognosis in terms of

  5. Haploinsufficiency for BRCA1 is associated with normal levels of DNA nucleotide excision repair in breast tissue and blood lymphocytes

    Directory of Open Access Journals (Sweden)

    Johnson Jennifer M

    2005-06-01

    Full Text Available Abstract Background Screening mammography has had a positive impact on breast cancer mortality but cannot detect all breast tumors. In a small study, we confirmed that low power magnetic resonance imaging (MRI could identify mammographically undetectable tumors by applying it to a high risk population. Tumors detected by this new technology could have unique etiologies and/or presentations, and may represent an increasing proportion of clinical practice as new screening methods are validated and applied. A very important aspect of this etiology is genomic instability, which is associated with the loss of activity of the breast cancer-predisposing genes BRCA1 and BRCA2. In sporadic breast cancer, however, there is evidence for the involvement of a different pathway of DNA repair, nucleotide excision repair (NER, which remediates lesions that cause a distortion of the DNA helix, including DNA cross-links. Case presentation We describe a breast cancer patient with a mammographically undetectable stage I tumor identified in our MRI screening study. She was originally considered to be at high risk due to the familial occurrence of breast and other types of cancer, and after diagnosis was confirmed as a carrier of a Q1200X mutation in the BRCA1 gene. In vitro analysis of her normal breast tissue showed no differences in growth rate or differentiation potential from disease-free controls. Analysis of cultured blood lymphocyte and breast epithelial cell samples with the unscheduled DNA synthesis (UDS assay revealed no deficiency in NER. Conclusion As new breast cancer screening methods become available and cost effective, patients such as this one will constitute an increasing proportion of the incident population, so it is important to determine whether they differ from current patients in any clinically important ways. Despite her status as a BRCA1 mutation carrier, and her mammographically dense breast tissue, we did not find increased cell

  6. Poly(ADP-ribose) polymerase 1 regulates activity of DNA polymerase {beta} in long patch base excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanova, Maria; Khodyreva, Svetlana [Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk (Russian Federation); Lavrik, Olga, E-mail: lavrik@niboch.nsc.ru [Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk (Russian Federation)

    2010-03-01

    Poly(ADP-ribose)polymerase 1 (PARP1), functioning as DNA nick-sensor, interacts with base excision repair (BER) DNA intermediates containing single-strand breaks. When bound to DNA breaks, PARP1 catalyzes synthesis of poly(ADP-ribose) covalently attached to itself and some nuclear proteins. Autopoly(ADP-ribosyl)ation of PARP1 facilitates its dissociation from DNA breaks and is considered as a factor regulating DNA repair. In the study, using system reconstituted from purified BER proteins, bovine testis nuclear extract and model BER DNA intermediates, we examined the influence of PARP1 and its autopoly(ADP-ribosyl)ation on DNA polymerase {beta} (Pol {beta})-mediated long patch (LP) BER DNA synthesis that is accomplished through a cooperation between Pol {beta} and apurinic/apyrimidinic endonuclease1 (APE1) or flap endonuclease 1 (FEN1) and gap-filling activity of Pol {beta}. PARP1 upon interaction with nicked LP BER DNA intermediated, formed after gap-filling, was shown to suppress the subsequent steps in LP pathway. PARP1 interferes with APE1-dependent stimulation of DNA synthesis by Pol {beta} via strand-displacement mechanism. PARP1 also represses Pol {beta}/FEN1-mediated LP BER DNA synthesis via a 'gap translation' mechanism inhibiting FEN1 activity on the nicked DNA intermediate. Poly(ADP-ribosyl)ation of PARP1 abolishes its inhibitory influence on LP BER DNA synthesis catalyzed by Pol {beta} both via APE1-mediated strand-displacement and FEN1-mediated 'gap translation' mechanism. Thus PARP1 may act as a negative regulator of Pol {beta} activity in LP BER pathway and poly(ADP-ribosyl)ation of PARP1 seems to play a critical role in enablement of Pol {beta}-mediated DNA synthesis in this process. In contrast, interaction of PARP1 with one nucleotide gapped DNA mimicking the intermediate of short patch (SP) BER slightly inhibits the gap-filling activity of Pol {beta} and the overall efficiency of SP BER is practically unaffected by PARP1. Thus

  7. The role of base excision repair in the development of primary open angle glaucoma in the Polish population

    Energy Technology Data Exchange (ETDEWEB)

    Cuchra, Magda; Markiewicz, Lukasz; Mucha, Bartosz [Department of Clinical Chemistry and Biochemistry, Medical University of Lodz (Poland); Pytel, Dariusz [The Abramson Family Cancer Research Institute, Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425 (United States); Szymanek, Katarzyna [Department of Ophthalmology, Medical University of Warsaw, SPKSO Hospital, Warsaw (Poland); Szemraj, Janusz [Department of Medical Biochemistry, Medical University of Lodz, Lodz (Poland); Szaflik, Jerzy; Szaflik, Jacek P. [Department of Ophthalmology, Medical University of Warsaw, SPKSO Hospital, Warsaw (Poland); Majsterek, Ireneusz, E-mail: ireneusz.majsterek@umed.lodz.pl [Department of Clinical Chemistry and Biochemistry, Medical University of Lodz (Poland)

    2015-08-15

    Highlights: • We suggested the association of XRCC1 gene with the increase risk of POAG development. • We indicated the association of clinical factor and XRCC1, MUTYH, ADPRT and APE1 genes with POAG progression. • We postulated the increase level of oxidative DNA damage in group of patients with POAG in relation to healthy controls. • We suggested the slightly decrease ability to repair of oxidative DNA damage. • This is the first data that showed the role of BER mechanism in POAG pathogenesis. - Abstract: Glaucoma is a leading cause of irreversible blindness in developing countries. Previous data have shown that progressive loss of human TM cells may be connected with chronic exposure to oxidative stress. This hypothesis may suggest a role of the base excision repair (BER) pathway of oxidative DNA damage in primary open angle glaucoma (POAG) patients. The aim of our study was to evaluate an association of BER gene polymorphism with a risk of POAG. Moreover, an association of clinical parameters was examined including cup disk ratio (c/d), rim area (RA) and retinal nerve fiber layer (RNFL) with glaucoma progression according to BER gene polymorphisms. Our research included 412 patients with POAG and 454 healthy controls. Gene polymorphisms were analyzed by PCR-RFLP. Heidelberg Retinal Tomography (HRT) clinical parameters were also analyzed. The 399Arg/Gln genotype of the XRCC1 gene (OR 1.38; 95% CI 1.02–1.89 p = 0.03) was associated with an increased risk of POAG occurrence. It was indicated that the 399Gln/Gln XRCC1 genotype might increase the risk of POAG progression according to the c/d ratio (OR 1.67; 95% CI 1.07–2.61 P = 0.02) clinical parameter. Moreover, the association of VF factor with 148Asp/Glu of APE1 genotype distribution and POAG progression (OR 2.25; 95% CI 1.30–3.89) was also found. Additionally, the analysis of the 324Gln/His MUTYH polymorphism gene distribution in the patient group according to RNFL factor showed that it might

  8. Epidermal Growth Factor Receptor, Excision-Repair Cross-Complementation Group 1 Protein, and Thymidylate Synthase Expression in Penile Cancer.

    Science.gov (United States)

    Dorff, Tanya B; Schuckman, Anne K; Schwartz, Rachel; Rashad, Sadaf; Bulbul, Ajaz; Cai, Jie; Pinski, Jacek; Ma, Yanling; Danenberg, Kathleen; Skinner, Eila; Quinn, David I

    2016-10-01

    To describe the expression of tissue epidermal growth factor receptor (EGFR), excision-repair cross-complementation group 1 protein (ERCC1), and thymidylate synthase (TS) in patients with penile cancer and explore their association with stage and outcome. A total of 52 patients with penile squamous cell cancer who were treated at the University of Southern California from 1995 to 2010 were identified. Paraffin-embedded tissue underwent mRNA quantitation and immunohistochemistry for expression of EGFR, ERCC1, and TS. KRAS mutations were evaluated using polymerase chain reaction-based sequencing. EGFR overexpression was common by mRNA (median, 5.09; range, 1.92-104.5) and immunohistochemistry. EGFR expression > 7 was associated with advanced stage and poor differentiation (P = .01 and .034 respectively) but not with survival in multivariate analysis. ERCC1 mRNA expression was a median of 0.65 (range, 0.21-1.87). TS expression was a median of 1.88 (range, 0.54-6.47). ERCC1 and TS expression were not associated with grade, stage, or survival. There were no KRAS mutations identified. A total of 17 men received chemotherapy; 8 (47%) had an objective response, including 1 with a pathologic complete response. There was a trend for lower expression of EGFR corresponding to a higher likelihood of response (response rate [RR]) to chemotherapy: 67% RR in EGFR mRNA  7 (P = .31). High expression of EGFR mRNA in squamous cell carcinoma of the penis is associated with advanced stage and poor differentiation, but not survival. In our small heterogeneous subset, molecular marker expression did not show a correlation with the likelihood of chemotherapy response. A prospective evaluation of the role of the EGFR pathway and its regulatory environment in penile cancer is warranted. Given the rarity of this cancer, collaborative prospective cohort evaluations and trials need to be encouraged. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Anatomic biventricular repair in right isomerism with noncommitted ventricular septal defect.

    Science.gov (United States)

    Katewa, Ashish; Marwah, Ashutosh; Singh, Vishal; Ramaswamy, Arun; Sharma, Rajesh

    2012-07-01

    Biventricular repair in right atrial isomerism is rarely feasible due to associated anomalies of venous connection, ventricular imbalance, nonroutabilty of the interventricular communication, a common atrioventricular junction, and inadequate pulmonary arterial branches. These patients are also often not ideal for univentricular repair due to some of the above associations. We describe a novel surgical technique that was utilized in such a patient for biventricular repair of a child with right atrial isomerism with total anomalous pulmonary venous connection, regurgitant common atrioventricular valve, hypoplastic left ventricle, nonroutable ventricular septal defect, and pulmonary stenosis.

  10. Total endoscopic robotic atrial septal defect repair in a patient with dextrocardia and situs inversus totalis

    Science.gov (United States)

    Iino, Kenji; Watanabe, Go; Ishikawa, Norihiko; Tomita, Shigeyuki

    2012-01-01

    Situs inversus with mirror-image of the heart is a rare condition. The present report describes a case of a patient with dextrocardia with situs inversus who had atrial septal defect with multiple holes in the fossa ovalis. The patient underwent total endoscopic atrial septal defect repair using the da Vinci surgical system. This procedure was achieved safely with good clinical and excellent cosmetic results. PMID:22200951

  11. Biomechanical Evaluation of Spontaneity Repair of Osteochondral Defects in Rabbit Knee

    Directory of Open Access Journals (Sweden)

    Fahimeh Kamali

    2007-01-01

    Full Text Available Objective: Full-thickness defects measuring 3 mm in diameter have been commonly used in studies of rabbits to evaluate new procedures designed to improve the quality of articular cartilage repair. These defects initially heal spontaneously. However, little information is available on the characteristics of repair of large defects. The aim of present study was to define the biomechanical characteristics of repair of 5x4 mm full- thickness osteochondral defects in the adolescent male rabbit. Materials & Methods: In a Quasi - Experimental study 5 millimeter diameter and 4 mm deep osteochondral defects were drilled in femoral patellar groove of twenty-one rabbits , and examined at 4 ,8 and 16 weeks. The left knee was kept intact as the normal control. . The knee joints were removed, and both legs were examined biomechanically by in situ indentation method at three time- intervals (4, 8, 16 weeks. The instantaneous and equilibrium elastic- modulus (after 900 second measured during the test. Results: There were no differences in cartilage mechanical properties (instantaneous and equilibrium elastic- modulus between weeks (4, 8, 16 weeks in two groups (P>0/05. Although Significant differences between experimental and control groups were seen in 16 weeks in instantaneous elastic- modulus (P<0/05. New tissue supported high stiffness than normal control in 16 weeks. Conclusion: Full-thickness osteochondral defects, measuring 5x4 mm in diameter and dept in patellar groove of adolescent rabbit knee heal spontaneously.

  12. Angiogenic peptide nanofibers repair cardiac tissue defect after myocardial infarction.

    Science.gov (United States)

    Rufaihah, Abdul Jalil; Yasa, I Ceren; Ramanujam, Vaibavi Srirangam; Arularasu, Suganya Cheyyatraivendran; Kofidis, Theo; Guler, Mustafa O; Tekinay, Ayse B

    2017-08-01

    Myocardial infarction remains one of the top leading causes of death in the world and the damage sustained in the heart eventually develops into heart failure. Limited conventional treatment options due to the inability of the myocardium to regenerate after injury and shortage of organ donors require the development of alternative therapies to repair the damaged myocardium. Current efforts in repairing damage after myocardial infarction concentrates on using biologically derived molecules such as growth factors or stem cells, which carry risks of serious side effects including the formation of teratomas. Here, we demonstrate that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization in cardiovascular tissue after myocardial infarction, without the addition of any biologically derived factors or stem cells. When the GAG mimetic nanofiber gels were injected in the infarct site of rodent myocardial infarct model, increased VEGF-A expression and recruitment of vascular cells was observed. This was accompanied with significant degree of neovascularization and better cardiac performance when compared to the control saline group. The results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair. We present a synthetic bioactive peptide nanofiber system can enhance cardiac function and enhance cardiovascular regeneration after myocardial infarction (MI) without the addition of growth factors, stem cells or other biologically derived molecules. Current state of the art in cardiac repair after MI utilize at least one of the above mentioned biologically derived molecules, thus our approach is ground-breaking for cardiovascular therapy after MI. In this work, we showed that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization and cardiomyocyte differentiation for the regeneration of cardiovascular

  13. Repair of Head and Face Defects with the Use of Pericranial Flap

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    Mohammad Naeimi

    2011-01-01

    Full Text Available Introduction: The pericranial flaps' benefits have been described in many otolaryngologic, maxillofacial and plastic surgery literature. The benefits ar e due to the pericranial flaps unique characteristics including good flexibility and mobility, very rich blood supply from several arterial sources and access to sufficient bulk of the flap without any need for distant surgical sites. Using pericranial flaps to repair the local defects of the head and face region in several cases has been reported in this study. Materials and Methods: A follow up study was carried out on 12 patients who had undergone frontal sinus obliteration; auriculoplasty and repair of the orbital walls and scalp’s defects. Pericranial flap had been used for all these patients. Demographic specifications, surgical indications, imaging evaluations and early and late complications were recorded as well. The functional and cosmetic results and also the satisfaction level of patients were also assessed. Results: According to the average follow up period which lasted about 4 years, none of the patients suffered early or late significant complications. No disease relapse or need for revision surgery was reported. Almost all patients were completely satisfied with the procedure and its cosmetic results. Conclusion: The use of a pericranial flap is a simple, quick, cost-effective and safe method for repair of head and face defects. Although, a longer follow up time is required, but this uncomplicated method has been considered as an ideal method to repair sinonasal, ear and scalp defects.

  14. Catheter ablation of atrial tachycardia after interatrial defect repair with patch apposition.

    Science.gov (United States)

    Nguyen, B L; Garante, C M; Tersigni, F; Sergiacomi, R; Petrassi, M; Di Matteo, A; Tufano, F; Alessandri, N

    2012-02-01

    A 54-year-old woman with history of septal atrial mixoma surgically treated and drug-refractory supraventricular tachyarrhythmia underwent catheter ablation of macro-reentry areas near the pericardial patch placed to repair an interatrial defect. The use of ablative therapy has been successful to cure this arrhythmia.

  15. Successful three stage repair of a large congenital abdominal region defect

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    Vaidehi Agrawal

    2015-06-01

    Full Text Available We present two infants born with large, right upper quadrant defects which cannot be categorized as either a gastroschisis or omphalocele. We successfully managed one infant with a three stage repair using polytetrafluoroethylene (PTFE patch, porcine urinary bladder matrix (UBM and delayed surgical closure. The second infant passed away due to parental consent care withdrawal.

  16. Repair of Posterior Infarct Ventricular Septal Defect in a Patient with Dextrocardia and Situs Inversus.

    Science.gov (United States)

    Nesta, Marialisa; Mazza, Andrea; Perri, Gianluigi; Bruno, Piergiorgio; Massetti, Massimo

    2016-03-01

    We report a patient with situs inversus who developed a large posterior interventricular septum pseudoaneurysm with a septal defect following a myocardial infarction. The ventricular septum was approached through the left ventricle and the entrance of the pseudoaneurysm was repaired with a strip of equine pericardium. © 2016 Wiley Periodicals, Inc.

  17. Repair of a mandibular defect with a free vascularized coccygeal vertebra transfer in a dog.

    Science.gov (United States)

    Yeh, L S; Hou, S M

    1994-01-01

    Bilateral mandibular defects in a male mongrel dog were repaired. On the left side, a free vascularized coccygeal bone graft that included the median caudal artery and caudal vein was used to correct the defect. On the right side, the defect was bridged with a bone plate and screws. For further immobilization, the muzzle was temporarily taped for 3 weeks and a pharyngostomy tube was used for nutritional support. The dog was able to eat dry commercial food satisfactorily within 2 months of surgery despite mild malocclusion. Radiographs taken 2 months and 18 months postoperatively showed bony union with graft hypertrophy in the left mandible, whereas the right mandibular defect showed protracted nonunion. The results indicate that vascularized coccygeal vertebra transfer provides an alternative for the management of canine mandibular defects.

  18. Closure of Myelomeningocele Defects Using a Limberg Flap or Direct Repair

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    Jung-Hwan Shim

    2016-01-01

    Full Text Available BackgroundThe global prevalence of myelomeningocele has been reported to be 0.8–1 per 1,000 live births. Early closure of the defect is considered to be the standard of care. Various surgical methods have been reported, such as primary skin closure, local skin flaps, musculocutaneous flaps, and skin grafts. The aim of this study was to describe the clinical characteristics of myelomeningocele defects and present the surgical outcomes of recent cases of myelomeningocele at our institution.MethodsPatients who underwent surgical closure of myelomeningocele at our institution from January 2004 to December 2013 were included in this study. A retrospective chart review of their medical records was performed, and comorbidities, defect size, location, surgical procedures, complications, and the final results were analyzed.ResultsA total of 14 patients underwent surgical closure for myelomeningocele defects. Twelve cases were closed with direct skin repair, while two cases required local skin flaps to cover the skin defects. Three cases of infection occurred, requiring incision and either drainage or removal of allogenic materials. One case of partial flap necrosis occurred, requiring secondary revision using a rotational flap and a full-thickness skin graft. Despite these complications, all wounds eventually healed completely.ConclusionsMost myelomeningocele defects can be managed by direct skin repair alone. In cases of large defects, in which direct repair is not possible, local flaps may be used to cover the defect. Complications such as wound dehiscence and partial flap necrosis occurred in this study; however, all such complications were successfully managed with simple ancillary procedures.

  19. An experimental study on the application of radionuclide imaging in repair of the bone defect

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    Weimin Zhu

    2011-08-01

    Full Text Available The aim of our study was to validate the effect of radionuclide imaging in early monitoring of the bone’s reconstruction, the animal model of bone defect was made on the rabbits repaired with HA artificial bone. The ability of bone defect repair was evaluated by using radionuclide bone imaging at 2, 4, 8 and 12 weeks postoperatively. The results indicate that the experimental group stimulated more bone formation than that of the control group. The differences of the bone reconstruction ability were statistically significant (p<0.05. The nano-HA artificial has good bone conduction, and it can be used for the treatment of bone defects. Radionuclide imaging may be an effective and first choice method for the early monitoring of the bone’s reconstruction.

  20. Twelve-year experience with expanded polytetrafluoroethylene in the repair of abdominal wall defects.

    Science.gov (United States)

    Bauer, J J; Harris, M T; Kreel, I; Gelernt, I M

    1999-01-01

    A prosthetic device must be used to repair ventral hernias in patients with insufficient tissue for a tension-free primary closure. Several prosthetic materials have been employed for this purpose, with varying results. We here review a long experience with the use of expanded polytetrafluoroethylene (ePTFE) patches in the open repair of large abdominal wall defects. Demographic, operative, follow-up, and histologic data were recorded and analyzed for all patients in a surgical practice who were treated for large abdominal wall defects with open repair using ePTFE patches between November 1983 and March 1996. Ventral hernia repairs using an ePTFE patch were performed in 98 patients. In 48 (49%), the patient had already undergone at least one previous ventral hernia repair. Of the 98 operations, 78 were full-thickness repairs, 11 were Rives-Stoppa procedures, and 9 were onlay operations. Complications included 5 seromas, 3 fistulas related to removal of a previously implanted prosthesis, and 9 infections. In addition, 10 patients developed recurrent hernias not related to explantation of the patch because of infection or fistula. In 3 patients, infections were treated successfully without removal of the patch. There were no complications related to adhesions, erosion of the patch into the viscera, or bowel obstruction. Histologic studies of longterm ePTFE implants showed excellent fibrous tissue ingrowth and minimal foreign body response. Our long-term clinical experience indicates that prosthetic patches of ePTFE are safe and effective when used in the repair of large abdominal wall defects that cannot be closed primarily. Operative complications were within acceptable limits, as was the reherniation rate.

  1. Distant neighbor base sequence context effects in human nucleotide excision repair of a benzo[a]pyrene-derived DNA lesion.

    Science.gov (United States)

    Cai, Yuqin; Kropachev, Konstantin; Xu, Rong; Tang, Yijin; Kolbanovskii, Marina; Kolbanovskii, Alexander; Amin, Shantu; Patel, Dinshaw J; Broyde, Suse; Geacintov, Nicholas E

    2010-06-11

    The effects of non-nearest base sequences, beyond the nucleotides flanking a DNA lesion on either side, on nucleotide excision repair (NER) in extracts from human cells were investigated. We constructed two duplexes containing the same minor groove-aligned 10S (+)-trans-anti-B[a]P-N(2)-dG (G*) DNA adduct, derived from the environmental carcinogen benzo[a]pyrene (B[a]P): 5'-C-C-A-T-C-G*-C-T-A-C-C-3' (CG*C-I), and 5'-C-A-C3-A4-C5-G*-C-A-C-A-C-3' (CG*C-II). We used polyacrylamide gel electrophoresis to compare the extent of DNA bending, and molecular dynamics simulations to analyze the structural characteristics of these two DNA duplexes. The NER efficiencies are 1.6(+/-0.2)-fold greater in the case of the CG*C-II than the CG*C-I sequence context in 135-mer duplexes. Gel electrophoresis and self-ligation circularization experiments revealed that the CG*C-II duplex is more bent than the CG*C-I duplex, while molecular dynamics simulations showed that the unique -C3-A4-C5- segment in the CG*C-II duplex plays a key role. The presence of a minor groove-positioned guanine amino group, the Watson-Crick partner to C3, acts as a wedge; facilitated by a highly deformable local -C3-A4- base step, this amino group allows the B[a]P ring system to produce a more enlarged minor groove in CG*C-II than in CG*C-I, as well as a local untwisting and enlarged and flexible Roll only in the CG*C-II sequence. These structural properties fit well with our earlier findings that in the case of the family of minor groove 10S (+)-trans-anti-B[a]P-N(2)-dG lesions, flexible bends and enlarged minor groove widths constitute NER recognition signals, and extend our understanding of sequence context effects on NER to the neighbors that are distant to the lesion. Copyright 2010 Elsevier Ltd. All rights reserved.

  2. Recognition of Damaged DNA for Nucleotide Excision Repair: A Correlated Motion Mechanism with a Mismatched cis-syn Thymine Dimer Lesion.

    Science.gov (United States)

    Mu, Hong; Geacintov, Nicholas E; Zhang, Yingkai; Broyde, Suse

    2015-09-01

    Mammalian global genomic nucleotide excision repair requires lesion recognition by XPC, whose detailed binding mechanism remains to be elucidated. Here we have delineated the dynamic molecular pathway and energetics of lesion-specific and productive binding by the Rad4/yeast XPC lesion recognition factor, as it forms the open complex [Min, J. H., and Pavletich, N. P. (2007) Nature 449, 570-575; Chen, X., et al. (2015) Nat. Commun. 6, 5849] that is required for excision. We investigated extensively a cis-syn cyclobutane pyrimidine dimer in mismatched duplex DNA, using high-level computational approaches. Our results delineate a preferred correlated motion mechanism, which provides for the first time an atomistic description of the sequence of events as Rad4 productively binds to the damaged DNA.

  3. Repair of articular osteochondral defects of the knee joint using a composite lamellar scaffold.

    Science.gov (United States)

    Lv, Y M; Yu, Q S

    2015-04-01

    The major problem with repair of an articular cartilage injury is the extensive difference in the structure and function of regenerated, compared with normal cartilage. Our work investigates the feasibility of repairing articular osteochondral defects in the canine knee joint using a composite lamellar scaffold of nano-ß-tricalcium phosphate (ß-TCP)/collagen (col) I and II with bone marrow stromal stem cells (BMSCs) and assesses its biological compatibility. The bone-cartilage scaffold was prepared as a laminated composite, using hydroxyapatite nanoparticles (nano-HAP)/collagen I/copolymer of polylactic acid-hydroxyacetic acid as the bony scaffold, and sodium hyaluronate/poly(lactic-co-glycolic acid) as the cartilaginous scaffold. Ten-to 12-month-old hybrid canines were randomly divided into an experimental group and a control group. BMSCs were obtained from the iliac crest of each animal, and only those of the third generation were used in experiments. An articular osteochondral defect was created in the right knee of dogs in both groups. Those in the experimental group were treated by implanting the composites consisting of the lamellar scaffold of ß-TCP/col I/col II/BMSCs. Those in the control group were left untreated. After 12 weeks of implantation, defects in the experimental group were filled with white semi-translucent tissue, protruding slightly over the peripheral cartilage surface. After 24 weeks, the defect space in the experimental group was filled with new cartilage tissues, finely integrated into surrounding normal cartilage. The lamellar scaffold of ß-TCP/col I/col II was gradually degraded and absorbed, while new cartilage tissue formed. In the control group, the defects were not repaired. This method can be used as a suitable scaffold material for the tissue-engineered repair of articular cartilage defects. Cite this article: Bone Joint Res 2015;4:56-64. ©2015 The British Editorial Society of Bone & Joint Surgery.

  4. Mesenchymal cell-based repair of large, full-thickness defects of articular cartilage.

    Science.gov (United States)

    Wakitani, S; Goto, T; Pineda, S J; Young, R G; Mansour, J M; Caplan, A I; Goldberg, V M

    1994-04-01

    Osteochondral progenitor cells were used to repair large, full-thickness defects of the articular cartilage that had been created in the knees of rabbits. Adherent cells from bone marrow, or cells from the periosteum that had been liberated from connective tissue by collagenase digestion, were grown in culture, dispersed in a type-I collagen gel, and transplanted into a large (three-by-six-millimeter), full-thickness (three-millimeter) defect in the weight-bearing surface of the medial femoral condyle. The contralateral knee served as a control: either the defect in that knee was left empty or a cell-free collagen gel was implanted. The periosteal and the bone-marrow-derived cells showed similar patterns of differentiation into articular cartilage and subchondral bone. Specimens of reparative tissue were analyzed with use of a semiquantitative histological grading system and by mechanical testing with employment of a porous indenter to measure the compliance of the tissue at intervals until twenty-four weeks after the operation. There was no apparent difference between the results obtained with the cells from the bone marrow and those from the periosteum. As early as two weeks after transplantation, the autologous osteochondral progenitor cells had uniformly differentiated into chondrocytes throughout the defects. This repair cartilage was subsequently replaced with bone in a proximal-to-distal direction, until, at twenty-four weeks after transplantation, the subchondral bone was completely repaired, without loss of overlying articular cartilage. The mechanical testing data were a useful index of the quality of the long-term repair. Twenty-four weeks after transplantation, the reparative tissue of both the bone-marrow and the periosteal cells was stiffer and less compliant than the tissue derived from the empty defects but less stiff and more compliant than normal cartilage. The current modalities for the repair of defects of the articular cartilage have many

  5. * Hypoxia Biomimicry to Enhance Monetite Bone Defect Repair.

    Science.gov (United States)

    Drager, Justin; Ramirez-GarciaLuna, Jose Luis; Kumar, Abhishek; Gbureck, Uwe; Harvey, Edward J; Barralet, Jake E

    2017-12-01

    Tissue hypoxia is a critical driving force for angiogenic and osteogenic responses in bone regeneration and is, at least partly, under the control of the Hypoxia Inducible Factor-1α (HIF-1α) pathway. Recently, the widely used iron chelator deferoxamine (DFO) has been found to elevate HIF-1α levels independent of oxygen concentrations, thereby, creating an otherwise normal environment that mimics the hypoxic state. This has the potential to augment the biological properties of inorganic scaffolds without the need of recombinant growth factors. This pilot study investigates the effect of local delivery of DFO on bone formation and osseointegration of an anatomically matched bone graft substitute, in the treatment of segmental bone defects. Three-dimensional printing was used to create monetite grafts, which were implanted into 10 mm midshaft ulnar defects in eight rabbits. Starting postoperative day 4, one graft site in each animal was injected with 600 μL (200 μM) of DFO every 48 h for six doses. Saline was injected in the contralateral limb as a control. At 8 weeks, micro-CT and histology were used to determine new bone growth, vascularity, and assess osseointegration. Six animals completed the protocol. Bone metric analysis using micro-CT showed a significantly greater amount of new bone formed (19.5% vs. 13.65% p = 0.042) and an increase in bone-implant contact area (63.1 mm2 vs. 33.2 mm2 p = 0.03) in the DFO group compared with control. Vascular channel volume was significantly greater in the DFO group (20.9% vs. 16.2% p = 0.004). Histology showed increased bone formation within the osteotomy gap, more bone integrated with the graft surface as well as more matured soft tissue callus in the DFO group. This study demonstrates a significant increase in new bone formation after delivery of DFO in a rabbit long bone defect bridged by a 3D-printed bioresorbable bone graft substitute. Given the safety, ease of handling, and low expense of

  6. Transient expression of a plasmid gene, a tool to study DNA repair in human cells: defect of DNA repair in Cockayne syndrome; one thymine cyclobutane dimer is sufficient to block transcription.

    Science.gov (United States)

    Klocker, H; Schneider, R; Burtscher, H J; Auer, B; Hirsch-Kauffmann, M; Schweiger, M

    1986-01-01

    Transfected recombinant DNA with regulatory elements such as eukaryotic promoter and termination sites is transiently expressed in human fibroblast cells. Utilizing an expression vector containing the simian virus 40 (SV 40) early control region followed by the E. coli chloramphenicol acetyltransferase (CAT) gene, we investigated the ability of normal, Xeroderma pigmentosum and Cockayne Syndrome cells to repair UV lesions in transfected DNA. Fibroblasts from Xeroderma pigmentosum patients which cannot excise pyrimidine cyclobutane dimers were unable to restore expression of UV irradiated CAT gene. An UV dose inducing one thymine cyclobutane dimer in the transcribed strand of the CAT gene blocked its transcription in these repair deficient cells. Normal cell were able to repair the lesions in transfected DNA during an incubation period of about 40 h and in this way could overcome the UV block. In several fibroblast cell lines from patients suffering from Cockayne Syndrome expression of UV damaged CAT gene was restored significantly less than in normal fibroblasts, indicating that Cockayne Syndrome is associated with a UV repair defect.

  7. [CLINICAL APPLICATION OF LATERAL ARM LOBULATED FLAPS TO REPAIR MULTIPLE SOFT TISSUE DEFECT OF HAND].

    Science.gov (United States)

    Ye, Shuming; Teng, Xiaofeng; Chen, Hong; Jing, Juehua; Zhang, Jisen

    2016-04-01

    To explore the effectiveness and operation of repairing multiple soft tissue defects in hands with lateral arm lobulated flaps. Between October 2013 and September 2015, 13 cases of multiple soft tissue defects in the hand with tendon or bone exposure were treated with lateral arm lobulated flaps. All patients were males with average age of 28 years (range, 23-45 years). Defects were caused by penetrating injury in 7 cases, traffic accident injury in 3 cases, and hot-crush injury in 3 cases. Six patients had skin defect of the left 2 fingers after opening finger amputation, and 7 patients had skin defect of the palm and the back after hand injury. The size of skin defects ranged from 6 cm x 5 cm to 9 cm x 6 cm. All patients underwent emergency debridement and two-stage repair; the duration from injury to operation was 5-9 days (mean, 7 days). The size of flap was 6 cm x 5 cm-9 cm x 6 cm. All flaps survived completely, with no vascular crisis. Primary healing was obtained at donor and recipient sites, and the grafted skin survived. All cases were followed up 3-24 months (mean, 12 months). The appearance and texture of the flaps were similar to those of adjacent skin. Bulky flap was observed in 4 cases, and second stage operation was performed to make the flap thinner at 3 months after operation. The sensation of flap reached S₃-S₄. The lateral arm lobulated flap based on the radial collateral artery has constant vascular anatomy, easy-to-harvest, and large rotation angle. It is an effective procedure to repair small and medium size skin defects of the hand with satisfied texture and sensory recovery.

  8. [Repair of defects in lower extremities with peroneal perforator-based sural neurofasciocutaneous flaps].

    Science.gov (United States)

    Wang, Xian-cheng; Li, Xiao-fang; Fang, Bai-rong; Lu, Qing; Yang, Li-chang; Sun, Yang; A, Mi-te; Gao, Yuan; Tang, Liang; He, Ji-yong; Wang, Yu-yin

    2013-10-01

    To explore the operative technique and clinical results of using peroneal perforator-based sural neurofasciocutaneous flaps to repair skin and soft tissue defects in lower extremities. From January 2009 to March 2012, 26 patients with skin and soft tissue defects at distal region of leg and foot were hospitalized. Among them, 9 patients suffered from tendon or bone exposure at the distal region of leg after injury due to traffic accident; 4 patients suffered from skin defects in the ankle as a result of electric injury; 8 patients suffered from chronic ulcer at the distal part of leg and foot; 5 patients suffered from plantar pressure ulcer. After debridement, soft tissue defect sizes ranged from 11 cm×5 cm to 18 cm×13 cm. According to the position and size of the defects, peroneal perforator-based sural neurofasciocutaneous flaps were designed and procured to repair the skin and soft tissue defects. The size of flaps ranged from 12 cm×6 cm to 20 cm×15 cm. Flap donor sites were closed by direct suture or skin grafting. Twenty-five flaps survived completely. Only one flap suffered partial margin necrosis in the size of 2 cm×1 cm, which was healed after dressing change. Patients were followed up for 6 to 12 months. The appearance and sensation of flaps were satisfactory; no ulcer occurred; the movement of lower extremities was normal. It is suitable to repair the skin and soft tissue defects at distal region of leg and foot with the peroneal perforator-based sural neurofasciocutaneous flap, as it possesses reliable blood supply, long and non-bulky pedicle, and sufficient available size. The operation is also easy to perform.

  9. Repair of periprosthetic pelvis defects with porous metal implants: a finite element study.

    Science.gov (United States)

    Levine, Danny L; Dharia, Mehul A; Siggelkow, Eik; Crowninshield, Roy D; Degroff, Dale A; Wentz, Douglas H

    2010-02-01

    Periacetabular osteolysis is a potentially difficult surgical challenge, which can often drive the choice of reconstruction methods used in revision hip replacement. For smaller defects, impaction of bone grafts may be sufficient, but larger defects can require filler materials that provide structural support in addition to filling a void. This study utilized finite element analysis (FEA) to examine the state of stress in periprosthetic pelvic bone when subjected to a stair-climbing load and in the presence of two simulated defects, to show the effect of implanting a defect repair implant fabricated from Trabecular Metal. Even a small medial bone defect showed a local stress elevation of 4x compared with that seen with an acetabular implant supported by intact periacetabular bone. Local bone stress was much greater (8x the baseline level) for a defect case in which the loss of bone superior to the acetabular implant permitted significant migration. FEA results showed that a repair of the small defect with a Trabecular Metal restrictor lowered periprosthetic bone stress to a level comparable to that in the case of a primary implant. For the larger defect case, the use of a Trabecular Metal augment provides structural stabilization and helps to restore the THR head center. However, stress in the adjacent periprosthetic bone is lower than that observed in the defect-free acetabulum. In the augment case, the load path between the femoral head and the pelvis now passes through the augment as the superior rim of the acetabulum has been replaced. Contact-induced stress in the augment is similar in magnitude to that seen in the superior rim of the baseline case, although the stress pattern in the augment is noticeably different from that in intact bone.

  10. Postablative reconstruction of vulvar defects with local fasciocutaneous flaps and superficial fascial system repair.

    Science.gov (United States)

    Al-Benna, Sammy; Tzakas, Elias

    2012-08-01

    Postablative reconstruction of vulvar defects is a difficult challenge because of the functional, locational and cosmetic importance of this region. Local flaps carry a high incidence of delayed wound healing as local flaps may redistribute but not eliminate local wound tension. Repair of the superficial fascial system may avert local complications by minimising tension to the skin and increasing the initial biomechanical strength of wound. The aim of this study was to determine the clinical outcome of local fasciocutaneous flaps used for postablative reconstruction of vulvar defects in which the superficial fascial system was repaired. A retrospective analysis was conducted of patients with vulvar carcinoma in situ or vulvar carcinoma, who underwent ablation and immediate reconstruction with local fasciocutaneous flaps and superficial fascial system repair. Postoperative complications were recorded and clinical outcomes were evaluated. Twelve of the 13 flaps healed primarily. Complications included 2 superficial wound infections, both of which were treated successfully with antibiotic therapy. One flap was complicated by minor wound dehiscence, which healed with conservative treatment. Local fasciocutaneous flaps with superficial fascial system repair provide excellent design flexibility and can be designed and tailored to reconstruct postablative vulvar defects with good outcomes and minimal morbidity.

  11. Sensitivity of excision repair in normal human, xeroderma pigmentosum variant and Cockayne's syndrome fibroblasts to inhibition by cytosine arabinoside

    Energy Technology Data Exchange (ETDEWEB)

    Cleaver, J.E.

    1981-08-01

    Inhibition of the gap-filling, polymerizing step of excision repair by 1-..beta..-D-arabinofuranosylcytosine (ara-C) after irradiation with ultraviolet light in human diploid fibroblasts resulted in the formation of persistent DNA strand breaks in G/sub 1/, G/sub 2/, and plateau phase cells, but not in S phase cells. Addition of hydroxyurea to ara-C resulted in partial inhibition of repair in S phase cells. These observations can be explained either in terms of changing roles in repair for different DNA polymerases throughout the cell cycle or by the presence of a pool of deoxycytidine nucleotides during S phase equivalent to an external source of deoxycytidine at 50 ..mu..M concentration. A similar concentration dependence on ara-C was observed for inhibition of repair in normal human, xeroderma pigmentosum (XP) variant, and Cockayne's syndrome cells. Ara-C produced a similar number of breaks in normal and Cockayne's syndrome cells. Ara-C produced a similar number of breaks in normal and Cockayne's syndrome cells but slightly more in XP variant cells. Exonuclease III and S1 nuclease independently both degraded about 50% of the /sup 3/H-thymidine incorporated into repaired regions in the presence of ara-C. Sequential digestion with both enzymes degraded nearly 90% of the repaired regions. These observations can be explained if excision repair proceeds by displacing the damaged strand so that both the /sup 3/H-labeled patch and the damaged region are still ligated to high molecular weight DNA and compete for the same complementary strand during in vitro incubation with the nucleases. The amount of /sup 3/H-thymidine incorporated in DNA by repair decreased with increasing concentrations of ara-C and hydroxyurea, suggesting that the incomplete patches became shorter under these conditions. Extrapolation of the digestion kinetics with exonuclease III permits an estimate of the normal patch size of about 100 nucleotides, consistent with previous estimates.

  12. Evaluation of a new composite prosthesis for the repair of abdominal wall defects.

    Science.gov (United States)

    Losi, Paola; Munaò, Antonella; Spiller, Dario; Briganti, Enrica; Martinelli, Ilaria; Scoccianti, Marco; Soldani, Giorgio

    2007-10-01

    The degree of integration of biomaterials used in the repair of abdominal wall defects seems to depend upon the structure of the prosthesis. The present investigation evaluates the behaviour in terms of adhesion formation and integration of a new composite prosthesis that could be employed in this clinical application. Full-thickness abdominal wall defects (7 x 5 cm) were created in 16 anaesthetized New Zealand white rabbits and the prosthesis were placed in direct contact with the visceral peritoneum during the experiment. The defects were repaired with a composite prosthesis or pure polypropylene mesh to establish two study groups (n = 8 each). The composite device was constituted by a polypropylene mesh physically attached to a poly(ether)urethane-polydimethylsiloxane laminar sheet. Animals were sacrificed 7, 14, 21 and 30 days after implant and prosthesis/surrounding tissue specimens subjected to light and electron microscopy. Firm adhesions were detected in the polypropylene implants, while they were not present in the composite implants. The excellent behaviour of the composite prosthesis shown in this study warrants further investigation on its use for the repair of abdominal wall defects when a prosthetic device needs to be placed in contact with the intestinal loops.

  13. Tri-layered composite plug for the repair of osteochondral defects: in vivo study in sheep

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    Altug Yucekul

    2017-04-01

    Full Text Available Cartilage defects are a source of pain, immobility, and reduced quality of life for patients who have acquired these defects through injury, wear, or disease. The avascular nature of cartilage tissue adds to the complexity of cartilage tissue repair or regeneration efforts. The known limitations of using autografts, allografts, or xenografts further add to this complexity. Autologous chondrocyte implantation or matrix-assisted chondrocyte implantation techniques attempt to introduce cultured cartilage cells to defect areas in the patient, but clinical success with these are impeded by the avascularity of cartilage tissue. Biodegradable, synthetic scaffolds capable of supporting local cells and overcoming the issue of poor vascularization would bypass the issues of current cartilage treatment options. In this study, we propose a biodegradable, tri-layered (poly(glycolic acid mesh/poly(l-lactic acid-colorant tidemark layer/collagen Type I and ceramic microparticle-coated poly(l-lactic acid-poly(ϵ-caprolactone monolith osteochondral plug indicated for the repair of cartilage defects. The porous plug allows the continual transport of bone marrow constituents from the subchondral layer to the cartilage defect site for a more effective repair of the area. Assessment of the in vivo performance of the implant was conducted in an ovine model (n = 13. In addition to a control group (no implant, one group received the implant alone (Group A, while another group was supplemented with hyaluronic acid (0.8 mL at 10 mg/mL solution; Group B. Analyses performed on specimens from the in vivo study revealed that the implant achieves cartilage formation within 6 months. No adverse tissue reactions or other complications were reported. Our findings indicate that the porous biocompatible implant seems to be a promising treatment option for the cartilage repair.

  14. The "Batman flap": a novel technique to repair a large central glabellar defect.

    Science.gov (United States)

    Puviani, Mario; Curci, Marco

    2017-12-02

    Given the critical position of central glabella among the frontal, nasal, and supraorbital aesthetic subunits of the face, the reconstruction of large defects in this area represents a surgical challenge. We describe a surgical technique based on a modified, curved, A-T flap to repair a large glabellar defect. Our modification is useful for large glabellar defects because it enables the distribution of the tension all over the reconstruction sides, avoiding a stressed central area and the subsequent risk of necrosis; functionally, it respects the eyebrows position and since the advancement is parallel to their major axes, it avoids the reduction of the distance between them. The "Batman flap" enables reconstructing a glabellar defect, with a good aesthetical result and the respect of the relevant aesthetical subunits. © 2017 The International Society of Dermatology.

  15. A biomechanic study of the surgical repair technique of pars defect in spondylolysis.

    Science.gov (United States)

    Vathana, P; Prasartritha, T

    1998-11-01

    To find out which wiring technique of direct repair of the pars defect is the strongest in resisting anteroposterior translation displacement, fifteen fresh human cadaveric L4-L5 spines were biomechanically tested by a universal testing machine. Two millimeters wide pars defect was created on both sides of L4 vertebrae. Each of the five specimens was wired using Nicol's technique (A), modified Nicol's technique (B) and modified pedicular screw technique respectively (C). At each test, motion was observed to occur initially at the pars defect. The mean minimum tensile strength (increment of the pars defect) for technique A, B and C was 87.64, 82.04 and 110.08 Kg Force respectively. By statistical analysis, technique C was the strongest in resisting anteroposterior displacement of the spinal column. There was no statistically significant difference between technique A and B.

  16. Repair of massively defected hemi-joints using demineralized osteoarticular allografts with protected cartilage.

    Science.gov (United States)

    Li, Siming; Yang, Xiaohong; Tang, Shenghui; Zhang, Xunmeng; Feng, Zhencheng; Cui, Shuliang

    2015-08-01

    Surgical replacement of massively defected joints necessarily relies on osteochondral grafts effective to both of bone and cartilage. Demineralized bone matrix (DBM) retains the osteoconductivity but destroys viable chondrocytes in the cartilage portion essential for successful restoration of defected joints. This study prepared osteochondral grafts of DBM with protected cartilage. Protected cartilage portions was characterized by cellular and molecular biology and the grafts were allogenically used for grafting. Protected cartilage showed similar histomorphological structure and protected proteins estimated by total proteins and cartilage specific proteins as in those of fresh controls when DBMs were generated in bone portions. Such grafts were successfully used for simultaneously repair of bone and cartilage in massively defected osteoarticular joints within 16 weeks post-surgery. These results present an allograft with clinical potential for simultaneous restoration of bone and cartilage in defected joints.

  17. Comparative study of the application of microcurrent and AsGa 904 nm laser radiation in the process of repair after calvaria bone excision in rats

    Science.gov (United States)

    Mendonça, J. S.; Neves, L. M. G.; Esquisatto, M. A. M.; Mendonça, F. A. S.; Santos, G. M. T.

    2013-03-01

    This study evaluated the effects of microcurrent stimulation (10 μA/5 min) and 904 nm GaAs laser irradiation (3 J cm-2 for 69 s/day) on excisional lesions created in the calvaria bone of Wistar rats. The results showed significant responses in the reduction of inflammatory cells and an increase in the number of new blood vessels, number of fibroblasts and deposition of birefringent collagen fibers when these data were compared with those of samples of the untreated lesions. Both applications, microcurrent and laser at 904 nm, favored tissue repair in the region of bone excisions during the study period and these techniques can be used as coadjuvantes in the repair of bone tissue.

  18. Developmental defects and male sterility in mice lacking the ubiquitin-like DNA repair gene mHR23B.

    NARCIS (Netherlands)

    J.M.Y. Ng (Jessica); H. Vrieling (Harry); K. Sugasawa (Kaoru); M.P. Ooms (Marja); J.A. Grootegoed (Anton); J.T.M. Vreeburg (Jan); P. Visser (Pim); R.B. Beems (Rudolf); T.G.M.F. Gorgels (Theo); F. Hanaoka (Fumio); J.H.J. Hoeijmakers (Jan); G.T.J. van der Horst (Gijsbertus)

    2002-01-01

    textabstractmHR23B encodes one of the two mammalian homologs of Saccharomyces cerevisiae RAD23, a ubiquitin-like fusion protein involved in nucleotide excision repair (NER). Part of mHR23B is complexed with the XPC protein, and this heterodimer functions as the main damage detector and initiator of

  19. V-Y advancement flaps for extensive perianal defect repair.

    Science.gov (United States)

    Ibañez, Noelia; Abrisqueta, Jesús; Luján, Juan; Hernández, Quiteria; Parrilla, Pascual

    2016-11-01

    Some perianal pathologies require aggressive surgery that will need techniques to allow to re-establish the integrity of the perianal region. The purpose is to analyze short and long term results after perineal reconstruction with V-Y flaps. A retrospective review of prospectively collected database was conducted at Virgen de la Arrixaca's Hospital in Murcia (España) between January 2000 and December 2013. The study includes all patients who underwent a perineal reconstruction with V-Y flaps. Demographic and surgical data and short-/long- term morbidity was recorded. 10 patients were included, 6 males and 4 females. The average age was 58,1±17,4 years. Surgical indication included both malignant and benign pathologies. Operating time was 143,5±41,3min. R0 resection was performed in all cases although histopathological analysis showed involvement of the deeper margin in 3 cases. Length of hospital stay was 7,8±7,6 days. Regarding complications: 6 patients had partial dehiscence of the flap. None of the patients lost the flap completely. The most frequent late complication was anal stenosis (n=4). Follow up showed total continence in 7 patients. Two patients had variable fecal and/or flatus incontinence. A colostomy was made in one case due to severe incontinence. V-Y flaps are an effective and feasible technique to cover large perianal defects after aggressive surgeries. However, this technique is not free of postoperative morbidity. Copyright © 2016 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

  20. Clinical Evaluation of a New Bilayer Artificial Dermis for Repair of Oral Mucosal Defects: Report of two Cases

    Directory of Open Access Journals (Sweden)

    Chun-Ming Chen

    2004-10-01

    Full Text Available Free mucosal grafts or split-thickness skin grafts have been used in patients undergoing repair procedures for oral mucosal defects. Conventional methods require the creation of second surgical wounds for use as donor sites. We applied two bilayers of artificial dermis to repair a buccal mucosal defect in one case and vestibular extension in another case. After removal of the sutures, no infection, pain, or hemorrhage developed in these patients. The results of granulation and epithelialization were good. Satisfactory appearance and function were achieved in both cases. Therefore, bilayer artificial dermis may be recommended for the repair of oral mucosal defects.

  1. The DNA repair endonuclease XPG interacts directly and functionally with the WRN helicase defective in Werner syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Trego, Kelly S.; Chernikova, Sophia B.; Davalos, Albert R.; Perry, J. Jefferson P.; Finger, L. David; Ng, Cliff; Tsai, Miaw-Sheue; Yannone, Steven M.; Tainer, John A.; Campisi, Judith; Cooper, Priscilla K.

    2011-04-20

    XPG is a structure-specific endonuclease required for nucleotide excision repair (NER). XPG incision defects result in the cancer-prone syndrome xeroderma pigmentosum, whereas truncating mutations of XPG cause the severe postnatal progeroid developmental disorder Cockayne syndrome. We show that XPG interacts directly with WRN protein, which is defective in the premature aging disorder Werner syndrome, and that the two proteins undergo similar sub-nuclear redistribution in S-phase and co-localize in nuclear foci. The co-localization was observed in mid- to late-S-phase, when WRN moves from nucleoli to nuclear foci that have been shown to contain protein markers of both stalled replication forks and telomeric proteins. We mapped the interaction between XPG and WRN to the C-terminal domains of each and show that interaction with the C-terminal domain of XPG strongly stimulates WRN helicase activity. WRN also possesses a competing DNA single-strand annealing activity that, combined with unwinding, has been shown to coordinate regression of model replication forks to form Holliday junction/chicken foot intermediate structures. We tested whether XPG stimulated WRN annealing activity and found that XPG itself has intrinsic strand annealing activity that requires the unstructured R- and C-terminal domains, but not the conserved catalytic core or endonuclease activity. Annealing by XPG is cooperative, rather than additive, with WRN annealing. Taken together, our results suggest a novel function for XPG in S-phase that is at least in part carried out coordinately with WRN, and which may contribute to the severity of the phenotypes that occur upon loss of XPG.

  2. The application of computer-aided designated titanium mesh in repairing skull defects

    Directory of Open Access Journals (Sweden)

    Lei ZHANG

    2015-01-01

    Full Text Available Objective To explore the clinical value of repairing skull defects with titanium alloy-mesh of computer-aided design.  Methods A retrospective analysis was done on clinical data of 86 cases with skull defects who underwent repairing using titanium mesh with two-dimensional or three-dimensional computer-aided design.  Results All the incisions achieved primary healing other than one case conducting reoperation due to exposed titanium mesh. Two cases got subcutaneous exudate, one obtained painful mastication and one experienced proliferation of scalp scar.  Conclusions With the computer-aided designated titanium mesh, relevant operation can resume the original state to maximum extent, lower surgical risk, decrease post-operational complications and then obtain satisfying clinical effect. DOI: 10.3969/j.issn.1672-6731.2015.01.015

  3. [Removal of laryngeal cancer with thyroid cartilage membrane excision and repair of laryngeal cavity with outside thyroid cartilage membrane flap of healthy side: oncologic and functional outcomes].

    Science.gov (United States)

    Zhong, Z T; Liang, M Z; Chen, Z

    2016-08-07

    To study the efficacy and feasibility of removal of laryngeal cancer with thyroid cartilage membrane excision and repair of laryngeal cavity by the outside thyroid cartilage membrane flap of healthy side. A total of 28 patients were reviewed who underwent the removal of laryngeal cancer with thyroid cartilage membrane excision combined with the repair of laryngeal cavity by the outside thyroid cartilage membrane flap in our hospital between 2005 and 2011. Respiratory function, swallowing function, and voice quality of patients after surgery were evaluated. Survival and recurrence were observed with the follow up of five years. The decannulation rate was 96.4%. Aspiration rate was 10.7%, but aspiration was completely revolved by swallowing training in the patients. All patients had the voice quality required for communication although they complained of hoarseness after surgery. Tumor recurrence was found in one patient and cervical lymph node metastasis in 2 patients. The three-year and five-year survival rates were 89.3% and 85.7% respectively. This surgical procedure was applicable in some of patients with T2 laryngeal cancer, with good laryngeal functions after surgery.

  4. Genetic polymorphisms in DNA base excision repair gene XRCC1 and the risk of squamous cell carcinoma of the head and neck

    Directory of Open Access Journals (Sweden)

    Pietruszewska Wioletta

    2009-03-01

    Full Text Available Abstract Background The genes of base excision repair (BER pathway have been extensively studied in the association with various human cancers. We performed a case-control study to test the association between two common single nucleotide polymorphisms (SNPs of XRCC1 gene with human head and neck squamous cell carcinoma (HNSCC. Methods The genotype analysis of Arg194Trp and Arg399Gln gene polymorphisms for 92 HNSCC patients and 124 controls of cancer free subjects, in Polish population were performed using the PCR-based restriction fragment length polymorphism (PCR-RFLP with endonuclease MspI. Results No altered risk has been found individually for these SNPs, however haplotypes analysis showed high association with head and neck cancer. The highest frequency, according to wild-type of Arg194Arg and Arg399Arg genotypes, was identified for Arg194Trp-Arg399Arg haplotype (OR, 2.96; 95% CI, 1.01–8.80. Conclusion Finally, we identified the combined Arg194Trp-Arg399Arg genotype of base excision repair gene XRCC1 that was associated with HNSCC and may have an impact on identification of a high-risk cancer population.

  5. The Effect of Msh2 Knockdown on Toxicity Induced by tert-Butyl-hydroperoxide, Potassium Bromate, and Hydrogen Peroxide in Base Excision Repair Proficient and Deficient Cells

    Directory of Open Access Journals (Sweden)

    N. Cooley

    2013-01-01

    Full Text Available The DNA mismatch repair (MMR and base excision repair (BER systems are important determinants of cellular toxicity following exposure to agents that cause oxidative DNA damage. To examine the interactions between these different repair systems, we examined whether toxicity, induced by t-BOOH and KBrO3, differs in BER proficient (Mpg+/+, Nth1+/+ and deficient (Mpg−/−, Nth1−/− mouse embryonic fibroblasts (MEFs following Msh2 knockdown of between 79 and 88% using an shRNA expression vector. Msh2 knockdown in Nth1+/+ cells had no effect on t-BOOH and KBrO3 induced toxicity as assessed by an MTT assay; knockdown in Nth1−/− cells resulted in increased resistance to t-BOOH and KBrO3, a result consistent with Nth1 removing oxidised pyrimidines. Msh2 knockdown in Mpg+/+ cells had no effect on t-BOOH toxicity but increased resistance to KBrO3; in Mpg−/− cells, Msh2 knockdown increased cellular sensitivity to KBrO3 but increased resistance to t-BOOH, suggesting a role for Mpg in removing DNA damage induced by these agents. MSH2 dependent and independent pathways then determine cellular toxicity induced by oxidising agents. A complex interaction between MMR and BER repair systems, that is, exposure dependent, also exists to determine cellular toxicity.

  6. The Effect of Msh2 Knockdown on Toxicity Induced by tert-Butyl-hydroperoxide, Potassium Bromate, and Hydrogen Peroxide in Base Excision Repair Proficient and Deficient Cells

    Science.gov (United States)

    Cooley, N.; Elder, R. H.; Povey, A. C.

    2013-01-01

    The DNA mismatch repair (MMR) and base excision repair (BER) systems are important determinants of cellular toxicity following exposure to agents that cause oxidative DNA damage. To examine the interactions between these different repair systems, we examined whether toxicity, induced by t-BOOH and KBrO3, differs in BER proficient (Mpg +/+, Nth1 +/+) and deficient (Mpg −/−, Nth1 −/−) mouse embryonic fibroblasts (MEFs) following Msh2 knockdown of between 79 and 88% using an shRNA expression vector. Msh2 knockdown in Nth1 +/+ cells had no effect on t-BOOH and KBrO3 induced toxicity as assessed by an MTT assay; knockdown in Nth1 −/− cells resulted in increased resistance to t-BOOH and KBrO3, a result consistent with Nth1 removing oxidised pyrimidines. Msh2 knockdown in Mpg +/+ cells had no effect on t-BOOH toxicity but increased resistance to KBrO3; in Mpg −/− cells, Msh2 knockdown increased cellular sensitivity to KBrO3 but increased resistance to t-BOOH, suggesting a role for Mpg in removing DNA damage induced by these agents. MSH2 dependent and independent pathways then determine cellular toxicity induced by oxidising agents. A complex interaction between MMR and BER repair systems, that is, exposure dependent, also exists to determine cellular toxicity. PMID:23984319

  7. hWJECM-Derived Oriented Scaffolds with Autologous Chondrocytes for Rabbit Cartilage Defect Repairing.

    Science.gov (United States)

    Zhao, Peng; Liu, Shuyun; Bai, Yuhe; Lu, Shibi; Peng, Jiang; Zhang, Li; Huang, Jingxiang; Zhao, Bin; Xu, Wenjing; Guo, Quanyi

    2018-02-02

    Previously, we synthesized an articular cartilage extracellular matrix (ECM)-derived oriented scaffold for cartilage tissue engineering, which was biomimetic in terms of structure and biochemical composition. However, the limit resource of the cartilage-derived ECM is a hindrance for its application. In this study, we developed a new material for cartilage tissue engineering-human umbilical cord Wharton's jelly-derived ECM (hWJECM). The hWJECM has an abundant resource and similar biochemistry with cartilage ECM, and the use of it is not associated with ethical controversy. We adopted the method previously used in cartilage ECM-derived oriented scaffold preparation to generate the oriented hWJECM-derived scaffold, and the scaffold properties were tested in vitro and in vivo. The three-dimensional scaffold has a porous and well-oriented structure, with a mean pore diameter of ∼104 μm. Scanning electron microscopy and cell viability staining results demonstrated that the oriented scaffold has good biocompatibility and cell alignment. In addition, we used functional autologous chondrocytes to seed the hWJECM-derived oriented scaffold and tested the efficacy of the cell-scaffold constructs to repair the full-thickness articular cartilage defect in a rabbit model. Defects of 4 mm diameter were generated in the patellar grooves of the femurs of both knees and were implanted with chondrocyte-scaffold constructs (group A) or scaffolds alone (group B); rabbits with untreated defects were used as a control (group C). Six months after surgery, all defects in group A were filled completely with repaired tissue, and most of which were hyaline cartilage. In contrast, the defects in group B were filled partially with repaired tissue, and approximately half of these repaired tissues were hyaline cartilage. The defects in group C were only filled with fibrotic tissue. Histological grading score of group A was lower than those of groups B and C. Quantification of

  8. Polymers in Cartilage Defect Repair of the Knee: Current Status and Future Prospects

    Directory of Open Access Journals (Sweden)

    Ralph M. Jeuken

    2016-06-01

    Full Text Available Cartilage defects in the knee are often seen in young and active patients. There is a need for effective joint preserving treatments in patients suffering from cartilage defects, as untreated defects often lead to osteoarthritis. Within the last two decades, tissue engineering based techniques using a wide variety of polymers, cell sources, and signaling molecules have been evaluated. We start this review with basic background information on cartilage structure, its intrinsic repair, and an overview of the cartilage repair treatments from a historical perspective. Next, we thoroughly discuss polymer construct components and their current use in commercially available constructs. Finally, we provide an in-depth discussion about construct considerations such as degradation rates, cell sources, mechanical properties, joint homeostasis, and non-degradable/hybrid resurfacing techniques. As future prospects in cartilage repair, we foresee developments in three areas: first, further optimization of degradable scaffolds towards more biomimetic grafts and improved joint environment. Second, we predict that patient-specific non-degradable resurfacing implants will become increasingly applied and will provide a feasible treatment for older patients or failed regenerative treatments. Third, we foresee an increase of interest in hybrid construct, which combines degradable with non-degradable materials.

  9. New analysis tools and processes for mask repair verification and defect disposition based on AIMS images

    Science.gov (United States)

    Richter, Rigo; Poortinga, Eric; Scheruebl, Thomas

    2009-10-01

    Using AIMSTM to qualify repairs of defects on photomasks is an industry standard. AIMSTM images match the lithographic imaging performance without the need for wafer prints. Utilization of this capability by photomask manufacturers has risen due to the increased complexity of layouts incorporating RET and phase shift technologies. Tighter specifications by end-users have pushed AIMSTM analysis to now include CD performance results in addition to the traditional intensity performance results. Discussed is a new Repair Verification system for automated analysis of AIMSTM images. Newly designed user interfaces and algorithms guide users through predefined analysis routines as to minimize errors. There are two main routines discussed, one allowing multiple reference sites along with a test/defect site within a single image of repeating features. The second routine compares a test/defect measurement image with a reference measurement image. Three evaluation methods possible with the compared images are discussed in the context of providing thorough analysis capability. This paper highlights new functionality for AIMSTM analysis. Using structured analysis processes and innovative analysis tools leads to a highly efficient and more reliable result reporting of repair verification analysis.

  10. RESIDUAL DEFECTS AFTER SURGICAL REPAIR OF VENTRICULAR SEPTAL DEFECTS IN CHILDREN:

    Directory of Open Access Journals (Sweden)

    K Sayadpour-Zanjani

    2008-12-01

    Full Text Available "nResidual ventricular septal defects (VSD are major complications after cardiac surgery. We studied the incidence of this complication, risk factors for its occurrence and short-term follow-up in 179 pediatric patients that underwent surgical closure of VSD from April 2003 until May 2004. All data were gathered retrospectively except measurements of shunt ratio. Studied risk factors included age, sex, weight, height, ejection fraction, VSD size, presence of pulmonary stenosis (PS, responsible surgeon, use of patch material for closing VSD, mean degree of hypothermia, cardiopulmonary bypass and aortic cross-clamp times, hemorrhage, documented infection, and surgical approach for defect closure. The incidence of all residual VSDs was 56% and significant ones (i.e. with Qp/Qs > 1.5 22%. The only statistically significant risk factors were higher age, weigh and height of the patients. There was notable but statistically insignificant differences in residual shunt incidence among the patients of different surgeons and with the use of different patch materials. During the median follow-up period of 9.5 months, 35% of the residual defects were closed spontaneously. Six patients underwent catheterization, three of which were candidates of residual VSD closure. As residual VSD is a hemodynamically and psychologically important complication, we recommend VSD closure at lower age and the use of intraoperative epicardial or transesophageal echocardiography to minimize its occurrence.

  11. [FREE CROIN FLAP FOR REPAIRING DEFECTS OF DONOR AFTER TOE TISSUE TRANSPLANTATION].

    Science.gov (United States)

    Li, Muwei; Luo Zhaohui; Gu, Hannan; Ma, Lifeng; Yang, Yanjun; Zhang, Ziqing

    2016-02-01

    To discuss the effectiveness of free croin flap in repairing defects of donor after toe or feetissue flap transplantation. Between March 2010 and May 2015, 23 cases of defects of donor after toe or feet tissue flap transplantation were repaired with free croin flap and followed up for more than 6 months, and the clinical data were retrospectively analyzed. There were 15 males and 8 females, with an age range from 17 to 52 years (mean, 25.6 years). All finger or soft tissue defects were caused by trauma. Defects were repaired in emergency operation with toe or feet tissue flap transplantation in 18 cases, defects were secondarily reconstructed at 3-8 months after injury in 5 cases. The defect area at the feet donor site ranged from 3 cmx3 cm to 10 cmx6 cm, all accompanied with exposure of bone, and tendon. The area of free croin flap was 3.5 cm x 3.5 cm-11.0 cm x 6.5 cm, the vessel of flap was anastomosed with artery and vein of foot. The inguinal donor site was sutured directly. The operation time was 3-9 hours (mean, 4.5 hours); the intraoperative blood loss was 50-300 mL (mean, 120 mL). Vessel crisis occurred in 1 case postoperatively; mild and moderate swelling occurred in 3 cases, with small sporadic blisters formation; free croin flap survived completely in the other cases, and primary healing was obtained at feet wound and inguinal donor sites. Twenty-three cases were followed up 6-24 months (mean, 9 months). The color and texture of the croin flaps were similar to that of the adjacent skin, no obvious scar contracture and pigmentation were observed; the patient could walk with weight loading, the two-point discrimination was 18-35 mm (mean, 26 mm) at 6 months after operation. The color, texture, and shape of reconstructed finger was good; the function of grasping and pinching recovered well; the two-point discrimination was 5.5-11.0 mmfunctional evaluation standard by Chinese Medical Association, the results were excellent in 18 cases and good in 5 cases

  12. Effect of dolomite on the repair of bone defects in rats: histological study.

    Science.gov (United States)

    Moreschi, Eduardo; Hernandes, Luzmarina; Dantas, Jailson Araujo; da Silva, Maria Angélica Raffaini Covas Pereira; Casaroto, Ana Regina; Bersani-Amado, Ciomar Aparecida

    2010-12-01

    The aim of the present study was to evaluate histologically and radiographically the tissue response to dolomite [CaMg(CO3)2] and its osteogenic potential in the repair of bone cavities in the calvaria of rats. A bone defect 10 mm in diameter and 1 mm deep was made in the calvaria of male Wistar rats. The defects were filled with dolomite, inorganic bovine bone (positive control), or coagulum (negative control). The animals were euthanized 7, 15, 30, and 60 days after surgery, and specimens were collected for radiographic and microscopic analyses. The bone defects were processed for paraffin embedding and H&E staining. The histological study revealed that dolomite stimulated a moderate inflammatory response, with programmed cell death in the first 15 days, compared to bovine bone which showed a moderate to intense acute response. In the chronic phase, the inflammatory response was characterized by the occurrence of macrophages organized as epithelioid cells in the dolomite group, and giant cells in the bovine-bone group. Fibrosis developed in all three groups; however, encapsulation of the fragments, reabsorption, and osteoconductive activity occurred only in the defects filled with bovine bone. The radiographic analysis showed that the bovine bone was most efficient in the repair of the defects, followed by the dolomite and the coagulum. This study demonstrated that the dolomite stimulated a moderate acute inflammatory response with programmed cell death, and a chronic inflammatory response by means of the phagocytic mononuclear system. Although osteo-conductive activity was not shown, the dolomite favored the repair process, compared to the coagulum group.

  13. [Repair of soft tissue defect in finger with modified reverse dorsal digital fascia flap].

    Science.gov (United States)

    Li, Zhian; Li, Zhenwu; Zhang, Guiping

    2009-06-01

    To investigate the operative method of repairing soft tissue defect of finger with modified reverse dorsal digital fascia flap and its clinical effect of preventing and treating venous crisis. From February 2005 to March 2007, 19 cases (22 fingers) with soft tissue defect of finger were treated, including 14 males (17 fingers) and 5 females (5 fingers) aged 2-62 years old (median 26 years old). There were 8 cases of cutting injury, 6 cases of crush injury, 4 cases of avulsion injury, and 1 case of hot crush injury, involving 3 thumbs, 7 index fingers, 6 middle fingers, 4 ring fingers and 2 little fingers. The size of soft tissue defect was 1.5 cm x 0.8 cm-5.5 cm x 1.5 cm, and the time from injury to operation was 2-11 hours (average 7 hours). The axis of flaps was the line of transverse striation of fingers via dominant artery. The flaps were deflected dorsally, as "b" or "d", to cover the wounds. Reverse dorsal digital fascia flaps 1.8 cm x 1.0 cm-6.0 cm x 2.0 cm in size were Radopted to repair the defects. The donor site underwent skin grafting fixation. All flaps survived, without venous acrisis and obvious swollen. The grafted skin in the donor site all survived. All patients were followed for 6-18 months (average 11 months). Postoperatively, color and texture of the grafted flaps were similar to that of normal skin, and the pulp of the fingers was normal. The two-point discrimination was 8-11 mm, and the activities of interphalangeal joint of all injured fingers were normal. The modified reverse dorsal digital fascia flap is ideal for repairing soft tissues defects of the fingers, and can decrease the occurrence of venous crisis.

  14. Technical Report: Correlation Between the Repair of Cartilage and Subchondral Bone in an Osteochondral Defect Using Bilayered, Biodegradable Hydrogel Composites

    NARCIS (Netherlands)

    Lu, S.; Lam, J.; Trachtenberg, J.E.; Lee, E.J.; Seyednejad, H.; Beucken, J.J.J.P van den; Tabata, Y.; Kasper, F.K.; Scott, D.W.; Wong, M.E.; Jansen, J.A.; Mikos, A.G.

    2015-01-01

    The present work investigated correlations between cartilage and subchondral bone repair, facilitated by a growth factor-delivering scaffold, in a rabbit osteochondral defect model. Histological scoring indices and microcomputed tomography morphological parameters were used to evaluate cartilage and

  15. Repair of Double Orifice Left AV Valve (DOLAVV with Endocardial Cushion Defect in Adult

    Directory of Open Access Journals (Sweden)

    Vivek Velayudhan Pillai

    Full Text Available Abstract Double orifice left atrioventricular valve (DOLAVV or double orifice mitral valve (DOMV is a rare congenital cardiac anomaly manifesting either as an isolated lesion (mitral stenosis or mitral insufficiency or in association with other congenital cardiac defects. Signs of mitral valve disease are usually present along with the symptoms of associated coexistent congenital heart diseases. Mitral insufficiency due to annular dilatation is seen when DOLAVV is associated with endocardial cushion defects. Surgical intervention like mitral valve repair or replacement is required in 50% of patients and yields good results. We report a case of a 56-year-old lady who successfully underwent surgical correction of DOLAVV with partial atrioventricular canal defect.

  16. A modified infarct exclusion technique for repair of anteroapical postinfarction ventricular septal defect.

    Science.gov (United States)

    Bayezid, Omer; Turkay, Cengiz; Golbasi, Ilihan

    2005-01-01

    Ventricular septal defects complicate approximately 1% to 2% of cases of acute myocardial infarction. Such postinfarction defects require urgent surgical treatment because, on medical treatment alone, 60% to 70% of patients die within the first 2 weeks. Despite the development of various surgical techniques for repair of postinfarction ventricular septal defect, the condition carries a high risk of recurrence and subsequent death. We describe a modification of the infarct exclusion technique in which the septal portion of the patch is reinforced by the right ventricular free wall. This modification appears to prevent leaks to the right ventricle through the ventricular septal defect, from anywhere around the patch. We applied this modified technique to 4 patients with anteroapical postinfarction ventricular septal defect. There was 1 early death, due to mesenteric artery occlusion secondary to embolus. No residual shunt was found during the postoperative period. We believe that our modification to the infarct exclusion technique might reduce both operative mortality and recurrence, by supporting friable endocardial tissue with right ventricular wall. We suggest that it be considered for use in patients with anteroapical ventricular septal defect and no severe right ventricular dysfunction.

  17. In situ repair of bone and cartilage defects using 3D scanning and 3D printing.

    Science.gov (United States)

    Li, Lan; Yu, Fei; Shi, Jianping; Shen, Sheng; Teng, Huajian; Yang, Jiquan; Wang, Xingsong; Jiang, Qing

    2017-08-25

    Three-dimensional (3D) printing is a rapidly emerging technology that promises to transform tissue engineering into a commercially successful biomedical industry. However, the use of robotic bioprinters alone is not sufficient for disease treatment. This study aimed to report the combined application of 3D scanning and 3D printing for treating bone and cartilage defects. Three different kinds of defect models were created to mimic three orthopedic diseases: large segmental defects of long bones, free-form fracture of femoral condyle, and International Cartilage Repair Society grade IV chondral lesion. Feasibility of in situ 3D bioprinting for these diseases was explored. The 3D digital models of samples with defects and corresponding healthy parts were obtained using high-resolution 3D scanning. The Boolean operation was used to achieve the shape of the defects, and then the target geometries were imported in a 3D bioprinter. Two kinds of photopolymerized hydrogels were synthesized as bioinks. Finally, the defects of bone and cartilage were restored perfectly in situ using 3D bioprinting. The results of this study suggested that 3D scanning and 3D bioprinting could provide another strategy for tissue engineering and regenerative medicine.

  18. The genetic defect in Cockayne syndrome is associated with a defect in repair of UV-induced DNA damage in transcriptionally active DNA

    Energy Technology Data Exchange (ETDEWEB)

    Venema, J.; Mullenders, L.H.; Natarajan, A.T.; van Zeeland, A.A.; Mayne, L.V. (State Univ. of Leiden (Netherlands))

    1990-06-01

    Cells from patients with Cockayne syndrome (CS) are hypersensitive to UV-irradiation but have an apparently normal ability to remove pyrimidine dimers from the genome overall. We have measured the repair of pyrimidine dimers in defined DNA sequences in three normal and two CS cell strains. When compared to a nontranscribed locus, transcriptionally active genes were preferentially repaired in all three normal cell strains. There was no significant variation in levels of repair between various normal individuals or between two constitutively expressed genes, indicating that preferential repair may be a consistent feature of constitutively expressed genes in human cells. Neither CS strain, from independent complementation groups, was able to repair transcriptionally active DNA with a similar rate and to the same extent as normal cells, indicating that the genetic defect in CS lies in the pathway for repair of transcriptionally active DNA. These results have implications for understanding the pleiotropic clinical effects associated with disorders having defects in the repair of DNA damage. In particular, neurodegeneration appears to be associated with the loss of preferential repair of active genes and is not simply correlated with reduced levels of overall repair.

  19. Role of nucleotide excision repair and photoreactivation in the solar UVB radiation survival of Pseudomonas syringae pv. syringae B728a.

    Science.gov (United States)

    Gunasekera, T S; Sundin, G W

    2006-05-01

    To assess the role of DNA repair and photoreactivation in the solar radiation survival of the plant pathogen and leaf surface epiphyte Pseudomonas syringae pv. syringae (Pss). Mutants of Pss B728a, with insertional mutations within the nucleotide excision repair gene uvrA, photolyase gene phr, or uvrA phr double mutants, were constructed to examine the importance of individual repair mechanisms in solar UV radiation (UVR) survival. The survival of either the uvrA mutant or the phr mutant was reduced by approx. 10(2)-fold following exposure to a dose of 4.5 kJ m(-2) solar UVB (290-320 nm wavelengths) while the uvrA phr double mutant was reduced >10(6)-fold by the same dose. We constructed a transcriptional fusion between the Pss recA promoter and gfp to examine the induction of the SOS response in wild-type and mutant strains. Initiation of the recA mediated SOS response was more rapid and peaked at higher levels in mutant strains suggesting both increased DNA damage in mutant strains and also that photoreactivation and nucleotide excision repair remove DNA damage as it is incurred which is reflected in a delay of recA expression. Visualization of expression of B728a cells containing the recA::gfp reporter on UVB-irradiated bean leaves highlighted the movement of cells to intercellular spaces over time and that SOS induction was detectable when leaves were irradiated 48 h following leaf inoculation. This study indicated that solar UVB is detrimental to Pss B728a, DNA repair mechanisms play an important role in strain survival and expression of the SOS regulon on leaf surfaces contributes to survival of UVR-exposed cells during plant colonization. This work links previous laboratory-based UVR analyses with solar UVB dose-response analyses and highlights the role of photoreactivation in delaying induction of the SOS response following solar irradiation. Knowledge of population dynamics following direct solar irradiation will enhance our understanding of the biology of

  20. Evaluation of porous gradient hydroxyapatite/zirconia composites for repair of lumbar vertebra defect in dogs.

    Science.gov (United States)

    Shao, Rong-Xue; Quan, Ren-Fu; Huang, Xiao-Long; Wang, Tuo; Xie, Shang-Ju; Gao, Huan-Huan; Wei, Xi-Cheng; Yang, Di-Sheng

    2016-04-01

    To evaluate the effects of porous gradient composites with hydroxyapatite/zirconia and autologous iliac in repair of lumbar vertebra body defects in dogs. (1) New porous gradient hydroxyapatite/zirconia composites were prepared using foam immersion, gradient compound and high temperature sintering; (2) A total of 18 adult beagle dogs, aged five to eight months and weighted 10-13 kg, were randomly assigned into two subgroups, which were implanted with new porous gradient hydroxyapatite/zirconia composites (subgroup A in 12) or autologous iliac bone (subgroup B in 6); (3) The post-operative data were analyzed and compared between the subgroups to repair the vertebral body defect by roentgenoscopy, morphology and biomechanics. The porosity of new porous gradient hydroxyapatite/zirconia composites is at 25 poles per inch, and the size of pores is at between 150 and 300 µm. The post-operative roentgenoscopy displayed that new-bone formation is increased gradually, and the interface between composites and host-bone becomes became blur, and the new-bone around the composites were integrated into host-bone at 24 weeks postoperatively in subgroup A. As to subgroup B, the resorption and restructure were found at six weeks after the surgery, and the graft-bone and host-bone have been integrated completely without obvious boundary at 24 weeks postoperatively. Histomorphologic study showed that the amount of bone within pores of the porous gradient hydroxyapatite/zirconia composites increased continuously with a prolonged implantation time, and that partial composites were degradated and replaced by new-bone trabeculae. There was no significant difference between subgroups (P > 0.05) in the ultimate compressive strengths. New porous gradient hydroxyapatite/zirconia composites can promote the repair of bony defect, and induce bone tissue to ingrow into the pores, which may be applied widely to the treatment of bony defect in the future. © The Author(s) 2016.

  1. ATP-Dependent Chromatin Remodeling Is Required for Base Excision Repair in Conventional but Not in Variant H2A.Bbd Nucleosomes▿

    Science.gov (United States)

    Menoni, Hervé; Gasparutto, Didier; Hamiche, Ali; Cadet, Jean; Dimitrov, Stefan; Bouvet, Philippe; Angelov, Dimitar

    2007-01-01

    In eukaryotes, base excision repair (BER) is responsible for the repair of oxidatively generated lesions. The mechanism of BER on naked DNA substrates has been studied in detail, but how it operates on chromatin remains unclear. Here we have studied the mechanism of BER by introducing a single 8-oxo-7,8-dihydroguanine (8-oxoG) lesion in the DNA of reconstituted positioned conventional and histone variant H2A.Bbd nucleosomes. We found that 8-oxoguanine DNA glycosylase, apurinic/apyrimidinic endonuclease, and polymerase β activities were strongly reduced in both types of nucleosomes. In conventional nucleosomes SWI/SNF stimulated the processing of 8-oxoG by each one of the three BER repair factors to efficiencies similar to those for naked DNA. Interestingly, SWI/SNF-induced remodeling, but not mobilization of conventional nucleosomes, was required to achieve this effect. A very weak effect of SWI/SNF on the 8-oxoG BER removal in H2A.Bbd histone variant nucleosomes was observed. The possible implications of our data for the understanding of in vivo mechanisms of BER are discussed. PMID:17591702

  2. Oxidative stress alters base excision repair pathway and increases apoptotic response in apurinic/apyrimidinic endonuclease 1/redox factor-1 haploinsufficient mice.

    Science.gov (United States)

    Unnikrishnan, Archana; Raffoul, Julian J; Patel, Hiral V; Prychitko, Thomas M; Anyangwe, Njwen; Meira, Lisiane B; Friedberg, Errol C; Cabelof, Diane C; Heydari, Ahmad R

    2009-06-01

    Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is the redox regulator of multiple stress-inducible transcription factors, such as NF-kappaB, and the major 5'-endonuclease in base excision repair (BER). We utilized mice containing a heterozygous gene-targeted deletion of APE1/Ref-1 (Apex(+/-)) to determine the impact of APE1/Ref-1 haploinsufficiency on the processing of oxidative DNA damage induced by 2-nitropropane (2-NP) in the liver tissue of mice. APE1/Ref-1 haploinsufficiency results in a significant decline in NF-kappaB DNA-binding activity in response to oxidative stress in liver. In addition, loss of APE1/Ref-1 increases the apoptotic response to oxidative stress, in which significant increases in GADD45g expression, p53 protein stability, and caspase activity are observed. Oxidative stress displays a differential impact on monofunctional (UNG) and bifunctional (OGG1) DNA glycosylase-initiated BER in the liver of Apex(+/-) mice. APE1/Ref-1 haploinsufficiency results in a significant decline in the repair of oxidized bases (e.g., 8-OHdG), whereas removal of uracil is increased in liver nuclear extracts of mice using an in vitro BER assay. Apex(+/-) mice exposed to 2-NP displayed a significant decline in 3'-OH-containing single-strand breaks and an increase in aldehydic lesions in their liver DNA, suggesting an accumulation of repair intermediates of failed bifunctional DNA glycosylase-initiated BER.

  3. DICER- and MMSET-catalyzed H4K20me2 recruits the nucleotide excision repair factor XPA to DNA damage sites.

    Science.gov (United States)

    Chitale, Shalaka; Richly, Holger

    2017-12-12

    Ultraviolet (UV) irradiation triggers the recruitment of DNA repair factors to the lesion sites and the deposition of histone marks as part of the DNA damage response. The major DNA repair pathway removing DNA lesions caused by exposure to UV light is nucleotide excision repair (NER). We have previously demonstrated that the endoribonuclease DICER facilitates chromatin decondensation during lesion recognition in the global-genomic branch of NER. Here, we report that DICER mediates the recruitment of the methyltransferase MMSET to the DNA damage site. We show that MMSET is required for efficient NER and that it catalyzes the dimethylation of histone H4 at lysine 20 (H4K20me2). H4K20me2 at DNA damage sites facilitates the recruitment of the NER factor XPA. Our work thus provides evidence for an H4K20me2-dependent mechanism of XPA recruitment during lesion recognition in the global-genomic branch of NER. © 2018 Chitale and Richly.

  4. Glucosamine and chondroitin sulfate in the repair of osteochondral defects in dogs - clinical-radiographic analysis

    Directory of Open Access Journals (Sweden)

    Renato Barros Eleotério

    2012-10-01

    Full Text Available Among the proposed treatments to repair lesions of degenerative joint disease (DJD, chondroprotective nutraceuticals composed by glucosamine and chondroitin sulfate are a non-invasive theraphy with properties that favors the health of the cartilage. Although used in human, it is also available for veterinary use with administration in the form of nutritional supplement independent of prescription, since they have registry only in the Inspection Service, which does not require safety and efficacy testing. The lack of such tests to prove efficacy and safety of veterinary medicines required by the Ministry of Agriculture and the lack of scientific studies proving its benefits raises doubts about the efficiency of the concentrations of such active substances. In this context, the objective of this study was to evaluate the efficacy of a veterinary chondroprotective nutraceutical based on chondroitin sulfate and glucosamine in the repair of osteochondral defects in lateral femoral condyle of 48 dogs, through clinical and radiographic analysis. The animals were divided into treatment group (TG and control group (CG, so that only the TG received the nutraceutical every 24 hours at the rate recommended by the manufacturer. The results of the four treatment times (15, 30, 60 and 90 days showed that the chondroprotective nutraceutical, in the rate, formulation and administration at the times used, did not improve clinical signs and radiologically did not influence in the repair process of the defects, since the treated and control groups showed similar radiographic findings at the end of the treatments.

  5. Miniplate fixation for the repair of segmental mandibular defects filled with autogenous bone in cats.

    Science.gov (United States)

    Silva, Adelina Maria da; Souza, Wilson Machado de; Koivisto, Marion Burkhardt de; Barnabé, Patrícia de Athayde; Souza, Nair Trevizan Machado de

    2011-06-01

    To evaluate the use of maxillofacial miniplate 1.5 in the repair of segmental mandibular defects filled with autogenous bone in cats. Twelve adult cats were divided into two groups. A segmental defect of 4mm was created in one of the hemimandibles and filled with autogenous iliac crest bone graft. The operated hemimandible was fixed with a 1.5mm titanium miniplate. In group 1 (n=6), the defect was performed in the body of the mandible, behind the 1st molar. In group 2 (n=6), the defect was performed between the 4nd premolar and 1st molar, with extraction of the 1st molar. Oral alimentation was reinitiated 24 hours after surgery. Cats were euthanized at 20 weeks postoperative. Incorporation of the graft was suggested by the radiographs taken 20 weeks after surgery. Macroscopic examination confirmed alignment and bone union of operated hemimandibles. Histological examination showed formation of woven bone in rostral and caudal mandible/graft interfaces. The percentage of bone tissue at these areas was measured by the histometry. There was no statistically significant difference between the values of group 1(64.48 ± 4.51) and group 2 (71.69 ± 14.47) (Mann-Whitney's test p= 0.294). The use of miniplate 1.5 for the fixation of mandibular defects filled with autogenous bone in cats provided the main goals in the treatment of mandibular fractures: bone union, normal dental occlusion and immediate return to oral alimentation.

  6. Mismatch repair defective breast cancer in the hereditary nonpolyposis colorectal cancer syndrome

    DEFF Research Database (Denmark)

    Jensen, Uffe Birk; Sunde, Lone; Timshel, Susanne

    2010-01-01

    Whether or not breast cancer can be a feature of the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome has been debated. In order to clarify if defective mismatch repair (MMR) may indeed play a role in breast cancer, we used the Danish HNPCC register to identify all breast cancers that o...... the low number do not motivate surveillance, our observation supports a role for defective MMR in breast cancer progression in HNPCC, presumably through accelerated accumulation of mutations in breast cancer-associated genes.......Whether or not breast cancer can be a feature of the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome has been debated. In order to clarify if defective mismatch repair (MMR) may indeed play a role in breast cancer, we used the Danish HNPCC register to identify all breast cancers...... that occurred in MMR gene mutation carriers. In total, 20 female mutation carriers were diagnosed with breast cancer at mean 50 years of age. These tumors were predominantly ductal carcinomas with extensive lymphocytic reactions in 8/14 evaluated tumors. MMR protein immunostaining showed loss of expression...

  7. Mirror-smooth surfaces and repair of defects in superconducting RF cavities by mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, C. A. [Fermilab; Cooley, L. D. [Fermilab

    2012-11-22

    Mechanical techniques for polishing the inside surface of niobium superconducting radio-frequency (SRF) cavities have been systematically explored. By extending known techniques to fine polishing, mirror-like finishes were produced, with <15 nm RMS (root mean square) roughness over 1 mm2 scan area. This is an order of magnitude less than the typical roughness produced by the electropolishing of niobium cavities. The extended mechanical polishing (XMP) process was applied to several SRF cavities which exhibited equator defects that caused quench at <20 MV m-1 and were not improved by further electropolishing. Cavity optical inspection equipment verified the complete removal of these defects, and minor acid processing, which dulled the mirror finish, restored performance of the defective cells to the high gradients and quality factors measured for adjacent cells when tested with other harmonics. This innate repair feature of XMP could be used to increase manufacturing yield. Excellent superconducting properties resulted after initial process optimization, with quality factor Q of 3 × 1010 and accelerating gradient of 43 MV m-1 being attained for a single-cell TESLA cavity, which are both close to practical limits. Several repaired nine-cell cavities also attained Q > 8 × 109 at 35 MV m-1, which is the specification for the International Linear Collider. Future optimization of the process and pathways for eliminating requirements for acid processing are also discussed.

  8. Repair of articular cartilage defects one year after treatment with recombinant human bone morphogenetic protein-2 (rhBMP-2).

    Science.gov (United States)

    Sellers, R S; Zhang, R; Glasson, S S; Kim, H D; Peluso, D; D'Augusta, D A; Beckwith, K; Morris, E A

    2000-02-01

    Damaged articular cartilage has a limited ability to repair. Operative removal of damaged cartilage and penetration into the subchondral bone to allow population of the defect with progenitor cells can result in filling of the defect with repair tissue. However, this repair tissue often degenerates over time because of its inability to withstand the mechanical forces to which it is subjected. We previously reported that recombinant human bone morphogenetic protein-2 (rhBMP-2) improves the repair of full-thickness defects of cartilage as long as six months postoperatively. We have now extended that study to examine the quality of the repair tissue at one year. Full-thickness defects of cartilage were created in the trochlear groove of twenty-five adult New Zealand White rabbits. Eight defects were left empty, eight were filled with a collagen sponge, and nine were filled with a collagen sponge impregnated with five micrograms of rhBMP-2. The animals were killed at fifty-two weeks postoperatively, and the gross appearance of the healed defect was assessed. The repair tissue was examined histologically and was evaluated, according to a grading scale, by four individuals who were blinded with respect to the treatment. The tissue sections were immunostained with antibodies against type-I collagen, type-II collagen, aggrecan, and link protein. The residence time of the rhBMP-2 in the cartilage defect was evaluated in vivo with use of scintigraphic imaging of radiolabeled protein. One year after a single implantation of a collagen sponge containing five micrograms of rhBMP-2, the defects had a significantly better histological appearance than the untreated defects (those left empty or filled with a collagen sponge). The histological features that showed improvement were integration at the margin, cellular morphology, architecture within the defect, and reformation of the tidemark. The total scores were also better for the defects treated with rhBMP-2 than for the

  9. Inorganic-organic shape memory polymers and foams for bone defect repairs

    Science.gov (United States)

    Zhang, Dawei

    The ultimate goal of this research was to develop a "self-fitting" shape memory polymer (SMP) scaffold for the repair of craniomaxillofacial (CMF) bone defects. CMF defects may be caused by trauma, tumor removal or congenital abnormalities and represent a major class of bone defects. Their repair with autografts is limited by availability, donor site morbidity and complex surgical procedures. In addition, shaping and positioning of these rigid grafts into irregular defects is difficult. Herein, we have developed SMP scaffolds which soften at T > ˜56 °C, allowing them to conformally fit into a bone defect. Upon cooling to body temperature, the scaffold becomes rigid and mechanically locks in place. This research was comprised of four major studies. In the first study, photocrosslinkable acrylated (AcO) SMP macromers containing a poly(epsilon-caprolactone) (PCL) segment and polydimethylsiloxane (PDMS) segments were synthesized with the general formula: AcO-PCL40-block-PDMS m-block-PCL40-OAc. By varying the PDMS segment length (m), solid SMPs with highly tunable mechanical properties and excellent shape memory abilities were prepared. In the second study, porous SMP scaffolds were fabricated based on AcO-PCL 40-block-PDMS37-block-PCL 40-OAc via a revised solvent casting particulate leaching (SCPL) method. By tailoring scaffold parameters including salt fusion, macromer concentration and salt size, scaffold properties (e.g. pore features, compressive modulus and shape memory behavior) were tuned. In the third study, porous SMP scaffolds were produced from macromers with variable PDMS segment lengths (m = 0 -- 130) via an optimized SCPL method. The impact on pore features, thermal, mechanical, and shape memory properties as well as degradation rates were investigated. In the final study, a bioactive polydopamine coating was applied onto pore surfaces of the SMP scaffold prepared from PCL diacrylate. The thin coating did not affect intrinsic bulk properties of the

  10. Base excision repair efficiency and mechanism in nuclear extracts are influenced by the ratio between volume of nuclear extraction buffer and nuclei-Implications for comparative studies

    DEFF Research Database (Denmark)

    Akbari, Mansour; Krokan, Hans E

    2012-01-01

    attention. Here we have examined BER activity of nuclear cell extracts from HeLa cells, using as substrate a circular DNA molecule with either uracil or an AP-site in a defined position. We show that BER activity of nuclear extracts from the same batch of cells varies inversely with the volume of nuclear......The base excision repair (BER) pathway corrects many different DNA base lesions and is important for genomic stability. The mechanism of BER cannot easily be investigated in intact cells and therefore in vitro methods that reflect the in vivo processes are in high demand. Reconstitution of BER...... using purified proteins essentially mirror properties of the proteins used, and does not necessarily reflect the mechanism as it occurs in the cell. Nuclear extracts from cultured cells have the capacity to carry out complete BER and can give important information on the mechanism. Furthermore...

  11. Alcohol-induced one-carbon metabolism impairment promotes dysfunction of DNA base excision repair in adult brain.

    Science.gov (United States)

    Fowler, Anna-Kate; Hewetson, Aveline; Agrawal, Rajiv G; Dagda, Marisela; Dagda, Raul; Moaddel, Ruin; Balbo, Silvia; Sanghvi, Mitesh; Chen, Yukun; Hogue, Ryan J; Bergeson, Susan E; Henderson, George I; Kruman, Inna I

    2012-12-21

    The brain is one of the major targets of chronic alcohol abuse. Yet the fundamental mechanisms underlying alcohol-mediated brain damage remain unclear. The products of alcohol metabolism cause DNA damage, which in conditions of DNA repair dysfunction leads to genomic instability and neural death. We propose that one-carbon metabolism (OCM) impairment associated with long term chronic ethanol intake is a key factor in ethanol-induced neurotoxicity, because OCM provides cells with DNA precursors for DNA repair and methyl groups for DNA methylation, both critical for genomic stability. Using histological (immunohistochemistry and stereological counting) and biochemical assays, we show that 3-week chronic exposure of adult mice to 5% ethanol (Lieber-Decarli diet) results in increased DNA damage, reduced DNA repair, and neuronal death in the brain. These were concomitant with compromised OCM, as evidenced by elevated homocysteine, a marker of OCM dysfunction. We conclude that OCM dysfunction plays a causal role in alcohol-induced genomic instability in the brain because OCM status determines the alcohol effect on DNA damage/repair and genomic stability. Short ethanol exposure, which did not disturb OCM, also did not affect the response to DNA damage, whereas additional OCM disturbance induced by deficiency in a key OCM enzyme, methylenetetrahydrofolate reductase (MTHFR) in Mthfr(+/-) mice, exaggerated the ethanol effect on DNA repair. Thus, the impact of long term ethanol exposure on DNA repair and genomic stability in the brain results from OCM dysfunction, and MTHFR mutations such as Mthfr 677C→T, common in human population, may exaggerate the adverse effects of ethanol on the brain.

  12. Long-term anisotropic mechanical response of surgical meshes used to repair abdominal wall defects.

    Science.gov (United States)

    Hernández-Gascón, B; Peña, E; Pascual, G; Rodríguez, M; Bellón, J M; Calvo, B

    2012-01-01

    Routine hernia repair surgery involves the implant of synthetic mesh. However, this type of procedure may give rise to pain and bowel incarceration and strangulation, causing considerable patient disability. The purpose of this study was to compare the long-term behaviour of three commercial meshes used to repair the partially herniated abdomen in New Zealand White rabbits: the heavyweight (HW) mesh, Surgipro(®) and lightweight (LW) mesh, Optilene(®), both made of polypropylene (PP), and a mediumweight (MW) mesh, Infinit(®), made of polytetrafluoroethylene (PTFE). The implanted meshes were mechanical and histological assessed at 14, 90 and 180 days post-implant. This behaviour was compared to the anisotropic mechanical behaviour of the unrepaired abdominal wall in control non-operated rabbits. Both uniaxial mechanical tests conducted in craneo-caudal and perpendicular directions and histological findings revealed substantial collagen growth over the repaired hernial defects causing stiffness in the repair zone, and thus a change in the original properties of the meshes. The mechanical behaviour of the healthy tissue in the craneo-caudal direction was not reproduced by any of the implanted meshes after 14 days or 90 days of implant, whereas in the perpendicular direction, SUR and OPT achieved similar behaviour. From a mechanical standpoint, the anisotropic PP-lightweight meshes may be considered a good choice in the long run, which correlates with the structure of the regenerated tissue. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Base-Excision-Repair-Induced Construction of a Single Quantum-Dot-Based Sensor for Sensitive Detection of DNA Glycosylase Activity.

    Science.gov (United States)

    Wang, Li-Juan; Ma, Fei; Tang, Bo; Zhang, Chun-Yang

    2016-08-02

    DNA glycosylase is an initiating enzyme of cellular base excision repair pathway which is responsible for the repair of various DNA lesions and the maintenance of genomic stability, and the dysregulation of DNA glycosylase activity is associated with a variety of human pathology. Accurate detection of DNA glycosylase activity is critical to both clinical diagnosis and therapeutics, but conventional methods for the DNA glycosylase assay are usually time-consuming with poor sensitivity. Here, we demonstrate the base-excision-repair-induced construction of a single quantum dot (QD)-based sensor for highly sensitive measurement of DNA glycosylase activity. We use human 8-oxoguanine-DNA glycosylase 1 (hOGG1), which is responsible for specifically repairing the damaged 8-hydroxyguanine (8-oxoG, one of the most abundant and widely studied DNA damage products), as a model DNA glycosylase. In the presence of biotin-labeled DNA substrate, the hOGG1 may catalyze the removal of 8-oxo G from 8-oxoG·C base pairs to generate an apurinic/apyrimidinic (AP) site. With the assistance of apurinic/apyrimidinic endonuclease (APE1), the cleavage of the AP site results in the generation of a single-nucleotide gap. Subsequently, DNA polymerase β incorporates a Cy5-labeled dGTP into the DNA substrate to fill the gap. With the addition of streptavidin-coated QDs, a QD-DNA-Cy5 nanostructure is formed via specific biotin-streptavidin binding, inducing the occurrence of fluorescence resonance energy transfer (FRET) from the QD to Cy5. The resulting Cy5 signal can be simply monitored by total internal reflection fluorescence (TIRF) imaging. The proposed method enables highly sensitive measurement of hOGG1 activity with a detection limit of 1.8 × 10(-6) U/μL. Moreover, it can be used to measure the enzyme kinetic parameters and detect the hOGG1 activity in crude cell extracts, offering a powerful tool for biomedical research and clinical diagnosis.

  14. Bypass of a 5',8-cyclopurine-2'-deoxynucleoside by DNA polymerase β during DNA replication and base excision repair leads to nucleotide misinsertions and DNA strand breaks.

    Science.gov (United States)

    Jiang, Zhongliang; Xu, Meng; Lai, Yanhao; Laverde, Eduardo E; Terzidis, Michael A; Masi, Annalisa; Chatgilialoglu, Chryssostomos; Liu, Yuan

    2015-09-01

    5',8-Cyclopurine-2'-deoxynucleosides including 5',8-cyclo-dA (cdA) and 5',8-cyclo-dG (cdG) are induced by hydroxyl radicals resulting from oxidative stress such as ionizing radiation. 5',8-cyclopurine-2'-deoxynucleoside lesions are repaired by nucleotide excision repair with low efficiency, thereby leading to their accumulation in the human genome and lesion bypass by DNA polymerases during DNA replication and base excision repair (BER). In this study, for the first time, we discovered that DNA polymerase β (pol β) efficiently bypassed a 5'R-cdA, but inefficiently bypassed a 5'S-cdA during DNA replication and BER. We found that cell extracts from pol β wild-type mouse embryonic fibroblasts exhibited significant DNA synthesis activity in bypassing a cdA lesion located in replication and BER intermediates. However, pol β knock-out cell extracts exhibited little DNA synthesis to bypass the lesion. This indicates that pol β plays an important role in bypassing a cdA lesion during DNA replication and BER. Furthermore, we demonstrated that pol β inserted both a correct and incorrect nucleotide to bypass a cdA at a low concentration. Nucleotide misinsertion was significantly stimulated by a high concentration of pol β, indicating a mutagenic effect induced by pol β lesion bypass synthesis of a 5',8-cyclopurine-2'-deoxynucleoside. Moreover, we found that bypass of a 5'S-cdA by pol β generated an intermediate that failed to be extended by pol β, resulting in accumulation of single-strand DNA breaks. Our study provides the first evidence that pol β plays an important role in bypassing a 5',8-cyclo-dA during DNA replication and repair, as well as new insight into mutagenic effects and genome instability resulting from pol β bypassing of a cdA lesion. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Probing for DNA damage with β-hairpins: Similarities in incision efficiencies of bulky DNA adducts by prokaryotic and human nucleotide excision repair systems in vitro

    Science.gov (United States)

    Liu, Yang; Reeves, Dara; Kropachev, Konstantin; Cai, Yuqin; Ding, Shuang; Kolbanovskiy, Marina; Kolbanovskiy, Alexander; Bolton, Judith L.; Broyde, Suse; Van Houten, Bennett; Geacintov, Nicholas E.

    2011-01-01

    Nucleotide excision repair (NER) is an important prokaryotic and eukaryotic defense mechanism that removes a large variety of structurally distinct lesions in cellular DNA. While the proteins involved are completely different, the mode of action of these two repair systems is similar, involving a cut-and-patch mechanism in which an oligonucleotide sequence containing the lesion is excised. The prokaryotic and eukaryotic NER damage-recognition factors have common structural features of β-hairpin intrusion between the two DNA strands at the site of the lesion. In the present study, we explored the hypothesis that this common β-hairpin intrusion motif is mirrored in parallel NER incision efficiencies in the two systems. We have utilized human HeLa cell extracts and the prokaryotic UvrABC proteins to determine their relative NER incision efficiencies. We report here comparisons of relative NER efficiencies with a set of stereoisomeric DNA lesions derived from metabolites of benzo[a]pyrene and equine estrogens in different sequence contexts, utilizing 21 samples. We found a general qualitative trend towards similar relative NER incision efficiencies for ~ 65% of these substrates; the other cases deviate mostly by ~ 30% or less from a perfect correlation, although several more distant outliers are also evident. This resemblance is consistent with the hypothesis that lesion recognition through β-hairpin insertion, a common feature of the two systems, is facilitated by local thermodynamic destabilization induced by the lesions in both cases. In the case of the UvrABC system, varying the nature of the UvrC endonuclease, while maintaining the same UvrA/B proteins, can markedly affect the relative incision efficiencies. These observations suggest that, in addition to recognition involving the initial modified duplexes, downstream events involving UvrC can also play a role in distinguishing and processing different lesions in prokaryotic NER. PMID:21741328

  16. ATR- and ATM-Mediated DNA Damage Response Is Dependent on Excision Repair Assembly during G1 but Not in S Phase of Cell Cycle.

    Science.gov (United States)

    Ray, Alo; Blevins, Chessica; Wani, Gulzar; Wani, Altaf A

    2016-01-01

    Cell cycle checkpoint is mediated by ATR and ATM kinases, as a prompt early response to a variety of DNA insults, and culminates in a highly orchestrated signal transduction cascade. Previously, we defined the regulatory role of nucleotide excision repair (NER) factors, DDB2 and XPC, in checkpoint and ATR/ATM-dependent repair pathway via ATR and ATM phosphorylation and recruitment to ultraviolet radiation (UVR)-induced damage sites. Here, we have dissected the molecular mechanisms of DDB2- and XPC- mediated regulation of ATR and ATM recruitment and activation upon UVR exposures. We show that the ATR and ATM activation and accumulation to UVR-induced damage not only depends on DDB2 and XPC, but also on the NER protein XPA, suggesting that the assembly of an active NER complex is essential for ATR and ATM recruitment. ATR and ATM localization and H2AX phosphorylation at the lesion sites occur as early as ten minutes in asynchronous as well as G1 arrested cells, showing that repair and checkpoint-mediated by ATR and ATM starts early upon UV irradiation. Moreover, our results demonstrated that ATR and ATM recruitment and H2AX phosphorylation are dependent on NER proteins in G1 phase, but not in S phase. We reasoned that in G1 the UVR-induced ssDNA gaps or processed ssDNA, and the bound NER complex promote ATR and ATM recruitment. In S phase, when the UV lesions result in stalled replication forks with long single-stranded DNA, ATR and ATM recruitment to these sites is regulated by different sets of proteins. Taken together, these results provide evidence that UVR-induced ATR and ATM recruitment and activation differ in G1 and S phases due to the existence of distinct types of DNA lesions, which promote assembly of different proteins involved in the process of DNA repair and checkpoint activation.

  17. A general role of the DNA glycosylase Nth1 in the abasic sites cleavage step of base excision repair in Schizosaccharomyces pombe.

    Science.gov (United States)

    Alseth, Ingrun; Korvald, Hanne; Osman, Fekret; Seeberg, Erling; Bjørås, Magnar

    2004-01-01

    One of the most frequent lesions formed in cellular DNA are abasic (apurinic/apyrimidinic, AP) sites that are both cytotoxic and mutagenic, and must be removed efficiently to maintain genetic stability. It is generally believed that the repair of AP sites is initiated by the AP endonucleases; however, an alternative pathway seems to prevail in Schizosaccharomyces pombe. A mutant lacking the DNA glycosylase/AP lyase Nth1 is very sensitive to the alkylating agent methyl methanesulfonate (MMS), suggesting a role for Nth1 in base excision repair (BER) of alkylation damage. Here, we have further evaluated the role of Nth1 and the second putative S.pombe AP endonuclease Apn2, in abasic site repair. The deletion of the apn2 open reading frame dramatically increased the sensitivity of the yeast cells to MMS, also demonstrating that the Apn2 has an important function in the BER pathway. The deletion of nth1 in the apn2 mutant strain partially relieves the MMS sensitivity of the apn2 single mutant, indicating that the Apn2 and Nth1 act in the same pathway for the repair of abasic sites. Analysis of the AP site cleavage in whole cell extracts of wild-type and mutant strains showed that the AP lyase activity of Nth1 represents the major AP site incision activity in vitro. Assays with DNA substrates containing base lesions removed by monofunctional DNA glycosylases Udg and MutY showed that Nth1 will also cleave the abasic sites formed by these enzymes and thus act downstream of these enzymes in the BER pathway. We suggest that the main function of Apn2 in BER is to remove the resulting 3'-blocking termini following AP lyase cleavage by Nth1.

  18. Importance of excision repair cross-complementation group 1 and ribonucleotide reductase M1 as prognostic biomarkers in malignant pleural mesothelioma treated with platinum-based induction chemotherapy followed by surgery.

    Science.gov (United States)

    Frischknecht, Lukas; Meerang, Mayura; Soltermann, Alex; Stahel, Rolf; Moch, Holger; Seifert, Burkhardt; Weder, Walter; Opitz, Isabelle

    2015-06-01

    Survival and response to platinum-based induction chemotherapy are heterogeneous among patients with malignant pleural mesothelioma. The aim of the present study was to assess the prognostic role of DNA repair markers, such as excision repair cross-complementation group 1 and ribonucleotide reductase M1, in multimodally treated patients with malignant pleural mesothelioma. Tumor tissue of a malignant pleural mesothelioma cohort (n = 107) treated with platinum/gemcitabine (n = 46) or platinum/pemetrexed (n = 61) induction chemotherapy followed by extrapleural pneumonectomy was assembled on a tissue microarray. Immunohistochemical expression of excision repair cross-complementation group 1 (nuclear) and ribonucleotide reductase M1 (nuclear and cytoplasmic) was assessed for its prognostic impact (association with overall survival or freedom from recurrence). Patients with high nuclear ribonucleotide reductase M1 expression before chemotherapy showed significantly longer freedom from recurrence (P = .03). When specifically analyzed in the subgroup of patients receiving platinum/gemcitabine followed by extrapleural pneumonectomy, high nuclear ribonucleotide reductase M1 was associated with prolonged freedom from recurrence (P = .03) and overall survival (P = .02). Low excision repair cross-complementation group 1 expression in prechemotherapy tumor tissues was associated with significantly longer freedom from recurrence (P = .04). Nuclear ribonucleotide reductase M1 and excision repair cross-complementation group 1 were independent prognosticators of freedom from recurrence in addition to pT stage in multivariate analysis. In the present study, nuclear ribonucleotide reductase M1 and excision repair cross-complementation group 1 expression were identified as independent prognosticators for freedom from recurrence of malignant pleural mesothelioma in patients undergoing induction chemotherapy followed by extrapleural pneumonectomy. Copyright © 2015 The American

  19. CARTILAGE CONSTRUCTS ENGINEERED FROM CHONDROCYTES OVEREXPRESSING IGF-I IMPROVE THE REPAIR OF OSTEOCHONDRAL DEFECTS IN A RABBIT MODEL

    Science.gov (United States)

    Madry, Henning; Kaul, Gunter; Zurakowski, David; Vunjak-Novakovic, Gordana; Cucchiarini, Magali

    2015-01-01

    Tissue engineering combined with gene therapy is a promising approach for promoting articular cartilage repair. Here, we tested the hypothesis that engineered cartilage with chondrocytes over expressing a human insulin-like growth factor I (IGF-I) gene can enhance the repair of osteochondral defects, in a manner dependent on the duration of cultivation. Genetically modified chondrocytes were cultured on biodegradable polyglycolic acid scaffolds in dynamic flow rotating bioreactors for either 10 or 28 d. The resulting cartilaginous constructs were implanted into osteochondral defects in rabbit knee joints. After 28 weeks of in vivo implantation, immunoreactivity to ß-gal was detectable in the repair tissue of defects that received lacZ constructs. Engineered cartilaginous constructs based on IGF-I-over expressing chondrocytes markedly improved osteochondral repair compared with control (lacZ) constructs. Moreover, IGF-I constructs cultivated for 28 d in vitro significantly promoted osteochondral repair vis-à-vis similar constructs cultivated for 10 d, leading to significantly decreased osteoarthritic changes in the cartilage adjacent to the defects. Hence, the combination of spatially defined overexpression of human IGF-I within a tissue-engineered construct and prolonged bioreactor cultivation resulted in most enhanced articular cartilage repair and reduction of osteoarthritic changes in the cartilage adjacent to the defect. Such genetically enhanced tissue engineering provides a versatile tool to evaluate potential therapeutic genes in vivo and to improve our comprehension of the development of the repair tissue within articular cartilage defects. Insights gained with additional exploration using this model may lead to more effective treatment options for acute cartilage defects. PMID:23588785

  20. Preoperative Botulinum toxin A enabling defect closure and laparoscopic repair of complex ventral hernia.

    Science.gov (United States)

    Rodriguez-Acevedo, Omar; Elstner, Kristen E; Jacombs, Anita S W; Read, John W; Martins, Rodrigo Tomazini; Arduini, Fernando; Wehrhahm, Michael; Craft, Colette; Cosman, Peter H; Dardano, Anthony N; Ibrahim, Nabeel

    2018-02-01

    Operative management of complex ventral hernia still remains a significant challenge for surgeons. Closure of large defects in the unprepared abdomen has serious pathophysiological consequences due to chronic contraction and retraction of the lateral abdominal wall muscles. We report outcomes of 56 consecutive patients who had preoperative Botulinum toxin A (BTA) abdominal wall relaxation facilitating closure and repair. This was a prospective observational study of 56 patients who underwent ultrasound-guided BTA into the lateral abdominal oblique muscles prior to elective ventral hernia repair between November 2012 and January 2017. Serial non-contrast abdominal CT imaging was performed to evaluate changes in lateral oblique muscle length and thickness. All hernias were repaired laparoscopically, or laparoscopic-open-laparoscopic (LOL) using intraperitoneal onlay mesh. 56 patients received BTA injections at predetermined sites to the lateral oblique muscles, which were well tolerated. Mean patient age was 59.7 years, and mean BMI was 30.9 kg/m 2 (range 21.8-54.0). Maximum defect size was 24 × 27 cm. A subset of 18 patients underwent preoperative pneumoperitoneum as an adjunct procedure. A comparison of pre-BTA to post-BTA imaging demonstrated an increase in mean lateral abdominal wall length from 16.1 cm to 20.1 cm per side, a mean gain of 4.0 cm/side (range 1.0-11.7 cm/side) (p LOL primary closure was achieved in all cases, with no clinical evidence of raised intra-abdominal pressures. One patient presented with a new fascial defect 26 months post-operative. Preoperative BTA to the lateral abdominal wall muscles is a safe and effective technique for the preparation of patients prior to operative management of complex ventral hernias. BTA temporary flaccid paralysis relaxes, elongates and thins the chronically contracted abdominal musculature. This in turn reduces lateral traction forces facilitating laparoscopic repair and fascial closure of large

  1. Frequent mismatch-repair defects link prostate cancer to Lynch syndrome

    DEFF Research Database (Denmark)

    Dominguez-Valentin, Mev; Joost, Patrick; Therkildsen, Christina

    2016-01-01

    BACKGROUND: A possible role for prostate cancer in Lynch syndrome has been debated based on observations of mismatch-repair defective tumors and reports of an increased risk of prostate cancer in mutation carriers. Potential inclusion of prostate cancer in the Lynch syndrome tumor spectrum...... is relevant for family classification, risk estimates and surveillance recommendations in mutation carriers. METHODS: We used the population-based Danish HNPCC-register to identify all prostate cancers that developed in mutation carriers and in their first-degree relatives from 288 Lynch syndrome families...... at age 70 was 3.7 % (95 % CI: 2.3-4.9). CONCLUSION: We provide evidence to link prostate cancer to Lynch syndrome through demonstration of MMR defective tumors and an increased risk of the disease, which suggests that prostate cancer should be considered in the diagnostic work-up of Lynch syndrome....

  2. Minimally Invasive Direct Repair of Bilateral Lumbar Spine Pars Defects in Athletes

    Directory of Open Access Journals (Sweden)

    Gabriel A. Widi

    2013-01-01

    Full Text Available Spondylolysis of the lumbar spine has traditionally been treated using a variety of techniques ranging from conservative care to fusion. Direct repair of the defect may be utilized in young adult patients without significant disc degeneration and lumbar instability. We used minimally invasive techniques to place pars interarticularis screws with the use of an intraoperative CT scanner in three young adults, including two athletes. This technique is a modification of the original procedure in 1970 by Buck, and it offers the advantage of minimal muscle dissection and optimal screw trajectory. There were no intra- or postoperative complications. The detailed operative procedure and the postoperative course along with a brief review of pars interarticularis defect treatment are discussed.

  3. Laparoscopic ventral hernia repair: outcomes in primary versus incisional hernias: no effect of defect closure.

    Science.gov (United States)

    Lambrecht, J R; Vaktskjold, A; Trondsen, E; Øyen, O M; Reiertsen, O

    2015-06-01

    Supposing divergent aetiology, we found it interesting to investigate outcomes between primary (PH) versus incisional (IH) hernias. In addition, we wanted to analyse the effect of defect closure and mesh fixation techniques. 37 patients with PH and 70 with IH were enrolled in a prospective cohort-study, treated with laparoscopic ventral hernia repair (LVHR) and randomised to ± transfascial sutures. In addition, we analysed results from a retrospective study with 36 PH and 51 IH patients. Mean follow-up time was 38 months in the prospective study and 27 months in the retrospective study. 35 % of PH's and 10 % of IH's were recurrences after previous suture repair. No late infections or mesh removals occurred. Recurrence rates in the prospective study were 0 vs. 4.3 % (p = 0.55) and the complication rates were 16 vs. 27 % (p = 0.24) in favour of the PH cohort. The IH group had a mesh protrusion rate of 13 vs. 5 % in the PH group (p = 0.32), and significantly (p hernias and adhesion score, longer operating time (100 vs. 79 min) and admission time (2.8 vs. 1.6 days). Closure of the hernia defect did not influence rate of seroma, pain at 2 months, protrusion or recurrence. An overall increased complication rate was seen after defect closure (OR 3.42; CI 1.25-9.33). With PH, in comparison to IH treated with LVHR, no differences were observed regarding recurrence, protrusion or complication rates. Defect closure (raphe), when using absorbable suture, did not benefit long-term outcomes and caused a higher overall complication rate. (ClinicalTrials.gov number: NCT00455299).

  4. Biomaterials with Antibacterial and Osteoinductive Properties to Repair Infected Bone Defects.

    Science.gov (United States)

    Lu, Haiping; Liu, Yi; Guo, Jing; Wu, Huiling; Wang, Jingxiao; Wu, Gang

    2016-03-03

    The repair of infected bone defects is still challenging in the fields of orthopedics, oral implantology and maxillofacial surgery. In these cases, the self-healing capacity of bone tissue can be significantly compromised by the large size of bone defects and the potential/active bacterial activity. Infected bone defects are conventionally treated by a systemic/local administration of antibiotics to control infection and a subsequent implantation of bone grafts, such as autografts and allografts. However, these treatment options are time-consuming and usually yield less optimal efficacy. To approach these problems, novel biomaterials with both antibacterial and osteoinductive properties have been developed. The antibacterial property can be conferred by antibiotics and other novel antibacterial biomaterials, such as silver nanoparticles. Bone morphogenetic proteins are used to functionalize the biomaterials with a potent osteoinductive property. By manipulating the carrying modes and release kinetics, these biomaterials are optimized to maximize their antibacterial and osteoinductive functions with minimized cytotoxicity. The findings, in the past decade, have shown a very promising application potential of the novel biomaterials with the dual functions in treating infected bone defects. In this review, we will summarize the current knowledge of novel biomaterials with both antibacterial and osteoinductive properties.

  5. Biomaterials with Antibacterial and Osteoinductive Properties to Repair Infected Bone Defects

    Science.gov (United States)

    Lu, Haiping; Liu, Yi; Guo, Jing; Wu, Huiling; Wang, Jingxiao; Wu, Gang

    2016-01-01

    The repair of infected bone defects is still challenging in the fields of orthopedics, oral implantology and maxillofacial surgery. In these cases, the self-healing capacity of bone tissue can be significantly compromised by the large size of bone defects and the potential/active bacterial activity. Infected bone defects are conventionally treated by a systemic/local administration of antibiotics to control infection and a subsequent implantation of bone grafts, such as autografts and allografts. However, these treatment options are time-consuming and usually yield less optimal efficacy. To approach these problems, novel biomaterials with both antibacterial and osteoinductive properties have been developed. The antibacterial property can be conferred by antibiotics and other novel antibacterial biomaterials, such as silver nanoparticles. Bone morphogenetic proteins are used to functionalize the biomaterials with a potent osteoinductive property. By manipulating the carrying modes and release kinetics, these biomaterials are optimized to maximize their antibacterial and osteoinductive functions with minimized cytotoxicity. The findings, in the past decade, have shown a very promising application potential of the novel biomaterials with the dual functions in treating infected bone defects. In this review, we will summarize the current knowledge of novel biomaterials with both antibacterial and osteoinductive properties. PMID:26950123

  6. Primary biventricular repair of atrioventricular septal defects: an analysis of reoperations.

    Science.gov (United States)

    Vohra, Hunaid A; Chia, Alicia X F; Yuen, Ho Ming; Vettukattil, Joseph J; Veldtman, Gruschen; Gnanapragasam, James; Roman, Kevin; Salmon, Anthony P; Haw, Marcus P

    2010-09-01

    The purpose of this study was to analyze the factors affecting reoperation after primary biventricular atrioventricular septal defect (AVSD) repair. Between April 1997 and April 2007, 93 consecutive patients underwent surgery for biventricular correction of AVSD with a median age of 5.8 months (range, 9 days to 68.9 years). Fifty-three patients had complete AVSD, 6 patients had an intermediate type, and 29 patients had partial AVSD; 4 patients had a complete AVSD with associated tetralogy of Fallot, and 1 patient had a complete AVSD with double-outlet right ventricle. There was no in-hospital mortality. There were 2 late deaths (2.2%). Forty-three reoperations were performed in 23 patients (24.7%), of which 18 were for repair of significant left atrioventricular valve regurgitation and 8 were mitral valve replacements. Seven patients (7.5%) required insertion of a permanent pacemaker. The overall 5-year freedom from reoperation after AVSD repair was 73.6% +/- 4.8%. In the multivariate analysis for complete AVSDs, Down syndrome (p = 0.01) and the presence of right ventricular dominance (p = 0.03) were independent predictors of reoperation. At last follow-up, 76 patients (83.5%) were in New York Heart Association class I, and 68 patients (74.7%) were not taking any heart failure medications. Echocardiographic examination showed absent to mild left atrioventricular valve regurgitation in 76.5%; moderate, in 19.8%; and severe, in 3.7% of patients. Down syndrome and right ventricular dominance are independent predictors of reoperation after complete AVSD repair. Biventricular repair of isolated AVSD with a small left ventricle can be successfully accomplished with no mortality. 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  7. Is the Oxidative DNA Damage Level of Human Lymphocyte Correlated with the Antioxidant Capacity of Serum or the Base Excision Repair Activity of Lymphocyte?

    Directory of Open Access Journals (Sweden)

    Yi-Chih Tsai

    2013-01-01

    Full Text Available A random screening of human blood samples from 24 individuals of nonsmoker was conducted to examine the correlation between the oxidative DNA damage level of lymphocytes and the antioxidant capacity of serum or the base excision repair (BER activity of lymphocytes. The oxidative DNA damage level was measured with comet assay containing Fpg/Endo III cleavage, and the BER activity was estimated with a modified comet assay including nuclear extract of lymphocytes for enzymatic cleavage. Antioxidant capacity was determined with trolox equivalent antioxidant capacity assay. We found that though the endogenous DNA oxidation levels varied among the individuals, each individual level appeared to be steady for at least 1 month. Our results indicate that the oxidative DNA damage level is insignificantly or weakly correlated with antioxidant capacity or BER activity, respectively. However, lymphocytes from carriers of Helicobacter pylori (HP or Hepatitis B virus (HBV tend to give higher levels of oxidative DNA damage (P<0.05. Though sera of this group of individuals show no particular tendency with reduced antioxidant capacity, the respective BER activities of lymphocytes are lower in average (P<0.05. Thus, reduction of repair activity may be associated with the genotoxic effect of HP or HBV infection.

  8. Resisting the Resistance in Cancer: Cheminformatics Studies on Short- Path Base Excision Repair Pathway Antagonists Using Supervised Learning Approaches.

    Science.gov (United States)

    Jain, Ritu; Jamal, Salma; Goyal, Sukriti; Wahi, Divya; Singh, Aditi; Grover, Abhinav

    2015-01-01

    Survival of cells and maintenance of genome depend on detection and repair of damaged DNA through intricate mechanisms. Cancer treatment relies on chemotherapy or radiation therapy that kills neoplastic cells by causing immense damage to the DNA. In many cases, escalated DNA repair mechanism leads to resistance against these therapies and therefore, there is a need to expand the interest in developing drugs that can sensitize the cells to such therapies by interfering with the DNA repair mechanism. Several studies have suggested a link between over expression of the primary mammalian enzyme, Apurinic/Apyrimidinic Endonuclease (APE1), responsible for abasic (or AP) site removal in the DNA and resistance of these cells to cancer therapy, whereas APE1 down-regulation sensitizes the cells to DNA damaging agents. Thus, the current treatment efficacy can be improved by aiding to selective sensitization of cancer cells and protection of normal cells. In the present study, we have used machine learning based approach by selecting assorted compounds with known activity for APE1 and constructed a range of in silico predictive classification models to discriminate between the inhibitors and non-inhibitors. These models can be applied to numerous other unscreened compounds to select the ones which are more likely to be the inhibitors for APE1. We have further found the common molecular substructures which were associated with the molecular activity of the compounds using a substructure search approach.

  9. 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.

  10. A child with xeroderma pigmentosum for excision of basal cell carcinoma

    OpenAIRE

    Mulimani, Sridevi M.; Talikoti, Dayanand G.

    2013-01-01

    Xeroderma pigmentosum (XP) is characterized by hypersensitivity to sunlight, ocular involvement, and progressive neurological complications. These manifestations are due to a cellular hypersensitivity to ultraviolet radiation leading to a defect in repair of DNA by the process of nucleotide excision repair. Basal cell carcinoma which is rare in children can occur with XP. Though the XP induced changes are predominately dermatologic, pose several challenges in anaesthetic management. Hence, we...

  11. Systematic review and meta-analysis of the repair of potentially contaminated and contaminated abdominal wall defects.

    Science.gov (United States)

    Atema, Jasper J; de Vries, Fleur E E; Boermeester, Marja A

    2016-11-01

    Repair of contaminated abdominal wall defects entails the dilemma of choosing between synthetic material, with its presumed risk of surgical site complications, and biologic material, a costly alternative with questionable durability. Thirty-two studies published between January 1990 and June 2015 on repair of (potentially) contaminated hernias with ≥25 patients were reviewed. Fifteen studies solely described hernia repair with biologic mesh, 6 nonabsorbable synthetic meshes, and 11 described various techniques. Surgical site complications and hernia recurrence rates were evaluated per degree of contamination and mesh type by calculating pooled proportions. Analysis showed no benefit of biologic over synthetic mesh for repair of potentially contaminated hernias with comparable surgical site complication rates and a hernia recurrence rate of 9% for biologic and 9% for synthetic repair. Biologic mesh repair of contaminated defects showed considerable higher rates of surgical site complications and a hernia recurrence rate of 30%. As only 1 study on synthetic repair of contaminated hernias was available, surgical decision making in the approach of contaminated abdominal wall defects is hampered. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Immune inhibition of repair of canine skull trephine defects implanted with partially purified bovine morphogenetic protein.

    Science.gov (United States)

    Nilsson, O S; Urist, M R

    1991-01-01

    The healing of 14-mm trephine skull defects was observed in ten adult mongrel dogs. First and second set trephine operations were performed to determine whether xenogeneic bovine bone morphogenetic protein (bBMP) and associated bone matrix water-insoluble noncollagenous proteins (iNCP) incite an immunological humoral response inhibiting bone repair. The effects of immunization to BMP/iNCP were observed by serum radioimmunoassay, and by correlated roentgenographic and histological analysis of deposits of new bone. The first set implants of bBMP/iNCP induced 96% healing while the regeneration of the second set trephines was 34% less than the first set. The second set was associated with a significant increase in serum anti-BMP antibodies. While xenogeneic bBMP induced complete healing of trephine defects when implanted without previous immunization, and repair in response to a second set of bBMP/iNCP was always incomplete, further research with high purified recombinant BMP is required to measure immune effects in a statistically significant number of pure bred recipients.

  13. A child with xeroderma pigmentosum for excision of basal cell carcinoma.

    Science.gov (United States)

    Mulimani, Sridevi M; Talikoti, Dayanand G

    2013-10-01

    Xeroderma pigmentosum (XP) is characterized by hypersensitivity to sunlight, ocular involvement, and progressive neurological complications. These manifestations are due to a cellular hypersensitivity to ultraviolet radiation leading to a defect in repair of DNA by the process of nucleotide excision repair. Basal cell carcinoma which is rare in children can occur with XP. Though the XP induced changes are predominately dermatologic, pose several challenges in anaesthetic management. Hence, we are reporting a 9-year-old child with XP scheduled for excision of basal cell carcinoma under general anaesthesia.

  14. A child with xeroderma pigmentosum for excision of basal cell carcinoma

    Directory of Open Access Journals (Sweden)

    Sridevi M Mulimani

    2013-01-01

    Full Text Available Xeroderma pigmentosum (XP is characterized by hypersensitivity to sunlight, ocular involvement, and progressive neurological complications. These manifestations are due to a cellular hypersensitivity to ultraviolet radiation leading to a defect in repair of DNA by the process of nucleotide excision repair. Basal cell carcinoma which is rare in children can occur with XP. Though the XP induced changes are predominately dermatologic, pose several challenges in anaesthetic management. Hence, we are reporting a 9-year-old child with XP scheduled for excision of basal cell carcinoma under general anaesthesia.

  15. TissuePatch™ as a novel synthetic sealant for repair of superficial lung defect: in vitro tests results.

    Science.gov (United States)

    Zhang, Ruoyu; Bures, Maximilian; Höffler, Hans-Klaus; Zinne, Norman; Länger, Florian; Bisdas, Theodosios; Haverich, Axel; Krüger, Marcus

    2012-11-19

    Controversies surrounding the efficacy of surgical sealants against alveolar air leaks (AAL) in lung surgery abound in the literature. We sought to test the sealing efficacy of a novel synthetic sealant, TissuePatch™ in an in vitro lung model. The lower lobe of freshly excised swine lung (n = 10) was intubated and ventilated. A superficial parenchymal defect (40 × 25 mm) was created, followed by AAL assessment. After sealant application, AAL was assessed again until burst failure occurred. The length of defect was recorded to evaluate the elasticity of the sealant. Superficial parenchymal defects resulted in AAL increasing disproportionally with ascending maximal inspiratory pressure (Pmax). Multiple linear regression analysis revealed strong correlation between AAL and Pmax, compliance, resistance. After sealant application, AAL was sealed in all ten tests at an inspired tidal volume (TVi) of 400 ml, in nine tests at TVi = 500 ml, in seven at TVi = 600 ml and in five at TVi = 700 ml. The mean burst pressure was 42 ± 9 mBar. Adhesive and cohesive sealant failures were found in six and three tests respectively. The length of defect before sealant failure was 8.9 ± 4.9% larger than that at TVi = 400 ml, demonstrating an adequate elasticity of this sealant film. TissuePatch™ may be a reliable sealant for alternative or adjunctive treatment for repair of superficial parenchymal defects in lung surgery. The clinical benefits of this sealant should be confirmed by prospective, randomised controlled clinical trials. ABSTRAKT: Die Wirksamkeit von chirurgischen Klebstoffen zur Prävention von alveolo-pleuralem Luftleck (APL) ist trotz zunehmenden klinischen Anwendungen in Lungenchirurgie immer noch kontrovers diskutiert. Wir evaluierten die Abdichtungswirksamkeit von einem neuartigen synthetischen Kleber, TissuePatch™ mittels eines in vitro Lungenmodels. METHODE: Der Unterlappen von frisch entnommenen Schweinlungen (n = 10) wurde

  16. Distal Inside-Out Epineural Sliding Technique to Repair Segmental Nerve Defects.

    Science.gov (United States)

    Luokkala, Toni; Ryhänen, Jorma; Näpänkangas, Juha; Karjalainen, Teemu V

    2016-09-01

    Background: The repair of a segmental peripheral nerve injury is a clinical challenge. Several studies have been performed to determine superior methods for overcoming nerve gaps. The purpose of this study was to investigate if the inside-out slided epineurium of the distal segment of an injured nerve can serve as a conduit to bridge a short nerve defect (10 mm). Methods: Nineteen sciatic nerves in Sprague-Dawley rats were transected, and a 10-mm gap was left between the ends. A section of distal epineurium was pulled inside out to bridge the gap. Walking track analysis was performed, and the sciatic function index (SFI) was calculated. Wet muscle mass and withdrawal reflex were measured. The density of axon fibers at different levels of repaired nerves was determined, and histological analysis was performed at 16 weeks. Results: The mean SFI improved from -81.0 at 4 weeks to 36.3 at 16 weeks. The axon densities showed regeneration through the epineural tube, and 5 of the rats demonstrated a withdrawal reflex. The weight of the tibialis anterior muscle of the injured limb at 16 weeks was 59% that of the uninjured side. Conclusions: The distal epineural sheath tube provided a size-matched conduit between the nerve stumps, with no histological donor-site morbidity. Histologically, regeneration occurred through the epineural tube without neuroma formation, and functional recovery was comparable to that of previous studies of nerve repair techniques. Technique may be an addition to the armamentarium of tools used to treat segmental nerve defects.

  17. Efficacy of a novel IGS system in atrial septal defect repair

    Science.gov (United States)

    Mefleh, Fuad N.; Baker, G. Hamilton; Kwartowitz, David M.

    2013-03-01

    Congenital heart disease occurs in 107.6 out of 10,000 live births, with Atrial Septal Defects (ASD) accounting for 10% of these conditions. Historically, ASDs were treated with open heart surgery using cardiopulmonary bypass, allowing a patch to be sewn over the defect. In 1976, King et al. demonstrated use of a transcatheter occlusion procedure, thus reducing the invasiveness of ASD repair. Localization during these catheter based procedures traditionally has relied on bi-plane fluoroscopy; more recently trans-esophageal echocardiography (TEE) and intra-cardiac echocardiography (ICE) have been used to navigate these procedures. Although there is a high success rate using the transcatheter occlusion procedure, fluoroscopy poses radiation dose risk to both patient and clinician. The impact of this dose to the patients is important as many of those undergoing this procedure are children, who have an increased risk associated with radiation exposure. Their longer life expectancy than adults provides a larger window of opportunity for expressing the damaging effects of ionizing radiation. In addition, epidemiologic studies of exposed populations have demonstrated that children are considerably more sensitive to the carcinogenic effects radiation. Image-guided surgery (IGS) uses pre-operative and intra-operative images to guide surgery or an interventional procedure. Central to every IGS system is a software application capable of processing and displaying patient images, registration between multiple coordinate systems, and interfacing with a tool tracking system. We have developed a novel image-guided surgery framework called Kit for Navigation by Image Focused Exploration (KNIFE). In this work we assess the efficacy of this image-guided navigation system for ASD repair using a series of mock clinical experiments designed to simulate ASD repair device deployment.

  18. Repair of double outlet right ventricle with doubly-committed ventricular septal defect.

    Science.gov (United States)

    Uemura, H; Yagihara, T; Kadohama, T; Kawahira, Y; Yoshikawa, Y

    2001-07-01

    To investigate our surgical results of intraventricular rerouting in patients having double outlet right ventricle with doubly-committed ventricular septal defect. We undertook repair in 8 patients with this particular feature. Of these, 2 patients had pulmonary stenosis, and another had interruption of the aortic arch. The subarterial defect was unequivocally related to both the aortic and the-pulmonary orifices in all, albeit slightly deviated towards the aortic orifice in one, and towards the pulmonary orifice in another. Intraventricular rerouting was carried out via incisions to the right atrium and the pulmonary trunk. To ensure reconstruction of an unobstructed pulmonary pathway, a limited right ventriculotomy was made in 5. All patients survived the procedure, and are currently doing well, with follow-up of 25 to 194 months, with a mean of 117+/-68 months. Catheterization carried out 16+/-6 months after repair demonstrated excellent ventricular parameters. Mean pulmonary arterial pressure was 16+/-7 mmHg, being higher than 20 mmHg in 2 patients. No significant obstruction was found between the right ventricle and the pulmonary arteries. A pressure gradient across the left ventricular outflow tract became significant in one patient in whom a small outlet septum was present, and a heart-shaped baffle had been used for intraventricular rerouting. Reoperation was eventually needed in this patient for treatment of the obstruction, which proved to be progressive. Precise recognition of the morphologic features is of paramount importance when choosing the optimal options for biventricular repair in patients with double outlet right ventricle and doubly-committed interventricular communication.

  19. Custom Repair of Mandibular Bone Defects with 3D Printed Bioceramic Scaffolds.

    Science.gov (United States)

    Shao, H; Sun, M; Zhang, F; Liu, A; He, Y; Fu, J; Yang, X; Wang, H; Gou, Z

    2018-01-01

    Implanting artificial biomaterial implants into alveolar bone defects with individual shape and appropriate mechanical strength is still a challenge. In this study, bioceramic scaffolds, which can precisely match the mandibular defects in macro and micro, were manufactured by the 3-dimensional (3D) printing technique according to the computed tomography (CT) image. To evaluate the stimulatory effect of the material substrate on bone tissue regeneration in situ in a rabbit mandibular alveolar bone defect model, implants made with the newly developed, mechanically strong ~10% Mg-substituted wollastonite (Ca90%Mg10%SiO3; CSi-Mg10) were fabricated, implanted into the bone defects, and compared with implants made with the typical Ca-phosphate and Ca-silicate porous bioceramics, such as β-tricalcium phosphate (TCP), wollastonite (CaSiO3; CSi), and bredigite (Bred). The initial physicochemical tests indicated that although the CSi-Mg10 scaffolds had the largest pore dimension, they had the lowest porosity mainly due to the significant linear shrinkage of the scaffolds during sintering. Compared with the sparingly dissolvable TCP scaffolds (~2% weight loss) and superfast dissolvable (in Tris buffer within 6 wk) pure CSi and Bred scaffolds (~12% and ~14% weight loss, respectively), the CSi-Mg10 exhibited a mild in vitro biodissolution and moderate weight loss of ~7%. In addition, the CSi-Mg10 scaffolds showed a considerable initial flexural strength (31 MPa) and maintained very high flexural resistance during soaking in Tris buffer. The in vivo results revealed that the CSi-Mg10 scaffolds have markedly higher osteogenic capability than those on the TCP, CSi, and Bred scaffolds after 16 wk. These results suggest a promising potential application of customized CSi-Mg10 3D robocast scaffolds in the clinic, especially for repair of alveolar bone defects.

  20. Monte Carlo simulation of base and nucleotide excision repair of clustered DNA damage sites. I. Model properties and predicted trends

    Energy Technology Data Exchange (ETDEWEB)

    Semenenko, Vladimir; Stewart, Robert D.; Ackerman, Eric J.

    2005-12-31

    Single-cell irradiators and new experimental assays are rapidly expanding our ability to quantify the molecular mechanisms responsible for phenomena such as toxicant-induced adaptations in DNA repair and signal-mediated changes to the genome stability of cells not directly damaged by radiation (i.e., bystander cells). To advance our understanding of, and ability to predict and mitigate, the potentially harmful effects of radiological agents, effective strategies must be devised to incorporate information from molecular and cellular studies into mechanism-based, hierarchical models. A key advantage of the hierarchical modeling approach is that information from DNA repair and other in vitro assays can be systematically integrated into higher-level cell transformation and, eventually, carcinogenesis models. This presentation will outline the hierarchical modeling strategy used to integrate information from in vitro studies into the Virtual Cell (VC) radiobiology software (see Endnote). A new multi-path genomic instability model will be introduced and used to link biochemical processing of double strand breaks (DSBs) to neoplastic cell transformation. Bystander and directly damaged cells are treated explicitly in the model using a microdosimetric approach, although many of the details of the bystander response model are of a necessarily preliminary nature. The new model will be tested against several published radiobiological datasets. Results illustrating how hypothesized bystander mechanisms affect the shape of dose-response curves for neoplastic transformation as a function of Linear Energy Transfer (LET) will be presented. EndNote: R.D. Stewart, Virtual Cell (VC) Radiobiology Software. PNNL-13579, July 2001. Available at http://www.pnl.gov/berc/kbem/vc/ The DNA repair model used in the VC computer program is based on the Two-Lesion Kinetic (TLK) model [Radiat. Res. 156(4), 365-378 October 2001].

  1. Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair

    DEFF Research Database (Denmark)

    Akbari, Mansour; Keijzers, Guido; Maynard, Scott

    2014-01-01

    slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I...... by rotenone. Our results suggest that the amount of DNA ligase III in mitochondria may be critical for cell survival following prolonged oxidative stress, and demonstrate a functional link between mitochondrial DNA damage and repair, cell survival upon oxidative stress, and removal of dysfunctional...

  2. Induction of base excision repair enzymes NTH1 and APE1 in rat spleen following aniline exposure.

    Science.gov (United States)

    Ma, Huaxian; Wang, Jianling; Abdel-Rahman, Sherif Z; Boor, Paul J; Khan, M Firoze

    2013-03-15

    Mechanisms by which aniline exposure elicits splenotoxicity, especially a tumorigenic response, are not well-understood. Earlier, we have shown that aniline exposure leads to oxidative DNA damage and up-regulation of OGG1 and NEIL1/2 DNA glycosylases in rat spleen. However, the contribution of endonuclease III homolog 1 (NTH1) and apurinic/apyrimidinic endonuclease 1 (APE1) in the repair of aniline-induced oxidative DNA damage in the spleen is not known. This study was, therefore, focused on examining whether NTH1 and APE1 contribute to the repair of oxidative DNA lesions in the spleen, in an experimental condition preceding tumorigenesis. To achieve this, male SD rats were subchronically exposed to aniline (0.5 mmol/kg/day via drinking water for 30 days), while controls received drinking water only. By quantitating the cleavage products, the activities of NTH1 and APE1 were assayed using substrates containing thymine glycol (Tg) and tetrahydrofuran, respectively. Aniline treatment led to significant increases in NTH1- and APE1-mediated BER activity in the nuclear extracts of spleen of aniline-treated rats compared to the controls. NTH1 and APE1 mRNA expression in the spleen showed 2.9- and 3.2-fold increases, respectively, in aniline-treated rats compared to the controls. Likewise, Western blot analysis showed that protein expression of NTH1 and APE1 in the nuclear extracts of spleen from aniline-treated rats was 1.9- and 2.7-fold higher than the controls, respectively. Immunohistochemistry indicated that aniline treatment also led to stronger immunoreactivity for both NTH1 and APE1 in the spleens, confined to the red pulp areas. These results, thus, show that aniline exposure is associated with induction of NTH1 and APE1 in the spleen. The increased repair activity of NTH1 and APE1 could be an important mechanism for the removal of oxidative DNA lesions. These findings thus identify a novel mechanism through which NTH1 and APE1 may regulate the repair of

  3. Clinical Evaluations of Soft and Hard Tissue Repair Using Osteo Gen in Periodontal Intraosseous Defects

    Directory of Open Access Journals (Sweden)

    Haghighati F

    2000-05-01

    Full Text Available The aim of this study was to evaluate the repair of hard and soft tissue using Osteo Gen and"ncomparing with flap curettage in periodontal defects. 36 periodontal intraosseous defects in sixteen"npatients involved moderate to advanced periodontitis were randomly selected and allocated to two"ngroups: test (22 and control groups (14. Slow resorption, excellent tissue compatibility, no exfoliation"nand root resorption were considered during healing. The average of pocket depth in test and control"ngroups was 3.16 and 2.73 mm, respectively. After 6 months, the average of bone repair was 2.18 mm"n(68.97% and 0.46 mm (16.84% in test and control groups. Bone apposition was obtained in test group"n(0.09 mm (2.84% while bone loss observed in control group (0.32 mm(l 1.72%. Initial pocket depths"nin test and control groups were 7.68mm and 6.61mm. After six months, re-entry surgery was performed"nand the measurement of new attachment was 3.45 mm (61.19% and 2.81 mm (51.28%. Recession of"nthe gingival margin was 1.22 mm (15.80% and 0,58 mm (8.77% for test and control groups,"nrespectively. By considering these findings, using of Osteo Gen can be recommended compare with flap"ncurettage in periodontal intraosseous defects.

  4. Technical Report: Correlation Between the Repair of Cartilage and Subchondral Bone in an Osteochondral Defect Using Bilayered, Biodegradable Hydrogel Composites.

    Science.gov (United States)

    Lu, Steven; Lam, Johnny; Trachtenberg, Jordan E; Lee, Esther J; Seyednejad, Hajar; van den Beucken, Jeroen J J P; Tabata, Yasuhiko; Kasper, F Kurtis; Scott, David W; Wong, Mark E; Jansen, John A; Mikos, Antonios G

    2015-12-01

    The present work investigated correlations between cartilage and subchondral bone repair, facilitated by a growth factor-delivering scaffold, in a rabbit osteochondral defect model. Histological scoring indices and microcomputed tomography morphological parameters were used to evaluate cartilage and bone repair, respectively, at 6 and 12 weeks. Correlation analysis revealed significant associations between specific cartilage indices and subchondral bone parameters that varied with location in the defect (cortical vs. trabecular region), time point (6 vs. 12 weeks), and experimental group (insulin-like growth factor-1 only, bone morphogenetic protein-2 only, or both growth factors). In particular, significant correlations consistently existed between cartilage surface regularity and bone quantity parameters. Overall, correlation analysis between cartilage and bone repair provided a fuller understanding of osteochondral repair and can help drive informed studies for future osteochondral regeneration strategies.

  5. Development of new nerve guide tube for repair of long nerve defects.

    Science.gov (United States)

    Ichihara, Satoshi; Inada, Yuji; Nakada, Akira; Endo, Katsuaki; Azuma, Takashi; Nakai, Ryusuke; Tsutsumi, Sadami; Kurosawa, Hisashi; Nakamura, Tatsuo

    2009-09-01

    A novel nerve guide tube (poly (L-lactic) acid (PLLA)/ polyglycolic acid (PGA)-c-tube) capable of repairing long peripheral nerve injuries in a canine model has been developed. The tube was created by braiding together PLLA and PGA and then coating it with collagen. PLLA was newly added to the formulation to achieve higher sustainability. The tube was compared with a PGA-collagen tube in clinical use since 2002 having the same structure with a collagen coating but composed of PGA alone (PGA-c-tube). When tested for repair of a 40-mm gap in the left peroneal nerve, using PLLA/PGA-c-tube (n = 15), PGA-c-tube (n = 15), and a negative control group where the cut stump was capped using a silicone cap (n = 15), the lumen structure essential for securing the space for nerve regeneration was maintained in PLLA/PGA-c-tube for over 12 months with a higher number of axons both within the tube and at the distal nerve end. Electrophysiological evaluation revealed that the amplitude of compound muscle action potentials and sensory nerve action potentials after nerve regeneration with PLLA/PGA-c-tube were significantly higher. When assessed using magnetic resonance imaging (MRI), the volume of the tibialis anterior (TA) muscle in dogs that had undergone nerve repair using PLLA/PGA-c-tube was approximately 80% that of the positive control at 12 months. Functional analysis conducted by assessing the ankle angle revealed faster recovery in the PLLA/PGA-c-tube group. Better regeneration was achieved using a PLLA/PGA-c-tube that contains the slowly decomposing fiber material, PLLA. This indicates potential for repair of even longer nerve gaps or defects located near joints, and also clinical application.

  6. Tricuspid valve mycetoma in an infant successfully treated by excision and complex tricuspid valve repair followed by fluconazole therapy.

    Science.gov (United States)

    Anil Kumar, V; Francis, Edwin; Sreehari, Sreekala; Raj, Benedict

    2014-04-01

    Fungal valve endocarditis in children is an uncommon and lethal disease. The risk increases with use of central venous catheters (CVC), total parenteral nutrition (TPN), and use of broad-spectrum antibiotics during the neonatal period. Due to high mortality, a combination of surgery and antifungal therapy is usually recommended for treatment. Case report and review of the literature. We present a case of an asymptomatic infant with multiple Candida tricuspid valve mycetomas. Complete cure was achieved by combined tricuspid valve repair and fluconazole therapy. We also review 26 cases of tricuspid valve Candida endocarditis in children published in the literature. From being uniformly fatal five decades ago to a current survival rate of 64% to 100%, the prognosis of Candida endocarditis has changed dramatically with the use of antifungal therapy alone or in combination with surgery. Our case re-emphasizes the role of valve-sparing debridement with repair of the native valve using autologous pericardium in combination with long-term antifungal therapy as a feasible option in managing tricuspid valve Candida endocarditis.

  7. [Repair of soft tissue defect in hand or foot with lobulated medial sural artery perforator flap].

    Science.gov (United States)

    Fengjing, Zhao; Jianmin, Yao; Xingqun, Zhang; Liang, Ma; Longchun, Zhang; Yibo, Xu; Peng, Wang; Zhen, Zhu

    2015-11-01

    To explore the clinical effect of the lobulated medial sural artery perforator flap in repairing soft tissue defect in hand or foot. Since March 2012 to September 2014, 6 cases with soft tissue defects in hands or feet were treated by lobulated medial sural artery flaps pedicled with 1st musculo-cutaneous perforator and 2st musculo-cutaneous perforator of the medial sural artery. The size of the flaps ranged from 4.5 cm x 10.0 cm to 6.0 cm x 17.0 cm. 5 cases of lobulated flap survived smoothly, only 1 lobulated flap had venous articulo, but this flap also survived after the articulo was removed by vascular exploration. All flaps had desirable appearance and sensation and the two-point discrimination was 6 mm in mean with 4 to 12 months follow-up (average, 7 months). Linear scar was left in donor sites in 3 cases and skin scar in 3 cases. There was no malfunction in donor sites. Lobulated medial sural artery perforator flap is feasible and ideal method for the treatment of soft tissue defect in hand or foot with satisfactory effect.

  8. Low frequency of defective mismatch repair in a population-based series of upper urothelial carcinoma

    Directory of Open Access Journals (Sweden)

    Isfoss Björn L

    2005-03-01

    Full Text Available Abstract Background Upper urothelial cancer (UUC, i.e. transitional cell carcinomas of the renal pelvis and the ureter, occur at an increased frequency in patients with hereditary nonpolyposis colorectal cancer (HNPCC. Defective mismatch repair (MMR specifically characterizes HNPCC-associated tumors, but also occurs in subsets of some sporadic tumors, e.g. in gastrointestinal cancer and endometrial cancer. Methods We assessed the contribution of defective MMR to the development of UUC in a population-based series from the southern Swedish Cancer Registry, through microsatellite instability (MSI analysis and immunohistochemical evaluation of expression of the MMR proteins MLH1, PMS2, MSH2, and MSH6. Results A MSI-high phenotype was identified in 9/216 (4% successfully analyzed patients and a MSI-low phenotype in 5/216 (2%. Loss of MMR protein immunostaining was found in 11/216 (5% tumors, and affected most commonly MSH2 and MSH6. Conclusion This population-based series indicates that somatic MMR inactivation is a minor pathway in the development of UUC, but tumors that display defective MMR are, based on the immunohistochemical expression pattern, likely to be associated with HNPCC.

  9. Energy and Technology Review: Unlocking the mysteries of DNA repair

    Energy Technology Data Exchange (ETDEWEB)

    Quirk, W.A.

    1993-04-01

    DNA, the genetic blueprint, has the remarkable property of encoding its own repair following diverse types of structural damage induced by external agents or normal metabolism. We are studying the interplay of DNA damaging agents, repair genes, and their protein products to decipher the complex biochemical pathways that mediate such repair. Our research focuses on repair processes that correct DNA damage produced by chemical mutagens and radiation, both ionizing and ultraviolet. The most important type of DNA repair in human cells is called excision repair. This multistep process removes damaged or inappropriate pieces of DNA -- often as a string of 29 nucleotides containing the damage -- and replaces them with intact ones. We have isolated, cloned, and mapped several human repair genes associated with the nucleotide excision repair pathway and involved in the repair of DNA damage after exposure to ultraviolet light or mutagens in cooked food. We have shown that a defect in one of these repair genes, ERCC2, is responsible for the repair deficiency in one of the groups of patients with the recessive genetic disorder xeroderma pigmentosum (XP group D). We are exploring ways to purify sufficient quantities (milligrams) of the protein products of these and other repair genes so that we can understand their functions. Our long-term goals are to link defective repair proteins to human DNA repair disorders that predispose to cancer, and to produce DNA-repair-deficient mice that can serve as models for the human disorders.

  10. Direct Repair of Lumbar Pars Interarticularis Defects by Utilizing Intraoperative O-Arm-Based Navigation and Microendoscopic Techniques.

    Science.gov (United States)

    Jia, Min; Wang, Jian; Zhang, Zhengfeng; Zheng, Wenjie; Zhou, Yue

    2016-10-01

    A retrospective analysis of the clinical outcomes of eight patients with the lumbar pars interarticulars defects treated by direct repair with the aid of intraoperative O-arm based navigation and microendoscopic techniques. The aim of this study was to investigate the efficacy and safety of direct screw repair by using minimally invasive surgery for the lumbar pars interarticulars defects in a pilot study. Direct repair of pars interarticulars defects has been used to treat young adult patients. Reports concerning direct repair by minimally invasive techniques for pars interarticulars defects are quite rare. Review of medical records identified eight consecutive patients treated with intraoperative O-arm based navigation and microendoscopic techniques. Debridement and autograft of pars interarticularis defects was performed under microendoscopic procedure. Then, percutaneous bilateral intralaminar screws were inserted by utilizing intraoperative navigation. The clinical and radiological data were collected and analyzed retrospectively. Eight patients had a mean age of 28.4 years, and five were 30 years or younger at the time of treatment. Symptoms included axial back pain in 100% of patients without concomitant radiculopathy. Autograft was used in all cases. The average follow-up duration was 27.4 months with a range of 20 to 33 months. Symptoms resolved completely or partially in all patients. Low back pain visual analog scores decrease from preoperative 6.8 to postoperative 1.4 of eight cases. Of 16 pars defects, healing was observed in 13 (81.3%) at last radiological follow-up. One patient with bilateral fusion failure refused revision surgery because of mild complaint. No complications such as dural tear, nerve root injury, and infection occurred. Minimally invasive direct repair of the pars interarticularis defects with intralaminar screws by using microendoscopic system and navigation procedure can provide safe and effective treatment of spondylolysis with

  11. The Effect of Sodium Hyaluronate on Ligamentation and Biomechanical Property of Tendon in Repair of Achilles Tendon Defect with Polyethylene Terephthalate Artificial Ligament: A Rabbit Tendon Repair Model.

    Science.gov (United States)

    Li, Shengkun; Ma, Kui; Li, Hong; Jiang, Jia; Chen, Shiyi

    2016-01-01

    The Achilles tendon is the most common ruptured tendon of human body. Reconstruction with polyethylene terephthalate (PET) artificial ligament is recommended in some serious cases. Sodium hyaluronate (HA) is beneficial for the healing of tendon injuries. We aimed to determine the effect of sodium hyaluronate in repair of Achilles tendon defect with PET artificial ligament in an animal tendon repair model. Sixteen New Zealand White rabbits were divided into two groups. Eight rabbits repaired with PET were assigned to PET group; the other eight rabbits repaired with PET along with injection of HE were assigned to HA-PET group. All rabbits were sacrificed at 4 and 8 weeks postoperatively for biomechanical and histological examination. The HA-PET group revealed higher biomechanical property compared with the PET group. Histologically, more collagen tissues grew into the HA-PET group compared with PET group. In conclusion, application of sodium hyaluronate can improve the healing of Achilles tendon reconstruction with polyethylene terephthalate artificial ligament.

  12. Mineralization Induction of Gingival Fibroblasts and Construction of a Sandwich Tissue-Engineered Complex for Repairing Periodontal Defects.

    Science.gov (United States)

    Wu, Mingxuan; Wang, Jie; Zhang, Yanning; Liu, Huijuan; Dong, Fusheng

    2018-02-22

    BACKGROUND The ideal healing technique for periodontal tissue defects would involve the functional regeneration of the alveolar bone, cementum, and periodontal ligament, with new periodontal attachment formation. In this study, gingival fibroblasts were induced and a "sandwich" tissue-engineered complex (a tissue-engineered periodontal membrane between 2 tissue-engineered mineralized membranes) was constructed to repair periodontal defects. We evaluated the effects of gingival fibroblasts used as seed cells on the repair of periodontal defects and periodontal regeneration. MATERIAL AND METHODS Primitively cultured gingival fibroblasts were seeded bilaterally on Bio-Gide collagen membrane (a tissue-engineered periodontal membrane) or unilaterally on small intestinal submucosa segments, and their mineralization was induced. A tissue-engineered sandwich was constructed, comprising the tissue-engineered periodontal membrane flanked by 2 mineralized membranes. Periodontal defects in premolar regions of Beagles were repaired using the tissue-engineered sandwich or periodontal membranes. Periodontal reconstruction was compared to normal and trauma controls 10 or 20 days postoperatively. RESULTS Periodontal defects were completely repaired by the sandwich tissue-engineered complex, with intact new alveolar bone and cementum, and a new periodontal ligament, 10 days postoperatively. CONCLUSIONS The sandwich tissue-engineered complex can achieve ideal periodontal reconstruction rapidly.

  13. DNA excision repair and double-strand break repair gene polymorphisms and the level of chromosome aberration in children with long-term exposure to radon.

    Science.gov (United States)

    Larionov, Aleksey V; Sinitsky, Maxim Y; Druzhinin, Vladimir G; Volobaev, Valentin P; Minina, Varvara I; Asanov, Maxim A; Meyer, Alina V; Tolochko, Tatiana A; Kalyuzhnaya, Ekaterina E

    2016-08-01

    To study polymorphic variants of repair genes in people affected by long-term exposure to radon. The chromosome aberration frequency in peripheral blood lymphocytes was used as the biological marker of genotoxicity. Genotyping of 12 single nucleotide polymorphisms in DNA repair genes (APE, XRCC1, OGG1, ADPRT, XpC, XpD, XpG, Lig4 and NBS1) was performed in children with long-term resident exposure to radon. Quantification of the aberrations was performed using light microscopy. The total frequency of aberrations was increased in carriers of the G/G genotype for the XpD gene (rs13181) polymorphism in recessive model confirmed by the results of ROC-analysis ('satisfactory predictor', AUC = 0.609). Single chromosome fragments frequency was increased in carriers of the G/G genotype in comparison with the T/T genotype. In respect to the total frequency of aberrations, the G/G genotype for the XpG gene (rs17655) polymorphism was also identified as a 'satisfactory predictor' (AUC = 0.605). Carriers of the T/C genotype for the ADPRT gene (rs1136410) polymorphism were characterized by an increased level of single fragments relative to the T/T genotype. The relationships with several types of cytogenetic damage suggest these three SNP (rs13181, rs17655 and rs1136410) may be considered radiosensitivity markers.

  14. 59. Early and late results of routine leaflet augmentation for complete atrio-ventricular septal defect repair

    OpenAIRE

    A. Arifi; Najm, H; Khan, A.; Ahmad, M; Khan, M A; M. Elanany

    2016-01-01

    Complete AVSD (CAVSD) is characterized by the presence of a common atrio-ventricular (AV) orifice, an inter-atrial communication, and a ventricular septal defect (VSD). Results of surgical correction of atrio-ventricular septal defects (AVSDs) have improved over the last decades; however, the need for reoperation for left atrio-ventricular valve regurgitation, after primary AVSD repair remains a major concern. The aim of our study is to assess the outcome of the routine leaflet augmentation t...

  15. Evidence for a repair enzyme complex involving ERCC1, and the correcting activities of ERCC4, ERCC11 and the xeroderma pigmentosum group F.

    NARCIS (Netherlands)

    A.J. van Vuuren (Hanneke); E. Appeldoorn (Esther); H. Odijk (Hanny); A. Yasui (Akira); N.G.J. Jaspers (Nicolaas); D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1993-01-01

    textabstractNucleotide excision repair (NER), one of the major cellular DNA repair systems, removes a wide range of lesions in a multi-enzyme reaction. In man, a NER defect due to a mutation in one of at least 11 distinct genes, can give rise to the inherited repair disorders xeroderma pigmentosum

  16. Defective Bone Repair in C57Bl6 Mice With Acute Systemic Inflammation.

    Science.gov (United States)

    Behrends, D A; Hui, D; Gao, C; Awlia, A; Al-Saran, Y; Li, A; Henderson, J E; Martineau, P A

    2017-03-01

    Bone repair is initiated with a local inflammatory response to injury. The presence of systemic inflammation impairs bone healing and often leads to malunion, although the underlying mechanisms remain poorly defined. Our research objective was to use a mouse model of cortical bone repair to determine the effect of systemic inflammation on cells in the bone healing microenvironment. QUESTION/PURPOSES: (1) Does systemic inflammation, induced by lipopolysaccharide (LPS) administration affect the quantity and quality of regenerating bone in primary bone healing? (2) Does systemic inflammation alter vascularization and the number or activity of inflammatory cells, osteoblasts, and osteoclasts in the bone healing microenvironment? Cortical defects were drilled in the femoral diaphysis of female and male C57BL/6 mice aged 5 to 9 months that were treated with daily systemic injections of LPS or physiologic saline as control for 7 days. Mice were euthanized at 1 week (Control, n = 7; LPS, n = 8), 2 weeks (Control, n = 7; LPS, n = 8), and 6 weeks (Control, n = 9; LPS, n = 8) after surgery. The quantity (bone volume per tissue volume [BV/TV]) and microarchitecture (trabecular separation and thickness, porosity) of bone in the defect were quantified with time using microCT. The presence or activity of vascular endothelial cells (CD34), macrophages (F4/80), osteoblasts (alkaline phosphatase [ALP]), and osteoclasts (tartrate-resistant acid phosphatase [TRAP]) were evaluated using histochemical analyses. Only one of eight defects was bridged completely 6 weeks after surgery in LPS-injected mouse bones compared with seven of nine defects in the control mouse bones (odds ratio [OR], 0.04; 95% CI, 0.003-0.560; p = 0.007). The decrease in cortical bone in LPS-treated mice was reflected in reduced BV/TV (21% ± 4% vs 39% ± 10%; p inflammation reduced the amount and impaired the quality of bone regenerated in mouse femurs. The effects were associated with impaired revascularization

  17. Use of Preputial Skin as Cutaneous Graft after Nevus Excision

    Directory of Open Access Journals (Sweden)

    A. D'Alessio

    2010-01-01

    Full Text Available We report a four-year-old boy with a nevus covering all the plantar side of his second finger on the left foot. He was also affected by congenital phimosis. Surgical excision of the nevus was indicated, but the skin defect would have been too large to be directly closed. The foreskin was taken as a full-thickness skin graft to cover the cutaneous defect of the finger. The graft intake was favourable and provided a functional repair with good aesthetic characteristic.

  18. Repair of long bone defects with demineralized bone matrix and autogenous bone composite

    Directory of Open Access Journals (Sweden)

    Mehmet T Ozdemir

    2011-01-01

    Full Text Available Background: Repair of diaphyseal bone defects is a challenging problem for orthopedic surgeons. In large bone defects the quantity of harvested autogenous bone may not be sufficient to fill the gap and then the use of synthetic or allogenic grafts along with autogenous bone becomes mandatory to achieve compact filling. Finding the optimal graft mixture for treatment of large diaphyseal defects is an important goal in contemporary orthopedics and this was the main focus of this study. The aim of this study is to investigate the efficacy of demineralized bone matrix (DBM and autogenous cancellous bone (ACB graft composite in a rabbit bilateral ulna segmental defect model. Materials and Methods: Twenty-seven adult female rabbits were divided into five groups. A two-centimeter piece of long bone on the midshaft of the ulna was osteotomized and removed from the rabbits′ forearms. In group 1 (n=7 the defects were treated with ACB, in group 2 (n=7 with DBM, and in group 3 (n=7 with ACB and DBM in the ratio of 1:1. Groups 4 and 5, with three rabbits in each group, were the negative and positive controls, respectively. Twelve weeks after implantation the rabbits were sacrificed and union was evaluated with radiograph (Faxitron, dual-energy x-ray absorptiometry (DEXA, and histological methods (decalcified sectioning. Results: Union rates and the volume of new bone in the different groups were as follows: group 1 - 92.8% union and 78.6% new bone; group 2 - 72.2% union and 63.6% new bone; and group 3 - 100% union and 100% new bone. DEXA results (bone mineral density [BMD] were as follows: group 1 - 0.164 g/cm 2 , group 2 - 0.138 g/cm 2 , and group 3 - 0.194 g/cm 2 . Conclusions: DBM serves as a graft extender or enhancer for autogenous graft and decreases the need of autogenous bone graft in the treatment of bone defects. In this study, the DBM and ACB composite facilitated the healing process. The union rate was better with the combination than with the

  19. The physical properties of two biomaterials and their effects in repairing abdominal wall defects in rat

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    Guan-yu WANG

    2011-05-01

    Full Text Available Objective To compare the physical properties of porcine small intestinal submucosa(P-SIS and porcine pericardium(P-PC and their effects in repairing abdominal wall defects in rat,in order to look for a more suitable biomaterial for repairing abdominal wall defect.Methods P-SIS and P-PC were harvested from 5 BA-MA Mini-Pigs(around 50kg within 4h of sacrifice.P-SIS was prepared with Abraham’s method,and P-PC was prepared with Trypsin+Triton X-100 method.The strength against butting force,strength against expansion force,water vapor permeability,thickness and tensile strength were then respectively tested.48 male SD rats weighed from 290g to 310g were randomly divided into 2 groups(24 each.Abdominal wall defects(3cm×2cm were created by surgery and repaired with P-SIS or P-PC respectively.Animals were sacrificed at the 2nd,4th,6th and 8th week after operation.The tensile strength and expansion rate of implanted materials and the development of adhesions were measured and observed.Results The thickness of P-PC(0.17±0.01mm was about 3 times that of P-SIS(0.05±0.01mm;The strength against expansion force of P-PC(52.10±6.50 Psi was about 8 times that of P-SIS(6.70±0.45 Psi;The strength against butting force of P-PC(166.86±16.15N was about 6 times of P-SIS(25.94±2.92N;The tensile strength of P-PC(31.80±6.16MPa was about 3 times that of P-SIS(11.81±2.50MPa.The water vapor permeability of P-SIS [4772.82±279.64 g/(m2·d] was about 1.5 times that of P-PC [3108.28±233.69g/(m2·d].The tensile strength of both materials declined significantly after implantation,recovered slowly from the 4th week on,and returned to normal after 6 weeks.The area of P-SIS implant gradually shrank after implantation;the implanted area of P-PC was 5.05±0.27cm2 at the 2nd week,9.99±0.89cm2 at the 4th week,6.83±0.19cm2 at the 6th week,and 10.63±0.91cm2 at the 8th week.The implanted area of P-PC was larger than that of P-SIS 4 weeks after implantation(P < 0.05.The

  20. Near miss sudden cardiac death on a young patient with repaired atrioventricular septal defect.

    Science.gov (United States)

    Papadopoulou, Sofia A; Dimopoulos, Konstantinos; Gatzoulis, Michael A

    2008-11-28

    Patients with congenital heart disease often face the prospect of long-term haemodynamic or arrhythmic complications for which lifelong follow-up in specialist adult congenital heart disease (ACHD) centres is required. We describe the case of a 25-year-old man with repaired atrioventricular septal defect who was referred to our centre after a ventricular fibrillation arrest. Serial echocardiograms in previous years had shown progressive severe left ventricular outflow obstruction, but the patient had not been operated on as he was deemed asymptomatic and reluctant to consider surgery. Management and criteria for further intervention in ACHD patients often differ from those of patients with acquired heart disease and reliance on symptoms alone is not good practice and may prove catastrophic.

  1. A polymorphism in the base excision repair gene PARP2 is associated with differential prognosis by chemotherapy among postmenopausal breast cancer patients.

    Science.gov (United States)

    Seibold, Petra; Schmezer, Peter; Behrens, Sabine; Michailidou, Kyriaki; Bolla, Manjeet K; Wang, Qin; Flesch-Janys, Dieter; Nevanlinna, Heli; Fagerholm, Rainer; Aittomäki, Kristiina; Blomqvist, Carl; Margolin, Sara; Mannermaa, Arto; Kataja, Vesa; Kosma, Veli-Matti; Hartikainen, Jaana M; Lambrechts, Diether; Wildiers, Hans; Kristensen, Vessela; Alnæs, Grethe Grenaker; Nord, Silje; Borresen-Dale, Anne-Lise; Hooning, Maartje J; Hollestelle, Antoinette; Jager, Agnes; Seynaeve, Caroline; Li, Jingmei; Liu, Jianjun; Humphreys, Keith; Dunning, Alison M; Rhenius, Valerie; Shah, Mitul; Kabisch, Maria; Torres, Diana; Ulmer, Hans-Ulrich; Hamann, Ute; Schildkraut, Joellen M; Purrington, Kristen S; Couch, Fergus J; Hall, Per; Pharoah, Paul; Easton, Doug F; Schmidt, Marjanka K; Chang-Claude, Jenny; Popanda, Odilia

    2015-12-16

    Personalized therapy considering clinical and genetic patient characteristics will further improve breast cancer survival. Two widely used treatments, chemotherapy and radiotherapy, can induce oxidative DNA damage and, if not repaired, cell death. Since base excision repair (BER) activity is specific for oxidative DNA damage, we hypothesized that germline genetic variation in this pathway will affect breast cancer-specific survival depending on treatment. We assessed in 1,408 postmenopausal breast cancer patients from the German MARIE study whether cancer specific survival after adjuvant chemotherapy, anthracycline chemotherapy, and radiotherapy is modulated by 127 Single Nucleotide Polymorphisms (SNPs) in 21 BER genes. For SNPs with interaction terms showing p<0.1 (likelihood ratio test) using multivariable Cox proportional hazard analyses, replication in 6,392 patients from nine studies of the Breast Cancer Association Consortium (BCAC) was performed. rs878156 in PARP2 showed a differential effect by chemotherapy (p=0.093) and was replicated in BCAC studies (p=0.009; combined analysis p=0.002). Compared to non-carriers, carriers of the variant G allele (minor allele frequency=0.07) showed better survival after chemotherapy (combined allelic hazard ratio (HR)=0.75, 95% 0.53-1.07) and poorer survival when not treated with chemotherapy (HR=1.42, 95% 1.08-1.85). A similar effect modification by rs878156 was observed for anthracycline-based chemotherapy in both MARIE and BCAC, with improved survival in carriers (combined allelic HR=0.73, 95% CI 0.40-1.32). None of the SNPs showed significant differential effects by radiotherapy. Our data suggest for the first time that a SNP in PARP2, rs878156, may together with other genetic variants modulate cancer specific survival in breast cancer patients depending on chemotherapy. These germline SNPs could contribute towards the design of predictive tests for breast cancer patients.

  2. Polymorphisms in base excision repair genes as colorectal cancer risk factors and modifiers of the effect of diets high in red meat

    Science.gov (United States)

    Brevik, Asgeir; Joshi, Amit D.; Corral, Román; Onland-Moret, N. Charlotte; Siegmund, Kimberly D.; Le Marchand, Loïc; Baron, John A.; Martinez, Maria Elena; Haile, Robert W.; Ahnen, Dennis J.; Sandler, Robert S.; Lance, Peter; Stern, Mariana C.

    2010-01-01

    Background A diet high in red meat is an established colorectal cancer (CRC) risk factor. Carcinogens generated during meat cooking have been implicated as causal agents, and can induce oxidative DNA damage, which elicits repair by the base excision repair (BER) pathway. Methods Using a family-based study we investigated the role of polymorphisms in four BER genes (APEX1 Gln51His, Asp148Glu; OGG1 Ser236Cys; PARP Val742Ala; XRCC1 Arg194Trp, Arg280His, Arg399Gln) as potential CRC risk factors and modifiers of the association between high-red meat or poultry diets and CRC risk. We tested for gene-environment interactions using case-only analyses (N = 577) and compared statistically significant results to those obtained using case-unaffected sibling comparisons (N = 307 sibships). Results Carriers of the APEX1 codon 51 Gln/His genotype had a reduced CRC risk compared to carriers of the Gln/Gln genotype (OR 0.15, 95% CI 0.03-0.69, p = 0.015). The association between higher red meat intake (>3 servings/week) and CRC was modified by the PARP Val762Ala SNP (case-only interaction p = 0.026). This SNP also modified the association between higher intake of high-temperature cooked red meat (case-only interaction p = 0.0009). Conclusions We report evidence that the BER pathway PARP gene modifies the association of diets high in red meat cooked at high temperatures with risk of CRC. Impact Our findings suggest a contribution to colorectal carcinogenesis of free radical damage as one of the possible harmful effects of a high-red meat diet. PMID:21037106

  3. 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. The second one ...

  4. Off-Pump Repair of a Post Myocardial Infarction Ventricular Septal Defect

    Directory of Open Access Journals (Sweden)

    Feridoun Sabzi

    2014-01-01

    Full Text Available Refractory cardiogenic shock meant that traditional patch repairs requiring cardiopulmonary bypass would be poorly tolerated and external sandwich closure of post myocardial ventricular septal defect (VSD appears to be simple and effective after initial myocardial infarction (MI. The three cases presented with a VSD after of acute MI with or without thrombolysed with streptokinase during patient admission. The general condition of the three patients was poor with pulmonary edema, low cardiac output and renal failure. The heart was approached through a median sternotomy. Off-pump coronary artery bypass grafting of the coronary artery lesion was done first using octopus and beating heart surgery method and latero - lateral septal plication was performed using sandwich technique. Low cardiac output managed with intra-aortic balloon pump in these patients accompanied with inotropic drugs. Post-operative transesophageal echocardiography revealed that VSD was closed completely in one patient and in two patients small residual VSD remained. More experience is required to ascertain whether this technique will become an accepted alternative to patch repairs.

  5. Mutations in UVSSA cause UV-sensitive syndrome and impair RNA polymerase IIo processing in transcription-coupled nucleotide-excision repair.

    Science.gov (United States)

    Nakazawa, Yuka; Sasaki, Kensaku; Mitsutake, Norisato; Matsuse, Michiko; Shimada, Mayuko; Nardo, Tiziana; Takahashi, Yoshito; Ohyama, Kaname; Ito, Kosei; Mishima, Hiroyuki; Nomura, Masayo; Kinoshita, Akira; Ono, Shinji; Takenaka, Katsuya; Masuyama, Ritsuko; Kudo, Takashi; Slor, Hanoch; Utani, Atsushi; Tateishi, Satoshi; Yamashita, Shunichi; Stefanini, Miria; Lehmann, Alan R; Yoshiura, Koh-ichiro; Ogi, Tomoo

    2012-05-01

    UV-sensitive syndrome (UV(S)S) is a genodermatosis characterized by cutaneous photosensitivity without skin carcinoma. Despite mild clinical features, cells from individuals with UV(S)S, like Cockayne syndrome cells, are very UV sensitive and are deficient in transcription-coupled nucleotide-excision repair (TC-NER), which removes DNA damage in actively transcribed genes. Three of the seven known UV(S)S cases carry mutations in the Cockayne syndrome genes ERCC8 or ERCC6 (also known as CSA and CSB, respectively). The remaining four individuals with UVSS , one of whom is described for the first time here, formed a separate UV(S)S-A complementation group; however, the responsible gene was unknown. Using exome sequencing, we determine that mutations in the UVSSA gene (formerly known as KIAA1530) cause UV(S)S-A. The UVSSA protein interacts with TC-NER machinery and stabilizes the ERCC6 complex; it also facilitates ubiquitination of RNA polymerase IIo stalled at DNA damage sites. Our findings provide mechanistic insights into the processing of stalled RNA polymerase and explain the different clinical features across these TC-NER–deficient disorders.

  6. [The expression of thymidylate synthase (TS) and excision repair complementing-1 (ERCC-1) protein in patients with unresectable colorectal cancer treated with mFOLFOX6 therapy].

    Science.gov (United States)

    Ishibashi, Keiichiro; Okada, Norimichi; Ishiguro, Toru; Kuwabara, Kouki; Ohsawa, Tomonori; Yokoyama, Masaru; Kumamoto, Kensuke; Haga, Norihiro; Mori, Takashi; Yamada, Hirofumi; Miura, Ichiro; Tamaru, Junichi; Itoyama, Shinji; Ishida, Hideyuki

    2010-11-01

    Thymidylate synthase (TS) and excision repair complementing-1 (ERCC-1) were known to be important biomarkers to predict a tumor response to 5-fluorouracil (5-FU) and oxaliplatin, but the relationship between these expressions and tumor response were still unclear. The aim of this study was to determine whether the expression of TS and ERCC-1 protein predict a tumor response in patients with unresectable colorectal cancer treated with mFOLFOX6 therapy as first-line treatment. Fifty patients with unresectable colorectal cancer treated with mFOLFOX6 therapy were enrolled in this study. The expression of TS and ERCC-1 protein in primary cancer cells were examined using immunohistochemistry. There were no significant differences between response rate and the expression of TS or ERCC-1 protein (TS: p>0.99, ERCC-1: p= 0.50). There were no significant differences between progression-free survival time and the expression of TS or ERCC-1 protein (TS: p=0.60, ERCC-1: p=0.60). In this study, the expression TS and ERCC-1 protein may not be useful for the prediction of tumor response in patients with unresectable colorectal cancer treated with mFOLFOX6 therapy.

  7. Repair of osteochondral defects with biodegradable hydrogel composites encapsulating marrow mesenchymal stem cells in a rabbit model.

    NARCIS (Netherlands)

    Guo, X.; Park, H.; Young, S.; Kretlow, J.D.; Beucken, J.J.J.P. van den; Baggett, L.S.; Tabata, Y.; Kasper, F.K.; Mikos, A.G.; Jansen, J.A.

    2010-01-01

    This work investigated the delivery of marrow mesenchymal stem cells (MSCs), with or without the growth factor transforming growth factor-beta1 (TGF-beta1), from biodegradable hydrogel composites on the repair of osteochondral defects in a rabbit model. Three formulations of oligo(poly(ethylene

  8. Simultaneous repair of two large cranial defects using rapid prototyping and custom computer-designed titanium plates: a case report.

    Science.gov (United States)

    Morrison, D A; Guy, D T; Day, R E; Lee, G Y F

    2011-11-01

    Custom titanium cranioplasty plates, manufactured by a variety of techniques, have been used to repair a range of cranial defects. The authors present a case where two relatively large, adjacent cranial defects were repaired by custom computer-designed titanium plates. The two plates were designed and fabricated simultaneously using a unique methodology. A 28-year-old woman underwent a corpus callosotomy for medically intractable epilepsy. The surgery was complicated by unexpected haemorrhage which necessitated a second craniotomy. Subsequent deep infection required the removal of bilateral bone flaps, presenting a challenge in the reconstruction of extensive, bilateral but asymmetrical cranial defects. The patient underwent a head computed tomography scan, from which a rapid-prototype model of the skull was produced. The surfaces for the missing cranial segments were generated virtually using a combination of software products and two titanium plates that followed these virtual contours were manufactured to cover the defects. The cranioplasty procedure to implant both titanium cranial plates was performed efficiently with no intra-operative complications. Intra-operatively, an excellent fit was achieved. The careful planning of the plates enhanced the relative ease with which the cranial defects were repaired with an excellent cosmetic outcome.

  9. Determination of Isthmocele Using a Foley Catheter During Laparoscopic Repair of Cesarean Scar Defect.

    Science.gov (United States)

    Akdemir, Ali; Sahin, Cagdas; Ari, Sabahattin Anil; Ergenoglu, Mete; Ulukus, Murat; Karadadas, Nedim

    2018-01-01

    To demonstrate a new technique of isthmocele repair via laparoscopic surgery. Case report (Canadian Task Force classification III). The local Ethics Committee waived the requirement for approval. Isthmocele localized at a low uterine segment is a defect of a previous caesarean scar due to poor myometrial healing after surgery [1]. This pouch accumulates menstrual bleeding, which can cause various disturbances and irregularities, including abnormal uterine bleeding, infertility, pelvic pain, and scar pregnancy [2-6]. Given the absence of a clearly defined surgical method in the literature, choosing the proper approach to treating isthmocele can be arduous. Laparoscopy provides a minimally invasive procedure in women with previous caesarean scar defects. A 28-year-old woman, gravida 2 para 2, presented with a complaint of prolonged postmenstrual bleeding for 5 years. She had undergone 2 cesarean deliveries. Transvaginal ultrasonography revealed a hypoechogenic area with menstrual blood in the anterior lower uterine segment. Magnetic resonance imaging showed an isthmocele localized at the anterior left lateral side of the uterus, with an estimated volume of approximately 12 cm3. After patient preparation, laparoscopy was performed. To repair the defect, the uterovesical peritoneal fold was incised and the bladder was mobilized from the lower uterine segment. During this surgery, differentiating the isthmocele from the abdomen can be challenging. Here we used a Foley catheter to identify the isthmocele. To do this, after mobilizing the bladder from the lower uterine segment, we inserted a Foley catheter into the uterine cavity through the cervical canal. We then filled the balloon of the catheter at the lower uterine segment under laparoscopic view, which allowed clear identification of the isthmocele pouch. The uterine defect was then incised. The isthmocele cavity was accessed, the margins of the pouch were debrided, and the edges were surgically reapproximated with

  10. Two modes of microsatellite instability in human cancer: differential connection of defective DNA mismatch repair to dinucleotide repeat instability

    Science.gov (United States)

    Oda, Shinya; Maehara, Yoshihiko; Ikeda, Yoichi; Oki, Eiji; Egashira, Akinori; Okamura, Yoshikazu; Takahashi, Ikuo; Kakeji, Yoshihiro; Sumiyoshi, Yasushi; Miyashita, Kaname; Yamada, Yu; Zhao, Yan; Hattori, Hiroyoshi; Taguchi, Ken-ichi; Ikeuchi, Tatsuro; Tsuzuki, Teruhisa; Sekiguchi, Mutsuo; Karran, Peter; Yoshida, Mitsuaki A.

    2005-01-01

    Microsatellite instability (MSI) is associated with defective DNA mismatch repair in various human malignancies. Using a unique fluorescent technique, we have observed two distinct modes of dinucleotide microsatellite alterations in human colorectal cancer. Type A alterations are defined as length changes of ≤6 bp. Type B changes are more drastic and involve modifications of ≥8 bp. We show here that defective mismatch repair is necessary and sufficient for Type A changes. These changes were observed in cell lines and in tumours from mismatch repair gene-knockout mice. No Type B instability was seen in these cells or tumours. In a panel of human colorectal tumours, both Type A MSI and Type B instability were observed. Both types of MSI were associated with hMSH2 or hMLH1 mismatch repair gene alterations. Intriguingly, p53 mutations, which are generally regarded as uncommon in human tumours of the MSI+ phenotype, were frequently associated with Type A instability, whereas none was found in tumours with Type B instability, reflecting the prevailing viewpoint. Inspection of published data reveals that the microsatellite instability that has been observed in various malignancies, including those associated with Hereditary Non-Polyposis Colorectal Cancer (HNPCC), is predominantly Type B. Our findings indicate that Type B instability is not a simple reflection of a repair defect. We suggest that there are at least two qualitatively distinct modes of dinucleotide MSI in human colorectal cancer, and that different molecular mechanisms may underlie these modes of MSI. The relationship between MSI and defective mismatch repair may be more complex than hitherto suspected. PMID:15778432

  11. Enhanced repair of segmental bone defects in rabbit radius by porous tantalum scaffolds modified with the RGD peptide.

    Science.gov (United States)

    Wang, Hui; Li, Qijia; Wang, Qian; Zhang, Hui; Shi, Wei; Gan, Hongquan; Song, Huiping; Wang, Zhiqiang

    2017-03-01

    Fast and stable repair of segmental bone defects remains a challenge for clinical orthopedic surgery. In recent years, porous tantalum has been widely applied in clinical orthopedics for low modulus of elasticity, with three-dimensional microstructures similar to cancellous bone and excellent biocompatibility. To further improve bone the repairing ability of porous tantalum, the cyclo(-RGDfK-) peptide was coated on the surface of porous tantalum scaffolds. A model of 15 mm segmental defect was made at the midshaft of right radius in New Zealand White rabbits. In the experimental group, defects were implanted (press-fit) using porous tantalum scaffolds modified with cyclo(-RGDfK-) peptide. Control animals were implanted with non-modified porous tantalum scaffolds or xenogeneic cancellous bone scaffolds, respectively. No implant was provided for the blank group. Bone repair was assessed by X-ray and histological observations at 4, 8, and 16 weeks post-operation, with biomechanical tests and micro-computed tomography performed at 16 weeks post-surgery. The results showed that bone formation was increased at the interface and inside the inner pores of modified porous tantalum scaffolds than those of non-modified porous tantalum scaffolds; biomechanical properties in the modified porous tantalum group were superior to those of the non-modified porous tantalum and xenogeneic cancellous bone groups, while new bone volume fractions using micro-computed tomography analysis were similar between the modified porous tantalum and xenogeneic cancellous bone groups. Our findings suggested that modified porous tantalum scaffolds had enhanced repairing ability in segmental bone defect in rabbit radius, and may serve as a potential material for repairing large bone defects.

  12. Percutaneous Direct Repair of a Pars Defect Using Intraoperative Computed Tomography Scan: A Modification of the Buck Technique.

    Science.gov (United States)

    Nourbakhsh, Ali; Preuss, Fletcher; Hadeed, Michael; Shimer, Adam

    2017-06-01

    Case report. To describe a young adult with a pars defect undergoing percutaneous direct fixation using intraoperative computed tomography (CT) scan. Direct pars repair has been utilized since the 1960s. There are no reports in the literature describing a percutaneous technique. Using a percutaneous technique under the guide of intraoperative CT scan, a cannulated partially threaded screw was inserted across the pars defect. Surgery was completed without complication and the patient returned to preoperative activity level 3 months post-op. Postoperative CT scan showed a well-healed L4 pars defect. Percutaneous direct pars repair using intraoperative CT scan offers the advantage of minimal soft tissue dissection, thereby reducing blood loss, infection risk, and recovery time. 5.

  13. Anti-inflammatory and osteogenesis of complex particles composed of ceric oxide and bioglass on repair of rabbit femoral defects

    Directory of Open Access Journals (Sweden)

    Hai HUANG

    2011-02-01

    Full Text Available Objective To observe the anti-inflammatory and osteogenesis of the complex particles composed of ceric oxide and bioglass implanted into rabbit femoral defects.Methods The bilateral penetrating femoral condylar defects of 6mm in diameter were made in 6 adult New Zealand White rabbits,bioglass particles and complex particles composed of ceric oxide and bioglass were randomly implanted into the left or right condylar defect.Animals were sacrificed at 2 and 4 weeks after operation(3 each,specimens from defect sites were harvested for histological examination to observe the inflammatory reaction and calculate the ratio of new bone and grafts on the defect area.Results No inflammatory reaction was found in the defect area filled with bioglass particles or complex particles composed of ceric oxide and bioglass.New bone was observed in the defects 2 weeks after operation,and no significant difference on the bone formation rate existed between the two materials(P > 0.05.The osteogenesis of both materials was more obvious in the 4th week than in the 2nd week(P 0.05.No obvious degradation of the grafts implanted into the defect area occurred in the 4th week compared with that in the 2nd week(P > 0.05.Conclusion The complex particles composed of ceric oxide and bioglass has anti-inflammatory activity and similar osteogenesis to normal bioglass particles,and may be used in the repair of bone defects.

  14. No-touch aorta robot-assisted atrial septal defect repair via two ports.

    Science.gov (United States)

    Ishikawa, Norihiko; Watanabe, Go; Tarui, Tatsuya

    2018-01-02

    Atrial septal defect (ASD) repairs have been successfully performed on arrested hearts with robotic assistance. The present study assessed the feasibility, safety, and efficacy of totally endoscopic cardiac surgery using a no-touch aorta technique for ASD via only 2 ports, and we named this procedure two-port robotic cardiac surgery (TROCS). Between May 2014 and June 2016, 8 consecutive patients underwent TROCS for ASD using the da Vinci surgical system (Intuitive Surgical Inc.) at our institute. All of the procedures were performed via only 2 port incisions in the right chest. One was the camera port, and the other was the port for the robotic instruments. Both robotic instruments were inserted through this port and crossed while being prevented from colliding with each other. The surgeon console was set to the reverse of default settings so that both masters would control the inverse instrument. TROCS for ASD was carried out under ventricular fibrillation induced by combinations of an electrical fibrillator, injection of potassium, and hypothermia without aortic cross-clamping. All cases were successfully repaired. The mean operation, cardiopulmonary bypass and ventricular fibrillation times were 129.6 ± 29.0 min, 66.9 ± 24.5 min and 9.6 ± 5.9 min, respectively, and the estimated blood loss volume was 28.1 ± 58.6 ml. No patients required blood transfusion during their hospital stay, and their cosmetic results were excellent. TROCS for ASD using no-touch aorta technique was achieved safely with good clinical results and excellent cosmetic results.

  15. Photocrosslinked layered gelatin-chitosan hydrogel with graded compositions for osteochondral defect repair.

    Science.gov (United States)

    Han, Fengxuan; Yang, Xiaoling; Zhao, Jin; Zhao, Yunhui; Yuan, Xiaoyan

    2015-04-01

    A layered gelatin-chitosan hydrogel with graded composition was prepared via photocrosslinking to simulate the polysaccharide/collagen composition of the natural tissue and mimic the multi-layered gradient structure of the cartilage-bone interface tissue. Firstly, gelatin and carboxymethyl chitosan were reacted with glycidyl methacrylate (GMA) to obtain methacrylated gelatin (Gtn-GMA) and carboxymethyl chitosan (CS-GMA). Then, the mixed solutions of Gtn-GMA in different methacrylation degrees with CS-GMA were prepared to form the superficial, transitional and deep layers of the hydrogel, respectively under the irradiation of ultraviolet light, while polyhedral oligomeric silsesquioxane was introduced in the deep layer to improve the mechanical properties. Results suggested that the pore sizes of the superficial, transitional and deep layers of the layered hydrogel were 115 ± 30, 94 ± 34, 51 ± 12 μm, respectively and their porosities were all higher than 80 %. The compressive strengths of them were 165 ± 54, 565 ± 50 and 993 ± 108 kPa, respectively and the strain of the gradient hydrogel decreased along the thickness direction, similar to the natural tissue. The in vitro cytotoxicity results showed that the hydrogel had good cytocompatibility and the in vivo repair results of osteochondral defect demonstrated remarkable recovery by using the gradient gelatin-chitosan hydrogel, especially when the hydrogel loading transforming growth factor-β1. Therefore, it was suggested that the prepared layered gelatin-chitosan hydrogel in this study could be potentially used to promote cartilage-bone interface tissue repair.

  16. Molecular and cellular analysis of the DNA repair defect in a patient in Xeroderma pigmentosum complementation group D who has the clinical features of Xeroderma pigmentosum and Cockayne syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Broughton, B.C.; Thompson, A.F.; Harcourt, S.A.; Cole, J.; Arlett, C.F.; Lehmann, A.R. [Univ. of Sussex, Brighton (United Kingdom); Vermeulen, W.; Hoeijmakers, J.H.J. [Erasmus Univ., Rotterdam (United Kingdom); Botta, E.; Stefanini, M. [Istituto di Genetica, Pavia (Italy)] [and others

    1995-01-01

    Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are quite distinct genetic disorders that are associated with defects in excision repair of UV-induced DNA damage. A few patients have been described previously with the clinical features of both disorders. In this paper we describe an individual in this category who has unusual cellular responses to UV light. We show that his cultured fibroblasts and lymphocytes are extremely sensitive to irradiation with UV-C, despite a level of nucleotide excision repair that is 30%-40% that of normal cells. The deficiency is assigned to the XP-D complementation group, and we have identified two causative mutations in the XPD gene: a gly{yields}arg change at amino acid 675 in the allele inherited from the patient`s mother and a -1 frameshift at amino acid 669 in the allele inherited from his father. These mutations are in the C-terminal 20% of the 760-amino-acid XPD protein, in a region where we have recently identified several mutations in patients with trichothiodystrophy. 44 refs., 5 figs., 2 tabs.

  17. Molecular and cellular analysis of the DNA repair defect in a patient in xeroderma pigmentosum complementation group D who has the clinical features of xeroderma pigmentosum and Cockayne syndrome.

    Science.gov (United States)

    Broughton, B C; Thompson, A F; Harcourt, S A; Vermeulen, W; Hoeijmakers, J H; Botta, E; Stefanini, M; King, M D; Weber, C A; Cole, J

    1995-01-01

    Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are quite distinct genetic disorders that are associated with defects in excision repair of UV-induced DNA damage. A few patients have been described previously with the clinical features of both disorders. In this paper we describe an individual in this category who has unusual cellular responses to UV light. We show that his cultured fibroblasts and lymphocytes are extremely sensitive to irradiation with UV-C, despite a level of nucleotide excision repair that is 30%-40% that of normal cells. The deficiency is assigned to the XP-D complementation group, and we have identified two causative mutations in the XPD gene: a gly-->arg change at amino acid 675 in the allele inherited from the patient's mother and a -1 frameshift at amino acid 669 in the allele inherited from his father. These mutations are in the C-terminal 20% of the 760-amino-acid XPD protein, in a region where we have recently identified several mutations in patients with trichothiodystrophy.

  18. Lys98 substitution in human AP endonuclease 1 affects the kinetic mechanism of enzyme action in base excision and nucleotide incision repair pathways.

    Directory of Open Access Journals (Sweden)

    Nadezhda A Timofeyeva

    Full Text Available Human apurinic/apyrimidinic endonuclease 1 (APE1 is a key enzyme in the base excision repair (BER and nucleotide incision repair (NIR pathways. We recently analyzed the conformational dynamics and kinetic mechanism of wild-type (wt protein, in a stopped-flow fluorescence study. In this study, we investigated the mutant enzyme APE1K98A using the same approach. Lys98 was known to hydrogen bond to the carboxyl group of Asp70, a residue implicated in binding the divalent metal ion. Our data suggested that the conformational selection and induced fit occur during the enzyme action. We expanded upon the evidence that APE1 can pre-exist in two conformations. The isomerization of an enzyme-product complex in the BER process and the additional isomerization stage of enzyme-substrate complex in the NIR process were established for APE1K98A. These stages had not been registered for the wtAPE1. We found that the K98A substitution resulted in a 12-fold reduction of catalytic constant of 5'-phosphodiester bond hydrolysis in (3-hydroxytetrahydrofuran-2-ylmethyl phosphate (F, tetrahydrofuran containing substrate, and in 200-fold reduction in 5,6-dihydrouridine (DHU containing substrate. Thus, the K98A substitution influenced NIR more than BER. We demonstrated that the K98A mutation influenced the formation of primary unspecific enzyme-substrate complex in a complicated manner, depending on the Mg(2+ concentration and pH. This mutation obstructed the induced fit of enzyme in the complex with undamaged DNA and F-containing DNA and appreciably decreased the stability of primary complex upon interaction of enzyme with DNA, containing the natural apurinic/apyrimidinic (AP site. Furthermore, it significantly delayed the activation of the less active form of enzyme during NIR and slowed down the conformational conversion of the complex of enzyme with the cleavage product of DHU-substrate. Our data revealed that APE1 uses the same active site to catalyze the cleavage

  19. Variation within 3'-UTRs of base excision repair genes and response to therapy in colorectal cancer patients: A potential modulation of microRNAs binding.

    Science.gov (United States)

    Pardini, Barbara; Rosa, Fabio; Barone, Elisa; Di Gaetano, Cornelia; Slyskova, Jana; Novotny, Jan; Levy, Miroslav; Garritano, Sonia; Vodickova, Ludmila; Buchler, Tomas; Gemignani, Federica; Landi, Stefano; Vodicka, Pavel; Naccarati, Alessio

    2013-11-01

    Colorectal cancer is routinely treated with a 5-fluorouracil (5-FU)-based chemotherapy. 5-FU incorporates into DNA, and the base excision repair (BER) pathway specifically recognizes such damage. We investigated the association of single-nucleotide polymorphisms (SNP) in the 3'-untranslated regions (UTR) of BER genes, and potentially affecting the microRNA (miRNA) binding, on the risk of colorectal cancer, its progression, and prognosis. SNPs in miRNA-binding sites may modulate the posttranscriptional regulation of gene expression operated by miRNAs and explain interindividual variability in BER capacity and response to 5-FU. We tested 12 SNPs in the 3'-UTRs of five BER genes for colorectal cancer susceptibility in a case-control study (1,098 cases and 1,459 healthy controls). Subsequently, we analyzed the role of these SNPs on clinical outcomes of patients (866 in the Training set and 232 in the Replication set). SNPs in the SMUG1 and NEIL2 genes were associated with overall survival. In particular, SMUG1 rs2233921 TT carriers showed increased survival compared with those with GT/GG genotypes [HR, 0.54; 95% confidence interval (CI), 0.36-0.81; P = 0.003] in the Training set and after pooling results from the Replication set. The association was more significant following stratification for 5-FU-based chemotherapy (P = 5.6 × 10(-5)). A reduced expression of the reporter gene for the T allele of rs2233921 was observed when compared with the common G allele by in vitro assay. None of the genotyped BER polymorphisms were associated with colorectal cancer risk. We provide the first evidence that variations in miRNA-binding sites in BER genes 3'-UTR may modulate colorectal cancer prognosis and therapy response.

  20. Base excision repair of chemotherapeutically-induced alkylated DNA damage predominantly causes contractions of expanded GAA repeats associated with Friedreich's ataxia.

    Directory of Open Access Journals (Sweden)

    Yanhao Lai

    Full Text Available Expansion of GAA·TTC repeats within the first intron of the frataxin gene is the cause of Friedreich's ataxia (FRDA, an autosomal recessive neurodegenerative disorder. However, no effective treatment for the disease has been developed as yet. In this study, we explored a possibility of shortening expanded GAA repeats associated with FRDA through chemotherapeutically-induced DNA base lesions and subsequent base excision repair (BER. We provide the first evidence that alkylated DNA damage induced by temozolomide, a chemotherapeutic DNA damaging agent can induce massive GAA repeat contractions/deletions, but only limited expansions in FRDA patient lymphoblasts. We showed that temozolomide-induced GAA repeat instability was mediated by BER. Further characterization of BER of an abasic site in the context of (GAA20 repeats indicates that the lesion mainly resulted in a large deletion of 8 repeats along with small expansions. This was because temozolomide-induced single-stranded breaks initially led to DNA slippage and the formation of a small GAA repeat loop in the upstream region of the damaged strand and a small TTC loop on the template strand. This allowed limited pol β DNA synthesis and the formation of a short 5'-GAA repeat flap that was cleaved by FEN1, thereby leading to small repeat expansions. At a later stage of BER, the small template loop expanded into a large template loop that resulted in the formation of a long 5'-GAA repeat flap. Pol β then performed limited DNA synthesis to bypass the loop, and FEN1 removed the long repeat flap ultimately causing a large repeat deletion. Our study indicates that chemotherapeutically-induced alkylated DNA damage can induce large contractions/deletions of expanded GAA repeats through BER in FRDA patient cells. This further suggests the potential of developing chemotherapeutic alkylating agents to shorten expanded GAA repeats for treatment of FRDA.

  1. Graphene oxide nanosheets induce DNA damage and activate the base excision repair (BER) signaling pathway both in vitro and in vivo.

    Science.gov (United States)

    Lu, Chun-Jiao; Jiang, Xue-Feng; Junaid, Muhammad; Ma, Yan-Bo; Jia, Pan-Pan; Wang, Hua-Bin; Pei, De-Sheng

    2017-10-01

    Graphene oxide (GO) has widespread concerns in the fields of biological sciences and medical applications. Currently, studies have reported that excessive GO exposure can cause cellular DNA damage through reactive oxygen species (ROS) generation. However, DNA damage mediated response of the base excision repair (BER) pathway due to GO exposure is not elucidated yet. Therefore, we exposed HEK293T cells and zebrafish embryos to different concentrations of GO for 24 h, and transcriptional profiles of BER pathway genes, DNA damage, and cell viability were analyzed both in vitro and in vivo. Moreover, the deformation of HEK293T cells before and after GO exposure was also investigated using atomic force microscopy (AFM) to identify the physical changes occurred in the cells' structure. CCK-8 and Comet assay revealed the significant decrease in cell viability and increase in DNA damage in HEK293T cells at higher GO doses (25 and 50 μg/mL). Among the investigated genetic markers in HEK293T cells, BER pathway genes (APEX1, OGG1, CREB1, UNG) were significantly up-regulated upon exposure to higher GO dose (50 μg/mL), however, low exposure concentration (5, 25 μg/mL) failed to induce significant genetic induction except for CREB1 at 25 μg/mL. Additionally, the viscosity of HEK293T cells decreased upon GO exposure. In zebrafish, the results of up-regulated gene expressions (apex1, ogg1, polb, creb1) were consistent with those in the HEK293T cells. Taken all together, the exposure to elevated GO concentration could cause DNA damage to HEK293T cells and zebrafish embryos; BER pathway could be proposed as the possible inner response mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Excision repair cross-complementation group 1 protein expression predicts survival in patients with high-grade, non-metastatic osteosarcoma treated with neoadjuvant chemotherapy.

    Science.gov (United States)

    Hattinger, Claudia Maria; Michelacci, Francesca; Sella, Federica; Magagnoli, Giovanna; Benini, Stefania; Gambarotti, Marco; Palmerini, Emanuela; Picci, Piero; Serra, Massimo; Ferrari, Stefano

    2015-09-01

    To evaluate the clinical impact of excision repair cross-complementation group 1 (ERCC1) expression in high-grade osteosarcoma (OS). Immunohistochemistry was performed on biopsies from 99 OS patients enrolled in the ISG/OS-Oss training set or ISG/SSG1 validation set neoadjuvant chemotherapy protocols, based on the use of cisplatin, adriamycin, methotrexate, and ifosfamide. In the training set, ERCC1 positivity was found in eight of 31 (26%) patients, and was significantly associated with worse event-free survival (EFS) (P = 0.042) and overall survival (OVS) (P = 0.001). In the validation set, ERCC1 positivity was found in 22 of 68 (32%) patients, and its significant associations with poorer EFS (P = 0.028) and OVS (P = 0.022) were confirmed. Multivariate analyses performed on the whole patient series indicated that ERCC1 positivity was the only marker that was significantly associated with a higher risk of worse prognosis, in terms of both EFS and OVS (P = 0.013). Co-evaluation of ERCC1 and ABCB1 expression showed that patients who were positive for both markers had a significantly worse prognosis. The ERCC1 level at diagnosis is predictive for the outcome of patients with non-metastatic, high-grade OS treated with neoadjuvant chemotherapy, and co-evaluation with ABCB1 can identify high-risk groups of OS patients who are refractory to standard regimens. © 2015 John Wiley & Sons Ltd.

  3. DNA glycosylases involved in base excision repair may be associated with cancer risk in BRCA1 and BRCA2 mutation carriers.

    Directory of Open Access Journals (Sweden)

    Ana Osorio

    2014-04-01

    Full Text Available Single Nucleotide Polymorphisms (SNPs in genes involved in the DNA Base Excision Repair (BER pathway could be associated with cancer risk in carriers of mutations in the high-penetrance susceptibility genes BRCA1 and BRCA2, given the relation of synthetic lethality that exists between one of the components of the BER pathway, PARP1 (poly ADP ribose polymerase, and both BRCA1 and BRCA2. In the present study, we have performed a comprehensive analysis of 18 genes involved in BER using a tagging SNP approach in a large series of BRCA1 and BRCA2 mutation carriers. 144 SNPs were analyzed in a two stage study involving 23,463 carriers from the CIMBA consortium (the Consortium of Investigators of Modifiers of BRCA1 and BRCA2. Eleven SNPs showed evidence of association with breast and/or ovarian cancer at p<0.05 in the combined analysis. Four of the five genes for which strongest evidence of association was observed were DNA glycosylases. The strongest evidence was for rs1466785 in the NEIL2 (endonuclease VIII-like 2 gene (HR: 1.09, 95% CI (1.03-1.16, p = 2.7 × 10(-3 for association with breast cancer risk in BRCA2 mutation carriers, and rs2304277 in the OGG1 (8-guanine DNA glycosylase gene, with ovarian cancer risk in BRCA1 mutation carriers (HR: 1.12 95%CI: 1.03-1.21, p = 4.8 × 10(-3. DNA glycosylases involved in the first steps of the BER pathway may be associated with cancer risk in BRCA1/2 mutation carriers and should be more comprehensively studied.

  4. DNA Glycosylases Involved in Base Excision Repair May Be Associated with Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

    Science.gov (United States)

    Osorio, Ana; Milne, Roger L.; Kuchenbaecker, Karoline; Vaclová, Tereza; Pita, Guillermo; Alonso, Rosario; Peterlongo, Paolo; Blanco, Ignacio; de la Hoya, Miguel; Duran, Mercedes; Díez, Orland; Ramón y Cajal, Teresa; Konstantopoulou, Irene; Martínez-Bouzas, Cristina; Andrés Conejero, Raquel; Soucy, Penny; McGuffog, Lesley; Barrowdale, Daniel; Lee, Andrew; SWE-BRCA; Arver, Brita; Rantala, Johanna; Loman, Niklas; Ehrencrona, Hans; Olopade, Olufunmilayo I.; Beattie, Mary S.; Domchek, Susan M.; Nathanson, Katherine; Rebbeck, Timothy R.; Arun, Banu K.; Karlan, Beth Y.; Walsh, Christine; Lester, Jenny; John, Esther M.; Whittemore, Alice S.; Daly, Mary B.; Southey, Melissa; Hopper, John; Terry, Mary B.; Buys, Saundra S.; Janavicius, Ramunas; Dorfling, Cecilia M.; van Rensburg, Elizabeth J.; Steele, Linda; Neuhausen, Susan L.; Ding, Yuan Chun; Hansen, Thomas v. O.; Jønson, Lars; Ejlertsen, Bent; Gerdes, Anne-Marie; Infante, Mar; Herráez, Belén; Moreno, Leticia Thais; Weitzel, Jeffrey N.; Herzog, Josef; Weeman, Kisa; Manoukian, Siranoush; Peissel, Bernard; Zaffaroni, Daniela; Scuvera, Giulietta; Bonanni, Bernardo; Mariette, Frederique; Volorio, Sara; Viel, Alessandra; Varesco, Liliana; Papi, Laura; Ottini, Laura; Tibiletti, Maria Grazia; Radice, Paolo; Yannoukakos, Drakoulis; Garber, Judy; Ellis, Steve; Frost, Debra; Platte, Radka; Fineberg, Elena; Evans, Gareth; Lalloo, Fiona; Izatt, Louise; Eeles, Ros; Adlard, Julian; Davidson, Rosemarie; Cole, Trevor; Eccles, Diana; Cook, Jackie; Hodgson, Shirley; Brewer, Carole; Tischkowitz, Marc; Douglas, Fiona; Porteous, Mary; Side, Lucy; Walker, Lisa; Morrison, Patrick; Donaldson, Alan; Kennedy, John; Foo, Claire; Godwin, Andrew K.; Schmutzler, Rita Katharina; Wappenschmidt, Barbara; Rhiem, Kerstin; Engel, Christoph; Meindl, Alfons; Ditsch, Nina; Arnold, Norbert; Plendl, Hans Jörg; Niederacher, Dieter; Sutter, Christian; Wang-Gohrke, Shan; Steinemann, Doris; Preisler-Adams, Sabine; Kast, Karin; Varon-Mateeva, Raymonda; Gehrig, Andrea; Stoppa-Lyonnet, Dominique; Sinilnikova, Olga M.; Mazoyer, Sylvie; Damiola, Francesca; Poppe, Bruce; Claes, Kathleen; Piedmonte, Marion; Tucker, Kathy; Backes, Floor; Rodríguez, Gustavo; Brewster, Wendy; Wakeley, Katie; Rutherford, Thomas; Caldés, Trinidad; Nevanlinna, Heli; Aittomäki, Kristiina; Rookus, Matti A.; van Os, Theo A. M.; van der Kolk, Lizet; de Lange, J. L.; Meijers-Heijboer, Hanne E. J.; van der Hout, A. H.; van Asperen, Christi J.; Gómez Garcia, Encarna B.; Hoogerbrugge, Nicoline; Collée, J. Margriet; van Deurzen, Carolien H. M.; van der Luijt, Rob B.; Devilee, Peter; HEBON; Olah, Edith; Lázaro, Conxi; Teulé, Alex; Menéndez, Mireia; Jakubowska, Anna; Cybulski, Cezary; Gronwald, Jacek; Lubinski, Jan; Durda, Katarzyna; Jaworska-Bieniek, Katarzyna; Johannsson, Oskar Th.; Maugard, Christine; Montagna, Marco; Tognazzo, Silvia; Teixeira, Manuel R.; Healey, Sue; Investigators, kConFab; Olswold, Curtis; Guidugli, Lucia; Lindor, Noralane; Slager, Susan; Szabo, Csilla I.; Vijai, Joseph; Robson, Mark; Kauff, Noah; Zhang, Liying; Rau-Murthy, Rohini; Fink-Retter, Anneliese; Singer, Christian F.; Rappaport, Christine; Geschwantler Kaulich, Daphne; Pfeiler, Georg; Tea, Muy-Kheng; Berger, Andreas; Phelan, Catherine M.; Greene, Mark H.; Mai, Phuong L.; Lejbkowicz, Flavio; Andrulis, Irene; Mulligan, Anna Marie; Glendon, Gord; Toland, Amanda Ewart; Bojesen, Anders; Pedersen, Inge Sokilde; Sunde, Lone; Thomassen, Mads; Kruse, Torben A.; Jensen, Uffe Birk; Friedman, Eitan; Laitman, Yael; Shimon, Shani Paluch; Simard, Jacques; Easton, Douglas F.; Offit, Kenneth; Couch, Fergus J.; Chenevix-Trench, Georgia; Antoniou, Antonis C.; Benitez, Javier

    2014-01-01

    Single Nucleotide Polymorphisms (SNPs) in genes involved in the DNA Base Excision Repair (BER) pathway could be associated with cancer risk in carriers of mutations in the high-penetrance susceptibility genes BRCA1 and BRCA2, given the relation of synthetic lethality that exists between one of the components of the BER pathway, PARP1 (poly ADP ribose polymerase), and both BRCA1 and BRCA2. In the present study, we have performed a comprehensive analysis of 18 genes involved in BER using a tagging SNP approach in a large series of BRCA1 and BRCA2 mutation carriers. 144 SNPs were analyzed in a two stage study involving 23,463 carriers from the CIMBA consortium (the Consortium of Investigators of Modifiers of BRCA1 and BRCA2). Eleven SNPs showed evidence of association with breast and/or ovarian cancer at pgenes for which strongest evidence of association was observed were DNA glycosylases. The strongest evidence was for rs1466785 in the NEIL2 (endonuclease VIII-like 2) gene (HR: 1.09, 95% CI (1.03–1.16), p = 2.7×10−3) for association with breast cancer risk in BRCA2 mutation carriers, and rs2304277 in the OGG1 (8-guanine DNA glycosylase) gene, with ovarian cancer risk in BRCA1 mutation carriers (HR: 1.12 95%CI: 1.03–1.21, p = 4.8×10−3). DNA glycosylases involved in the first steps of the BER pathway may be associated with cancer risk in BRCA1/2 mutation carriers and should be more comprehensively studied. PMID:24698998

  5. Involvement of two endonuclease III homologs in the base excision repair pathway for the processing of DNA alkylation damage in Saccharomyces cerevisiae.

    Science.gov (United States)

    Hanna, Michelle; Chow, Barbara L; Morey, Natalie J; Jinks-Robertson, Sue; Doetsch, Paul W; Xiao, Wei

    2004-01-05

    DNA base excision repair (BER) is initiated by DNA glycosylases that recognize and remove damaged bases. The phosphate backbone adjacent to the resulting apurinic/apyrimidinic (AP) site is then cleaved by an AP endonuclease or glycosylase-associated AP lyase to invoke subsequent BER steps. We have used a genetic approach in Saccharomyces cerevisiae to determine whether or not AP sites are blocks to DNA replication and the biological consequences if AP sites persist in the genome. We previously reported that yeast cells deficient in the two AP endonucleases (apn1 apn2 double mutant) are extremely sensitive to killing by a model DNA alkylating agent methyl methanesulfonate (MMS) and that this sensitivity can be reduced by deleting the MAG1 3-methyladenine DNA glycosylase gene. Here we report that in the absence of the AP endonucleases, deletion of two Escherichia coli endonuclease III homologs, NTG1 and NTG2, partially suppresses MMS-induced killing, which indicates that the AP lyase products are deleterious unless they are further processed by an AP endonuclease. The severe MMS sensitivity seen in AP endonuclease deficient strains can also be rescued by treatment of cells with the AP lyase inhibitor methoxyamine, which suggests that the product of AP lyase action on an AP site is indeed an extremely toxic lesion. In addition to the AP endonuclease interactions, deletion of NTG1 and NTG2 enhances the mag1 mutant sensitivity to MMS, whereas overexpression of MAG1 in either the ntg1 or ntg2 mutant severely affects cell growth. These results help to delineate alkylation base lesion flow within the BER pathway.

  6. Base excision repair of chemotherapeutically-induced alkylated DNA damage predominantly causes contractions of expanded GAA repeats associated with Friedreich's ataxia.

    Science.gov (United States)

    Lai, Yanhao; Beaver, Jill M; Lorente, Karla; Melo, Jonathan; Ramjagsingh, Shyama; Agoulnik, Irina U; Zhang, Zunzhen; Liu, Yuan

    2014-01-01

    Expansion of GAA·TTC repeats within the first intron of the frataxin gene is the cause of Friedreich's ataxia (FRDA), an autosomal recessive neurodegenerative disorder. However, no effective treatment for the disease has been developed as yet. In this study, we explored a possibility of shortening expanded GAA repeats associated with FRDA through chemotherapeutically-induced DNA base lesions and subsequent base excision repair (BER). We provide the first evidence that alkylated DNA damage induced by temozolomide, a chemotherapeutic DNA damaging agent can induce massive GAA repeat contractions/deletions, but only limited expansions in FRDA patient lymphoblasts. We showed that temozolomide-induced GAA repeat instability was mediated by BER. Further characterization of BER of an abasic site in the context of (GAA)20 repeats indicates that the lesion mainly resulted in a large deletion of 8 repeats along with small expansions. This was because temozolomide-induced single-stranded breaks initially led to DNA slippage and the formation of a small GAA repeat loop in the upstream region of the damaged strand and a small TTC loop on the template strand. This allowed limited pol β DNA synthesis and the formation of a short 5'-GAA repeat flap that was cleaved by FEN1, thereby leading to small repeat expansions. At a later stage of BER, the small template loop expanded into a large template loop that resulted in the formation of a long 5'-GAA repeat flap. Pol β then performed limited DNA synthesis to bypass the loop, and FEN1 removed the long repeat flap ultimately causing a large repeat deletion. Our study indicates that chemotherapeutically-induced alkylated DNA damage can induce large contractions/deletions of expanded GAA repeats through BER in FRDA patient cells. This further suggests the potential of developing chemotherapeutic alkylating agents to shorten expanded GAA repeats for treatment of FRDA.

  7. DNA glycosylases involved in base excision repair may be associated with cancer risk in BRCA1 and BRCA2 mutation carriers.

    Science.gov (United States)

    Osorio, Ana; Milne, Roger L; Kuchenbaecker, Karoline; Vaclová, Tereza; Pita, Guillermo; Alonso, Rosario; Peterlongo, Paolo; Blanco, Ignacio; de la Hoya, Miguel; Duran, Mercedes; Díez, Orland; Ramón Y Cajal, Teresa; Konstantopoulou, Irene; Martínez-Bouzas, Cristina; Andrés Conejero, Raquel; Soucy, Penny; McGuffog, Lesley; Barrowdale, Daniel; Lee, Andrew; Swe-Brca; Arver, Brita; Rantala, Johanna; Loman, Niklas; Ehrencrona, Hans; Olopade, Olufunmilayo I; Beattie, Mary S; Domchek, Susan M; Nathanson, Katherine; Rebbeck, Timothy R; Arun, Banu K; Karlan, Beth Y; Walsh, Christine; Lester, Jenny; John, Esther M; Whittemore, Alice S; Daly, Mary B; Southey, Melissa; Hopper, John; Terry, Mary B; Buys, Saundra S; Janavicius, Ramunas; Dorfling, Cecilia M; van Rensburg, Elizabeth J; Steele, Linda; Neuhausen, Susan L; Ding, Yuan Chun; Hansen, Thomas V O; Jønson, Lars; Ejlertsen, Bent; Gerdes, Anne-Marie; Infante, Mar; Herráez, Belén; Moreno, Leticia Thais; Weitzel, Jeffrey N; Herzog, Josef; Weeman, Kisa; Manoukian, Siranoush; Peissel, Bernard; Zaffaroni, Daniela; Scuvera, Giulietta; Bonanni, Bernardo; Mariette, Frederique; Volorio, Sara; Viel, Alessandra; Varesco, Liliana; Papi, Laura; Ottini, Laura; Tibiletti, Maria Grazia; Radice, Paolo; Yannoukakos, Drakoulis; Garber, Judy; Ellis, Steve; Frost, Debra; Platte, Radka; Fineberg, Elena; Evans, Gareth; Lalloo, Fiona; Izatt, Louise; Eeles, Ros; Adlard, Julian; Davidson, Rosemarie; Cole, Trevor; Eccles, Diana; Cook, Jackie; Hodgson, Shirley; Brewer, Carole; Tischkowitz, Marc; Douglas, Fiona; Porteous, Mary; Side, Lucy; Walker, Lisa; Morrison, Patrick; Donaldson, Alan; Kennedy, John; Foo, Claire; Godwin, Andrew K; Schmutzler, Rita Katharina; Wappenschmidt, Barbara; Rhiem, Kerstin; Engel, Christoph; Meindl, Alfons; Ditsch, Nina; Arnold, Norbert; Plendl, Hans Jörg; Niederacher, Dieter; Sutter, Christian; Wang-Gohrke, Shan; Steinemann, Doris; Preisler-Adams, Sabine; Kast, Karin; Varon-Mateeva, Raymonda; Gehrig, Andrea; Stoppa-Lyonnet, Dominique; Sinilnikova, Olga M; Mazoyer, Sylvie; Damiola, Francesca; Poppe, Bruce; Claes, Kathleen; Piedmonte, Marion; Tucker, Kathy; Backes, Floor; Rodríguez, Gustavo; Brewster, Wendy; Wakeley, Katie; Rutherford, Thomas; Caldés, Trinidad; Nevanlinna, Heli; Aittomäki, Kristiina; Rookus, Matti A; van Os, Theo A M; van der Kolk, Lizet; de Lange, J L; Meijers-Heijboer, Hanne E J; van der Hout, A H; van Asperen, Christi J; Gómez Garcia, Encarna B; Hoogerbrugge, Nicoline; Collée, J Margriet; van Deurzen, Carolien H M; van der Luijt, Rob B; Devilee, Peter; Hebon; Olah, Edith; Lázaro, Conxi; Teulé, Alex; Menéndez, Mireia; Jakubowska, Anna; Cybulski, Cezary; Gronwald, Jacek; Lubinski, Jan; Durda, Katarzyna; Jaworska-Bieniek, Katarzyna; Johannsson, Oskar Th; Maugard, Christine; Montagna, Marco; Tognazzo, Silvia; Teixeira, Manuel R; Healey, Sue; Investigators, Kconfab; Olswold, Curtis; Guidugli, Lucia; Lindor, Noralane; Slager, Susan; Szabo, Csilla I; Vijai, Joseph; Robson, Mark; Kauff, Noah; Zhang, Liying; Rau-Murthy, Rohini; Fink-Retter, Anneliese; Singer, Christian F; Rappaport, Christine; Geschwantler Kaulich, Daphne; Pfeiler, Georg; Tea, Muy-Kheng; Berger, Andreas; Phelan, Catherine M; Greene, Mark H; Mai, Phuong L; Lejbkowicz, Flavio; Andrulis, Irene; Mulligan, Anna Marie; Glendon, Gord; Toland, Amanda Ewart; Bojesen, Anders; Pedersen, Inge Sokilde; Sunde, Lone; Thomassen, Mads; Kruse, Torben A; Jensen, Uffe Birk; Friedman, Eitan; Laitman, Yael; Shimon, Shani Paluch; Simard, Jacques; Easton, Douglas F; Offit, Kenneth; Couch, Fergus J; Chenevix-Trench, Georgia; Antoniou, Antonis C; Benitez, Javier

    2014-04-01

    Single Nucleotide Polymorphisms (SNPs) in genes involved in the DNA Base Excision Repair (BER) pathway could be associated with cancer risk in carriers of mutations in the high-penetrance susceptibility genes BRCA1 and BRCA2, given the relation of synthetic lethality that exists between one of the components of the BER pathway, PARP1 (poly ADP ribose polymerase), and both BRCA1 and BRCA2. In the present study, we have performed a comprehensive analysis of 18 genes involved in BER using a tagging SNP approach in a large series of BRCA1 and BRCA2 mutation carriers. 144 SNPs were analyzed in a two stage study involving 23,463 carriers from the CIMBA consortium (the Consortium of Investigators of Modifiers of BRCA1 and BRCA2). Eleven SNPs showed evidence of association with breast and/or ovarian cancer at p<0.05 in the combined analysis. Four of the five genes for which strongest evidence of association was observed were DNA glycosylases. The strongest evidence was for rs1466785 in the NEIL2 (endonuclease VIII-like 2) gene (HR: 1.09, 95% CI (1.03-1.16), p = 2.7 × 10(-3)) for association with breast cancer risk in BRCA2 mutation carriers, and rs2304277 in the OGG1 (8-guanine DNA glycosylase) gene, with ovarian cancer risk in BRCA1 mutation carriers (HR: 1.12 95%CI: 1.03-1.21, p = 4.8 × 10(-3)). DNA glycosylases involved in the first steps of the BER pathway may be associated with cancer risk in BRCA1/2 mutation carriers and should be more comprehensively studied.

  8. [Application of latissimus dorsi flap in different forms in repair of skin and soft tissue defects in lower extremities].

    Science.gov (United States)

    Zhang, Pi-hong; Huang, Xiao-yuan; Long, Jian-hong; Fan, Peng-ju; Ren, Li-cheng; Zeng, Ji-zhang; Xiao, Mu-zhang

    2009-02-01

    To explore repair methods of skin and soft tissue defects in lower extremities with free latissimus dorsi flaps. Forty-two patients with wounds and soft tissue defects in lower extremities, including 4 cases on knee, 22 cases on leg, 15 cases on ankle and foot, 1 case with extensive avulsion from knee to dorsum of foot, were hospitalized in our unit from February 1996 to February 2008. Wounds or soft tissue defects were respectively repaired with latissimus dorsi musculocutaneous flaps, latissimus dorsi muscle flaps, latissimus dorsi perforator flaps with preserved vascular sleeves, 2 double-leaf segmental latissimus dorsi compound flaps after debridement. The flaps ranged from 18 cm x 8 cm to 40 cm x 18 cm in size. The donor sites were covered by skin grafting in 19 cases. All wounds were healed primarily except vascular crisis occurred in 3 cases, partial necrosis of skin at donor site in 2 cases, and graft site (1 case). Follow-up for 3 to 24 months of 31 patients showed: six cases received two-stage plastic operation on account of bulkiness with trouble in wearing shoes, and mild contraction of muscular flap in 3 cases. Latissimus dorsi flap in various forms can be satisfactory for repair of large skin and soft tissue defects in lower extremities.

  9. Delivery of growth factors using a smart porous nanocomposite scaffold to repair a mandibular bone defect.

    Science.gov (United States)

    Liu, Xian; Zhao, Kun; Gong, Tao; Song, Jian; Bao, Chongyun; Luo, En; Weng, Jie; Zhou, Shaobing

    2014-03-10

    Implantation of a porous scaffold with a large volume into the body in a convenient and safe manner is still a challenging task in the repair of bone defects. In this study, we present a porous smart nanocomposite scaffold with a combination of shape memory function and controlled delivery of growth factors. The shape memory function enables the scaffold with a large volume to be deformed into its temporal architecture with a small volume using hot-compression and can subsequently recover its original shape upon exposure to body temperature after it is implanted in the body. The scaffold consists of chemically cross-linked poly(ε-caprolactone) (c-PCL) and hydroxyapatite nanoparticles. The highly interconnected pores of the scaffold were obtained using the sugar leaching method. The shape memory porous scaffold loaded with bone morphogenetic protein-2 (BMP-2) was also fabricated by coating the calcium alginate layer and BMP-2 on the surface of the pore wall. Under both in vitro and in vivo environmental conditions, the porous scaffold displays good shape memory recovery from the compressed shape with deformed pores of 33 μm in diameter to recover its porous shape with original pores of 160 μm in diameter. In vitro cytotoxicity based on the MTT test revealed that the scaffold exhibited good cytocompatibility. The in vivo micro-CT and histomorphometry results demonstrated that the porous scaffold could promote new bone generation in the rabbit mandibular bone defect. Thus, our results indicated that this shape memory porous scaffold demonstrated great potential for application in bone regenerative medicine.

  10. Repair of postinfarct ventricular septal defect and total myocardial revascularization in a case of dextrocardia with situs inversus.

    Science.gov (United States)

    Kuthe, Sachin A; Mohite, Prashant N; Sarangi, Siddharth; Mathews, Sarin; Thingnam, Shyam K; Reddy, Sreenivas

    2011-01-01

    We report a case of an elderly man who suffered an acute myocardial infarction (MI) with the complication of a post-MI ventricular septal defect (VSD). Situs inversus with dextrocardia was diagnosed during the course of hospitalization. Total myocardial revascularization was achieved using saphenous vein conduits. The VSD was approached through the right ventricle and repaired with a polytetrafluoroethylene patch. Although several cases of coronary artery bypass grafting (CABG) in the presence of dextrocardia have been reported in the literature, this is the first case of repair of a post-MI VSD along with CABG.

  11. Repair of large frontal temporal parietal skull defect with digitally reconstructed titanium mesh: a report of 20 cases

    Directory of Open Access Journals (Sweden)

    Gang-ge CHENG

    2013-09-01

    Full Text Available Objective To explore the clinical effect and surgical technique of the repair of large defect involving frontal, temporal, and parietal regions using digitally reconstructed titanium mesh. Methods Twenty patients with large frontal, temporal, and parietal skull defect hospitalized in Air Force General Hospital from November 2006 to May 2012 were involved in this study. In these 20 patients, there were 13 males and 7 females, aged 18-58 years (mean 39 years, and the defect size measured from 7.0cm×9.0cm to 11.5cm×14.0cm (mean 8.5cm×12.0cm. Spiral CT head scan and digital three-dimensional reconstruction of skull were performed in all the patients. The shape and geometric size of skull defect was traced based on the symmetry principle, and then the data were transferred into digital precision lathe to reconstruct a titanium mesh slightly larger (1.0-1.5cm than the skull defect, and the finally the prosthesis was perfected after pruning the border. Cranioplasty was performed 6-12 months after craniotomy using the digitally reconstructed titanium mesh. Results The digitally reconstructed titanium mesh was used in 20 patients with large frontal, temporal, parietal skull defect. The surgical technique was relatively simple, and the surgical duration was shorter than before. The titanium mesh fit to the defect of skull accurately with satisfactory molding effect, good appearance and symmetrical in shape. No related complication was found in all the patients. Conclusion Repair of large frontal, temporal, parietal skull defect with digitally reconstructed titanium mesh is more advantageous than traditional manual reconstruction, and it can improve the life quality of patients.

  12. MR imaging after rotator cuff repair: full-thickness defects and bursitis-like subacromial abnormalities in asymptomatic subjects.

    Science.gov (United States)

    Zanetti, M; Jost, B; Hodler, J; Gerber, C

    2000-06-01

    To determine the prevalence and extent of residual defects or retears and bursitis-like subacromial abnormalities on MR images after rotator cuff repair in asymptomatic subjects, and to define the clinical relevance of these findings. Fourteen completely asymptomatic patients and 32 patients with residual symptoms were investigated 27-53 months (mean 39 months) after open transosseous reinsertion of the rotator cuff. Coronal T2-weighted turbo spin-echo and turbo STIR or T2-weighted fat-suppressed MR images were obtained. The prevalence and extent of residual defects or retears of the rotator cuff and bursitis-like subacromial abnormalities were determined. Residual defects or retears were detected in three (21%) and bursitis-like abnormalities in 14 (100%) of the 14 asymptomatic patients. Fifteen (47%) residual defects or retears and 31 (97%) bursitis-like abnormalities were diagnosed in the 32 patients with residual symptoms. The size of the residual defects/retears was significantly smaller in the asymptomatic group (mean 8 mm, range 6-11 mm) than in the symptomatic group (mean 32 mm, range 7-50 mm) (t-test, P = 0.001). The extent of the bursitis-like subacromial abnormalities did not significantly differ (t-test, P > 0.05) between asymptomatic (mean 28 x 3 mm) and symptomatic patients (mean 32 x 3 mm). Small residual defects or retears (Subacromial bursitis-like MR abnormalities are almost always seen after rotator cuff repair even in patients without residual complaints. They may persist for several years after rotator cuff repair and appear to be clinically irrelevant.

  13. MR imaging after rotator cuff repair: full-thickness defects and bursitis-like subacromial abnormalities in asymptomatic subjects

    Energy Technology Data Exchange (ETDEWEB)

    Zanetti, M.; Hodler, J. [Dept. of Radiology, University Hospital Balgrist, Zurich (Switzerland); Jost, B.; Gerber, C. [Dept. of Orthopedic Surgery, University Hospital Balgrist, Zurich (Switzerland)

    2000-06-01

    Objective. To determine the prevalence and extent of residual defects or retears and bursitis-like subacromial abnormalities on MR images after rotator cuff repair in asymptomatic subjects, and to define the clinical relevance of these findings.Design and patients. Fourteen completely asymptomatic patients and 32 patients with residual symptoms were investigated 27-53 months (mean 39 months) after open transosseous reinsertion of the rotator cuff. Coronal T2-weighted turbo spin-echo and turbo STIR or T2-weighted fat-suppressed MR images were obtained. The prevalence and extent of residual defects or retears of the rotator cuff and bursitis-like subacromial abnormalities were determined.Results. Residual defects or retears were detected in three (21%) and bursitis-like abnormalities in 14 (100%) of the 14 asymptomatic patients. Fifteen (47%) residual defects or retears and 31 (97%) bursitis-like abnormalities were diagnosed in the 32 patients with residual symptoms. The size of the residual defects/retears was significantly smaller in the asymptomatic group (mean 8 mm, range 6-11 mm) than in the symptomatic group (mean 32 mm, range 7-50 mm) (t-test, P=0.001). The extent of the bursitis-like subacromial abnormalities did not significantly differ (t-test, P>0.05) between asymptomatic (mean 28 x 3 mm) and symptomatic patients (mean 32 x 3 mm).Conclusion. Small residual defects or retears (<1 cm) of the rotator cuff are not necessarily associated with clinical symptoms. Subacromial bursitis-like MR abnormalities are almost always seen after rotator cuff repair even in patients without residual complaints. They may persist for several years after rotator cuff repair and appear to be clinically irrelevant. (orig.)

  14. Thiol-acrylate nanocomposite foams for critical size bone defect repair: A novel biomaterial.

    Science.gov (United States)

    Garber, Leah; Chen, Cong; Kilchrist, Kameron V; Bounds, Christopher; Pojman, John A; Hayes, Daniel

    2013-12-01

    Bone tissue engineering approaches using polymer/ceramic composites show promise as effective biocompatible, absorbable, and osteoinductive materials. A novel class of in situ polymerizing thiol-acrylate based copolymers synthesized via an amine-catalyzed Michael addition was studied for its potential to be used in bone defect repair. Both pentaerythritol triacrylate-co-trimethylolpropane tris(3-mercaptopropionate) (PETA-co-TMPTMP) and PETA-co-TMPTMP with hydroxyapatite (HA) composites were fabricated in solid cast and foamed forms. These materials were characterized chemically and mechanically followed by an in vitro evaluation of the biocompatibility and chemical stability in conjunction with human adipose-derived mesenchymal pluripotent stem cells (hASC). The solid PETA-co-TMPTMP with and without HA exhibited compressive strength in the range of 7-20 MPa, while the cytotoxicity and biocompatibility results demonstrate higher metabolic activity of hASC on PETA-co-TMPTMP than on a polycaprolactone control. Scanning electron microscope imaging of hASC show expected spindle shaped morphology when adhered to copolymer. Micro-CT analysis indicates open cell interconnected pores. Foamed PETA-co-TMPTMP HA composite shows promise as an alternative to FDA-approved biopolymers for bone tissue engineering applications. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  15. Repair of damaged DNA in vivo: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Hanawalt, P.C.

    1987-09-01

    This contract was initiated in 1962 with the US Atomic Energy Commission to carry out basic research on the effects of radiation on the process of DNA replication in bacteria. Within the first contract year we discovered repair replication at the same time that Setlow and Carrier discovered pyrimidine dimer excision. These discoveries led to the elucidation of the process of excision-repair, one of the most important mechanisms by which living systems, including humans, respond to structural damage in their genetic material. We improved methodology for distinguishing repair replication from semiconservative replication and instructed others in these techniques. Painter then was the first to demonstrate repair replication in ultraviolet irradiated human cells. He, in turn, instructed James Cleaver who discovered that skin fibroblasts from patients with xeroderma pigmentosum were defective in excision-repair. People with this genetic defect are extremely sensitive to sunlight and they develop carcinomas and melanomas of the skin with high frequency. The existence of this hereditary disease attests to the importance of DNA repair in man. We certainly could not survive in the normal ultraviolet flux from the sun if our DNA were not continuously monitored for damage and repaired. Other hereditary diseases such as ataxia telangiectasia, Cockayne's syndrome, Blooms syndrome and Fanconi's anemia also involve deficiencies in DNA damage processing. The field of DNA repair has developed rapidly as we have learned that most environmental chemical carcinogens as well as radiation produce repairable damage in DNA. 251 refs.

  16. The Cockayne syndrome B protein, involved in transcription-coupled repair resides in a RNA polymerase II-containing complex.

    NARCIS (Netherlands)

    A.J. van Gool (Alain); E. Citterio (Elisabetta); S. Rademakers (Suzanne); R. van Os; W. Vermeulen (Wim); A. Constantinou; J-M. Egly (Jean-Marc); D. Bootsma (Dirk); J.H.J. Hoeijmakers (Jan)

    1997-01-01

    textabstractTranscription-coupled repair (TCR), a subpathway of nucleotide excision repair (NER) defective in Cockayne syndrome A and B (CSA and CSB), is responsible for the preferential removal of DNA lesions from the transcribed strand of active genes, permitting rapid resumption of blocked

  17. Anti-tumour compounds illudin S and Irofulven induce DNA lesions ignored by global repair and exclusively processed by transcription- and replication-coupled repair pathways.

    OpenAIRE

    Raams, Anja; Kelner, Michael; Ng, Jessica; Yamashita, Yukiko; Takeda, Shiunichi; McMorris, Trevor; Hoeijmakers, Jan; Jaspers, Nicolaas

    2002-01-01

    textabstractIlludin S is a natural sesquiterpene drug with strong anti-tumour activity. Inside cells, unstable active metabolites of illudin cause the formation of as yet poorly characterised DNA lesions. In order to identify factors involved in their repair, we have performed a detailed genetic survey of repair-defective mutants for responses to the drug. We show that 90% of illudin's lethal effects in human fibroblasts can be prevented by an active nucleotide excision repair (NER) system. C...

  18. 59. Early and late results of routine leaflet augmentation for complete atrio-ventricular septal defect repair

    Directory of Open Access Journals (Sweden)

    A. Arifi

    2016-07-01

    Full Text Available Complete AVSD (CAVSD is characterized by the presence of a common atrio-ventricular (AV orifice, an inter-atrial communication, and a ventricular septal defect (VSD. Results of surgical correction of atrio-ventricular septal defects (AVSDs have improved over the last decades; however, the need for reoperation for left atrio-ventricular valve regurgitation, after primary AVSD repair remains a major concern. The aim of our study is to assess the outcome of the routine leaflet augmentation technique in CAVSD repair. A retrospective database and chart review analysis of all patients who underwent AV canal repair at king Abdul-Aziz Cardiac Center during period from 1999 to September 2014 was conducted. Demographic data, associated anomalies, operative data, ICU and hospital course were reviewed. Early outcomes were reviewed for postoperative complications (Chylothorax, complete AV block, Arrhythmias, early mortality and late outcomes were reviewed for Left AV valve regurgitation requiring for re-intervention and late mortality. Two hundred and sixty patients underwent leaflet augmentation technique to repair complete AVSD, between January 1999 and September 2014. The mean age was (131.5 months, and mean weight (6.06 kg. A variety of concomitant procedures were performed at the time of repair of the CAVSD, including a total of 49 patients (18.8% who underwent PDA ligation. Repair of TV (Right AV valve was performed in 11 patients (4.2%, 9 patients (3.46% required RVOTO resection, in 5 patients (1.92%, PA plasty was done and 2 patients (0.76% required ECMO after CAVSD repair. Regarding reoperations, a total of 17 patients (of 260 required reoperation after initial CAVSD repair. The most common indication for reoperation was left AV valve regurgitation in 16 patients (6% in the follow up period up to 15 years. One patient (0.38% required diaphragmatic plication. The overall mortality was 3 patients (1.1%. Leaflet augmentation for the repair of the

  19. Telomeric Allelic Imbalance Indicates Defective DNA Repair and Sensitivity to DNA-Damaging Agents

    DEFF Research Database (Denmark)

    Birkbak, Nicolai J.; Wang, Zhigang C.; Kim, Ji-Young

    2012-01-01

    DNA repair competency is one determinant of sensitivity to certain chemotherapy drugs, such as cisplatin. Cancer cells with intact DNA repair can avoid the accumulation of genome damage during growth and also can repair platinum-induced DNA damage. We sought genomic signatures indicative of defec...

  20. The Effect of Sodium Hyaluronate on Ligamentation and Biomechanical Property of Tendon in Repair of Achilles Tendon Defect with Polyethylene Terephthalate Artificial Ligament: A Rabbit Tendon Repair Model

    Directory of Open Access Journals (Sweden)

    Shengkun Li

    2016-01-01

    Full Text Available The Achilles tendon is the most common ruptured tendon of human body. Reconstruction with polyethylene terephthalate (PET artificial ligament is recommended in some serious cases. Sodium hyaluronate (HA is beneficial for the healing of tendon injuries. We aimed to determine the effect of sodium hyaluronate in repair of Achilles tendon defect with PET artificial ligament in an animal tendon repair model. Sixteen New Zealand White rabbits were divided into two groups. Eight rabbits repaired with PET were assigned to PET group; the other eight rabbits repaired with PET along with injection of HE were assigned to HA-PET group. All rabbits were sacrificed at 4 and 8 weeks postoperatively for biomechanical and histological examination. The HA-PET group revealed higher biomechanical property compared with the PET group. Histologically, more collagen tissues grew into the HA-PET group compared with PET group. In conclusion, application of sodium hyaluronate can improve the healing of Achilles tendon reconstruction with polyethylene terephthalate artificial ligament.

  1. Closure versus non-closure of fascial defects in laparoscopic ventral and incisional hernia repairs: a review of the literature.

    Science.gov (United States)

    Suwa, Katsuhito; Okamoto, Tomoyoshi; Yanaga, Katsuhiko

    2016-07-01

    The laparoscopic technique for repairing ventral and incisional hernias (VIH) is now well established. However, several issues related to laparoscopic VIH repair, such as the high recurrence rate for hernias with large fascial defects and in extremely obese patients, are yet to be resolved. Additional problems include seroma formation, mesh bulging/eventration, and non-restoration of the abdominal wall rigidity/function with only bridging of the hernial orifice using standard laparoscopic intraperitoneal onlay mesh repair (sIPOM). To solve these problems, laparoscopic fascial defect closure with IPOM reinforcement (IPOM-Plus) has been introduced in the past decade, and a few studies have reported satisfactory outcomes. Although detailed techniques for fascial defect closure and handling of the mesh have been published, standardized techniques are yet to be established. We reviewed the literature on IPOM-Plus in the PubMed database and identified 16 reports in which the recurrence rate, incidence of seroma formation, and incidence of mesh bulging were 0-7.7, 0-11.4, and 0 %, respectively. Several comparison studies between sIPOM and IPOM-Plus seem to suggest that IPOM-Plus is associated with more favorable surgical outcomes; however, larger-scale studies are essential.

  2. Closure of a direct inguinal hernia defect in laparoscopic repair with barbed suture: a simple method to prevent seroma formation?

    Science.gov (United States)

    Li, Junsheng; Zhang, Weiyu

    2018-02-01

    Seroma is a frequent postoperative complication after laparoscopic direct inguinal hernia repair (both in TAPP and TEP). There are several methods to address this problem; however, these techniques are not without problems. The purpose of this study was to introduce and evaluate a new technique to address this problem. This is a prospective study of consecutive patients. All patients diagnosed with direct inguinal hernias eligible for laparoscopic repair were included. A single surgeon performed all the included operations. During laparoscopic inguinal hernia repair (TAPP or TEP), we closed the direct hernia defect with barbed sutures around the transversalis fascia, inverted the apex of the attenuated transversalis fascia, and sutured it at the base to completely eradicate the defect cavity. Prosthetic mesh was not additionally fixed in all patients. The primary postoperative outcome parameter was seroma formation, and secondary outcome parameters included groin pain, surgical complications, and hernia recurrence. Twenty-five male patients with 36 sides of direct hernias were included in this study, and all procedures were carried out laparoscopically and successfully. Only one patient developed significant seroma, which resolved 1 month later. The early postoperative pain was minimal, and no recurrence and chronic pain occurred during the follow-up period (4-13 months). The present direct inguinal hernia defect closing technique with barbed suture is a simple, easily reproducible, and effective method for the prevention of seroma formation.

  3. Repair of Osteochondral Defects Using Human Umbilical Cord Wharton's Jelly-Derived Mesenchymal Stem Cells in a Rabbit Model

    Science.gov (United States)

    Jia, Yanhui; Yuan, Mei; Guo, Weimin; Huang, Jingxiang; Zhao, Bin; Xu, Wenjing; Lu, Shibi

    2017-01-01

    Umbilical cord Wharton's jelly-derived mesenchymal stem cell (WJMSC) is a new-found mesenchymal stem cell in recent years with multiple lineage potential. Due to its abundant resources, no damage procurement, and lower immunogenicity than other adult MSCs, WJMSC promises to be a good xenogenous cell candidate for tissue engineering. This in vivo pilot study explored the use of human umbilical cord Wharton's jelly mesenchymal stem cells (hWJMSCs) containing a tissue engineering construct xenotransplant in rabbits to repair full-thickness cartilage defects in the femoral patellar groove. We observed orderly spatial-temporal remodeling of hWJMSCs into cartilage tissues during repair over 16 months, with characteristic architectural features, including a hyaline-like neocartilage layer with good surface regularity, complete integration with adjacent host cartilage, and regenerated subchondral bone. No immune rejection was detected when xenograft hWJMSCs were implanted into rabbit cartilage defects. The repair results using hWJMSCs were superior to those of chondrogenically induced hWJMSCs after assessing gross appearance and histological grading scores. These preliminary results suggest that using novel undifferentiated hWJMSCs as seed cells might be a better approach than using transforming growth factor-β-induced differentiated hWJMSCs for in vivo tissue engineering treatment of cartilage defects. hWJMSC allografts may be promising for clinical applications. PMID:28261617

  4. [Repair of large and deep skin and soft tissue defects around the knee joints with free latissimus dorsi musculocutaneous flaps].

    Science.gov (United States)

    Zhang, Minghua; Cui, Xu; Zeng, Jizhang; Liu, Xiong; Huang, Mitao; Zhang, Pihong; Huang, Xiaoyuan

    2015-10-01

    To investigate the clinical efficacy of free latissimus dorsi musculocutaneous flaps in repairing large and deep skin and soft tissue defects around the knee joints. Twenty-five patients with large and deep skin and soft tissue defects around the knee joints were hospitalized from March 2005 to March 2014. The area of defects around the knee joints ranged from 10 cm × 8 cm to 43 cm × 23 cm. The free latissimus dorsi musculocutaneous flaps were used to repair the defects, with the area ranging from 12 cm × 10 cm to 45 cm × 25 cm. The thoracodorsal artery and its concomitant vein of the musculocutaneous flap were anastomosed to the descending branch of the lateral circumflex femoral artery and its concomitant vein respectively to reconstruct blood supply. Split-thickness skin grafts around the flap donor sites were harvested to cover the muscle surface of the musculocutaneous flaps. The flap donor sites were closed directly with suture, and the skin donor sites were healed by dressing change. All the 25 flaps survived without vascular crisis. The flaps were in satisfactory appearance. The flap donor sites were healed with linear scar. All the patients were followed up for 3 to 6 months. At last, they were able to stand up and walk. The free latissimus dorsi musculocutaneous flap transplantation is an effective treatment for the repair of large and deep soft tissue defects around the knee joints, and the descending branch of lateral circumflex femoral artery and its concomitant vein are the appropriate recipient vessels.

  5. Factors associated with moderate or severe left atrioventricular valve regurgitation within 30 days of repair of complete atrioventricular septal defect

    Directory of Open Access Journals (Sweden)

    Marcelo Felipe Kozak

    2015-09-01

    Full Text Available AbstractIntroduction:Left atrioventricular valve regurgitation is the most concerning residual lesion after surgical correction of atrioventricular septal defects.Objective:To determine factors associated with moderate or severe left atrioventricular valve regurgitation within 30 days of surgical repair of complete atrioventricular septal defect.Methods:We assessed the results of 53 consecutive patients 3 years-old and younger presenting with complete atrioventricular septal defect that were operated on at our practice between 2002 and 2010. The following variables were considered: age, weight, absence of Down syndrome, grade of preoperative atrioventricular valve regurgitation, abnormalities on the left atrioventricular valve and the use of annuloplasty. Median age was 6.7 months; median weight was 5.3 Kg; 86.8% had Down syndrome. At the time of preoperative evaluation, there were 26 cases with moderate or severe left atrioventricular valve regurgitation (49.1%. Abnormalities on the left atrioventricular valve were found in 11.3%; annuloplasty was performed in 34% of the patients.Results:At the time of postoperative evaluation, there were 21 cases with moderate or severe left atrioventricular valve regurgitation (39.6%. After performing a multivariate analysis, the only significant factor associated with moderate or severe left atrioventricular valve regurgitation was the absence of Down syndrome (P=0.03.Conclusion:Absence of Down syndrome was associated with moderate or severe postoperative left atrioventricular valve regurgitation after surgical repair of complete atrioventricular septal defect at our practice.

  6. Two Stage Repair of Composite Craniofacial Defects with Antibiotic Releasing Porous Poly(methyl methacrylate) Space Maintainers and Bone Regeneration

    Science.gov (United States)

    Spicer, Patrick

    Craniofacial defects resulting from trauma and resection present many challenges to reconstruction due to the complex structure, combinations of tissues, and environment, with exposure to the oral, skin and nasal mucosal pathogens. Tissue engineering seeks to regenerate the tissues lost in these defects; however, the composite nature and proximity to colonizing bacteria remain difficult to overcome. Additionally, many tissue engineering approaches have further hurdles to overcome in the regulatory process to clinical translation. As such these studies investigated a two stage strategy employing an antibiotic-releasing porous polymethylmethacrylate space maintainer fabricated with materials currently part of products approved or cleared by the United States Food and Drug Administration, expediting the translation to the clinic. This porous space maintainer holds the bone defect open allowing soft tissue to heal around the defect. The space maintainer can then be removed and one regenerated in the defect. These studies investigated the individual components of this strategy. The porous space maintainer showed similar soft tissue healing and response to non-porous space maintainers in a rabbit composite tissue defect. The antibiotic-releasing space maintainers showed release of antibiotics from 1-5 weeks, which could be controlled by loading and fabrication parameters. In vivo, space maintainers releasing a high dose of antibiotics for an extended period of time increased soft tissue healing over burst release space maintainers in an infected composite tissue defect model in a rabbit mandible. Finally, stabilization of bone defects and regeneration could be improved through scaffold structures and delivery of a bone forming growth factor. These studies illustrate the possibility of the two stage strategy for repair of composite tissue defects of the craniofacial complex.

  7. Clinicopathologic Significance of Mismatch Repair Defects in Endometrial Cancer: An NRG Oncology/Gynecologic Oncology Group Study.

    Science.gov (United States)

    McMeekin, D Scott; Tritchler, David L; Cohn, David E; Mutch, David G; Lankes, Heather A; Geller, Melissa A; Powell, Matthew A; Backes, Floor J; Landrum, Lisa M; Zaino, Richard; Broaddus, Russell D; Ramirez, Nilsa; Gao, Feng; Ali, Shamshad; Darcy, Kathleen M; Pearl, Michael L; DiSilvestro, Paul A; Lele, Shashikant B; Goodfellow, Paul J

    2016-09-01

    The clinicopathologic significance of mismatch repair (MMR) defects in endometrioid endometrial cancer (EEC) has not been definitively established. We undertook tumor typing to classify MMR defects to determine if MMR status is prognostic or predictive. Primary EECs from NRG/GOG0210 patients were assessed for microsatellite instability (MSI), MLH1 methylation, and MMR protein expression. Each tumor was assigned to one of four MMR classes: normal, epigenetic defect, probable mutation (MMR defect not attributable to MLH1 methylation), or MSI-low. The relationships between MMR classes and clinicopathologic variables were assessed using contingency table tests and Cox proportional hazard models. A total of 1,024 tumors were assigned to MMR classes. Epigenetic and probable mutations in MMR were significantly associated with higher grade and more frequent lymphovascular space invasion. Epigenetic defects were more common in patients with higher International Federation of Gynecology and Obstetrics stage. Overall, there were no differences in outcomes. Progression-free survival was, however, worse for women whose tumors had epigenetic MMR defects compared with the MMR normal group (hazard ratio, 1.37; P < .05; 95% CI, 1.00 to 1.86). An exploratory analysis of interaction between MMR status and adjuvant therapy showed a trend toward improved progression-free survival for probable MMR mutation cases. MMR defects in EECs are associated with a number of well-established poor prognostic indicators. Women with tumors that had MMR defects were likely to have higher-grade cancers and more frequent lymphovascular space invasion. Surprisingly, outcomes in these patients were similar to patients with MMR normal tumors, suggesting that MMR defects may counteract the effects of negative prognostic factors. Altered immune surveillance of MMR-deficient tumors, and other host/tumor interactions, is likely to determine outcomes for patients with MMR-deficient tumors. © 2016 by American

  8. Isotretinoin effect on the repair of bone defects - a study in rat calvaria.

    Science.gov (United States)

    de Oliveira, Henrique T R; Bergoli, Roberta D; Hirsch, Wâneza D B; Chagas, Otacílio L; Heitz, Cláiton; Silva, Daniela N

    2013-10-01

    Isotretinoin is a vitamin A derivative, indicated for the treatment of patients with severe acne, which shows several side effects on bone metabolism. This study analyzed the process of bone repair in rats receiving 7.5 mg/kg/day of oral isotretinoin. Thirty-three male albino Wistar rats, at approximately 60 days of age, were randomly assigned to control (n = 15) and experimental (n = 18) groups. Only the experimental group underwent oral isotretinoin therapy. In both groups, a 2-mm cavity was established in the calvarium of each animal. The animals were euthanize 21, 28 and 90 days postoperatively. The parietal bone was removed and the surgical specimens underwent histological examination. Computed histomorphometry allowed the measurement of the total area of bone defects and the proportion of newly formed bone at the different observation time points. In the experimental group, the results, expressed as mean percentage of newly formed bone, were: 25.37% (±9.14) at day 21; 41.78% (±7.00) at day 28; and 57.51% (±11.62) at day 90. In the control group, the results were: 17.10% (±9.23) at day 21; 34.42% (±7.70) at day 28; and 48.49% (±16.40) at day 90. These results enabled us to conclude that isotretinoin promoted acceleration in the process of new bone formation in rat calvaria, although this increase was not statistically significant. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  9. Segmentation, surface rendering, and surface simplification of 3-D skull images for the repair of a large skull defect

    Science.gov (United States)

    Wan, Weibing; Shi, Pengfei; Li, Shuguang

    2009-10-01

    Given the potential demonstrated by research into bone-tissue engineering, the use of medical image data for the rapid prototyping (RP) of scaffolds is a subject worthy of research. Computer-aided design and manufacture and medical imaging have created new possibilities for RP. Accurate and efficient design and fabrication of anatomic models is critical to these applications. We explore the application of RP computational methods to the repair of a pediatric skull defect. The focus of this study is the segmentation of the defect region seen in computerized tomography (CT) slice images of this patient's skull and the three-dimensional (3-D) surface rendering of the patient's CT-scan data. We see if our segmentation and surface rendering software can improve the generation of an implant model to fill a skull defect.

  10. Repair of segmental radial defect with autologous bone marrow aspirate and hydroxyapatite in rabbit radius: A clinical and radiographic evaluation

    Directory of Open Access Journals (Sweden)

    Kalbaza Ahmed Yassine

    2017-07-01

    Full Text Available Aim: Finding an ideal bone substitute to treat large bone defects, delayed union and nonunions remain a challenge for orthopedic surgeons and researchers. Several studies have been conducted on bone regeneration; each has its own advantages and disadvantages. The aim of this study was to evaluate the effect of a combination of hydroxyapatite (HA powder with autologous bone marrow (BM aspirate on the repair of segmental radial defect in a rabbit model. Materials and Methods: A total of 36 male and adult New Zealand rabbit with a mean weight of 2.25 kg were used in this study. Approximately, 5 mm defect was created in the mid-shaft of the radius to be filled with HA powder in the control group "HA" (n=18 and with a combination of HA powder and autologous BM aspirate in the test group "HA+BM" (n=18. Animals were observed daily for healing by inspection of the surgical site, and six rabbits of each group were sacrificed at 30, 60, and 90 post-operative days to perform a radiographic evaluation of defect site. Results: Obtained results revealed a better and more rapid bone regeneration in the test group: Since the defect was rapidly and completely filled with mature bone tissue after 90 days. Conclusion: Based on these findings, we could infer that adding a BM aspirate to HA is responsible of a better regeneration process leading to a complete filling of the defect.

  11. Success of Maxillary Alveolar Defect Repair in Rats Using Osteoblast-Differentiated Human Deciduous Dental Pulp Stem Cells.

    Science.gov (United States)

    Jahanbin, Arezoo; Rashed, Roozbeh; Alamdari, Daryoush Hamidi; Koohestanian, Niloufar; Ezzati, Atefeh; Kazemian, Mojgan; Saghafi, Shadi; Raisolsadat, Mohammad Ali

    2016-04-01

    The use of cell-based therapies represents one of the most advanced methods for enhancing the regenerative response in craniofacial abnormalities. The main aim of this study was to evaluate the regenerative potential of human dental pulp stem cells, isolated from deciduous teeth, for reconstructing maxillary alveolar defects in Wistar rats. Human deciduous dental pulp stem cells were isolated and stimulated to differentiate into osteoblasts in culture media. Maxillary alveolar defects were created in 60 Wistar rats by a surgical procedure. Then, on the basis of the type of graft used to repair the bone defect, the rats were divided into 6 equal groups: groups 1 and 2, transplantation of iliac bone graft; groups 3 and 4, transplantation of stem cells derived from deciduous dental pulp in addition to collagen matrix; groups 5 and 6, transplantation of just collagen matrix. Then, fetal bone formation, granulation tissue, fibrous tissue, and inflammatory tissue were evaluated by hematoxylin-eosin staining at 1 month (groups 1, 3, and 5) and 2 months (groups 2, 4, and 6) after surgery, and data were analyzed and compared using the Fisher exact test. Maximum fetal bone formation occurred in group 2, in which iliac bone graft was inserted into the defect area for 2 months; there also were significant differences among the groups for bone formation (P = .009). In the 1-month groups, there were no significant differences between the control and stem cell-plus-scaffold groups. There were significant differences between the 2-month groups for fetal bone formation only between the control and scaffold groups (P = .026). The study showed that human dental pulp stem cells are an additional cell resource for repairing maxillary alveolar defects in rats and constitute a promising model for reconstruction of human maxillary alveolar defects in patients with cleft lip and palate. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc

  12. Defective repair of 5-hydroxy-2'-deoxycytidine in Cockayne syndrome cells and its complementation by Escherichia coli formamidopyrimidine DNA glycosylase and endonuclease III.

    Science.gov (United States)

    Foresta, Mara; Ropolo, Monica; Degan, Paolo; Pettinati, Ilaria; Kow, Yoke W; Damonte, Gianluca; Poggi, Alessandro; Frosina, Guido

    2010-03-01

    Repair of the oxidized purine 8-oxo-7,8-dihydro-2'-deoxyguanosine is inefficient in cells belonging to both complementation groups A and B of Cockayne syndrome (CS), a developmental and neurological disorder characterized by defective transcription-coupled repair. We show here that both CS-A and CS-B cells are also defective in the repair of 5-hydroxy-2'-deoxycytidine (5-OHdC), an oxidized pyrimidine with cytotoxic and mutagenic properties. The defect in the repair of oxidatively damaged DNA in CS cells thus extends to oxidized pyrimidines, indicating a general flaw in the repair of oxidized lesions in this syndrome. The defect could not be reproduced in in vitro repair experiments on oligonucleotide substrates, suggesting a role for both CS-A and CS-B proteins in chromatin remodeling during 5-OHdC repair. Expression of Escherichia coli formamidopyrimidine DNA glycosylase (FPG) or endonuclease III complemented the 5-OHdC repair deficiency. Hence, the expression of a single enzyme, FPG from E. coli, stably corrects the delayed removal of both oxidized purines and oxidized pyrimidines in CS cells. (c) 2009 Elsevier Inc. All rights reserved.

  13. POROUS POLYMER IMPLANTS FOR REPAIR OF FULL-THICKNESS DEFECTS OF ARTICULAR-CARTILAGE - AN EXPERIMENTAL-STUDY IN RABBIT AND DOG

    NARCIS (Netherlands)

    JANSEN, HWB; VETH, RPH; NIELSEN, HKL; DEGROOT, JH; PENNINGS, AJ

    1992-01-01

    Full-thickness defects of articular cartilage were repaired by implantation of porous polymer implants in rabbits and dogs. The quality of the repair tissue was determined by collagen typing with antibodies. Implants with varying pore sizes and chemical composition were used. The effect of loading

  14. Robotically assisted totally endoscopic atrial septal defect repair: insights from operative times, learning curves, and clinical outcome.

    Science.gov (United States)

    Bonaros, Nikolaos; Schachner, Thomas; Oehlinger, Armin; Ruetzler, Elisabeth; Kolbitsch, Christian; Dichtl, Wolfgang; Mueller, Silvana; Laufer, Guenther; Bonatti, Johannes

    2006-08-01

    Remote access perfusion and robotics have enabled totally endoscopic closure of atrial septal defect and patent foramen ovale. The aim of this study was to address learning curve issues of totally endoscopic atrial septal defect repair on the basis of a single-center experience and to investigate whether long cardiopulmonary bypass and aortic occlusion times influence intraoperative and postoperative outcomes. Seventeen patients (median age, 35 years; range, 16 to 55 years) underwent totally endoscopic atrial septal defect repair using remote access perfusion and robotic technology (da Vinci telemanipulation system). Learning curves were assessed by means of regression analysis with logarithmic curve fit. The effect of operative variables on clinical outcome was analyzed by linear regression using the Spearman's rho coefficient. No operative mortality or serious surgical complications were observed. No residual shunt was detected at intraoperative or postoperative echocardiography. Significant learning curves were noted for total operative time: y(min) = 406 - 49 ln(x) (r2 = 0.725; p = 0.002); cardiopulmonary bypass time: y(min) = 225 - 42 ln(x) (r2 = 0.699; p = 0.003); and aortic occlusion time: y(min) = 117 - 25 ln(x) (r2 = 0.517; p = 0.04), x = number of procedures. Median ventilation time, intensive care unit stay, and hospital length of stay were 7 hours (range, 2 to 19 hours), 26 hours (range, 15 to 120 hours), and 8 days (range, 5 to 14 days), respectively. No correlation was detected between cardiopulmonary bypass time and intubation time (r2 = 0.283; p = 0.326), intensive care unit stay (r2 = -0.138; p = 0.639), or total length of stay (r2 = 0.013; p = 0.962). Totally endoscopic atrial septal defect repair can be performed safely, and learning curves for operative times are steep. Longer cardiopulmonary bypass times had no negative impact on intraoperative and postoperative outcome.

  15. [One-stage repair of pharyngeal defect using tongue flaps after resection of advanced stage hypopharyngeal neoplasm and laryngeal neoplasm].

    Science.gov (United States)

    Han, Yuefeng; Chen, Deshang; Li, Hui; Zhang, Mingjie; Ma, Shiyin; Zhou, Lanzhu

    2012-10-01

    To study the effectiveness of one-stage repairing pharyngeal defect with the tongue flaps after resection of advanced stage hypopharyngeal neoplasm and laryngeal neoplasm. Between June 2006 and March 2011, 20 patients with hypopharyngeal neoplasm (8 cases) and laryngeal neoplasm (12 cases) with advanced stage were treated. There were 19 males and 1 female, aged 47-78 years (mean, 62.8 years). All neoplasms were squamous cell carcinomas. The disease duration was 1-8.5 months (mean, 3.9 months). According to the standards of International Union Against Cancer (UICC, 1987), 12 cases were in stage III and 8 cases were in stage IV. The size of pharyngeal defect was 5 cm x 2 cm to 4 cm x 4 cm after resection of tumor. Defects were repaired by the whole base of the tongue flaps in 16 cases and by the horizontal base of the tongue flaps in 4 cases. The size of the flaps ranged from 5 cm x 2 cm to 4 cm x 4 cm. Postoperative radiotherapy and chemotherapy were regularly performed. The 20 tongue flaps were alive. Healing of incision by first intention was achieved in 18 cases and delayed healing in 2 cases because of subcutaneous fluid. The patients were followed up 12-63 months (mean, 36.7 months). The patients had normal feeding ability and tongue function. Of 20 cases, 12 died and 1 of local recurrence was alive with tumor. The 3-year survival rate was 69.2% (9/13). One-stage repair of pharyngeal defect with the tongue flaps after resection of hypopharyngeal neoplasm and laryngeal neoplasm can obtain good effectiveness because the tongue flap is easy-to-obtain and easy-to-survive, and has abundant blood supply.

  16. [Tricaicium phosphate complex pre-loaded with bone morphogenetic protein-2 or platelet derived growth factor-BB for repairing critical-size cranial defects in SD rats].

    Science.gov (United States)

    He, Rui-Xuan; Xiao, Jian-Bin; Song, Bing; Huang, Zhi-Hui; Zhao, Liang

    2016-03-01

    To observe the effect of a new biomaterial in promoting the bone regeneration for repairing critical-size cranial defects in SD rats. Critical-size cranial defects were induced in 3-month-old male Sprague-Dawley rats and repaired with the implants of calcium phosphate from growth factor enhanced matrix 21 (CaPfromGEM21, control), CaPfromGEM21 preloaded with 10 ng bone morphogenetic protein-2 (BMP-2), CaPfromGEM21 preloaded with 100 ng BMP-2, CaPfromGEM21 preloaded with 0.3 µg platelet-derived growth factor-BB (PDGF-BB), or CaPfromGEM21 preloaded with 3 µg PDGF-BB. The defects were examined 6 weeks after the surgery with X-ray, micro-CT, HE staining and quantitative assessments. X-ray showed defect repair in all the groups. The fracture line became obscure, and the defects were almost fully repaired by the regenerated bone tissues in PDGF-BB group. Micro-CT demonstarted new bone formation in the defects. The new bone volume was significantly greater in PDGF-BB groups than in BMP-2 groups (PBB group than in the control group (PBB has good biocompatibility and can better promote bone regeneration for repairing bone defects.

  17. Retraction: 'Dose-dependent dual effect of HTLV-1 tax oncoprotein on p53-dependent nucleotide excision repair in human T-cells' by Yana Schavinsky-Khrapunsky, Esther Priel and Mordechai Aboud.

    Science.gov (United States)

    2017-06-15

    The above article, published online on 4 October 2007 in Wiley Online Library (wileyonlinelibrary.com), and in Volume 122, pp. 305-316, has been retracted by agreement between the journal Editor in Chief, Professor Peter Lichter, and John Wiley & Sons Ltd. The retraction has been agreed as the bands in Figs 1, 2, 5 and 6 appear to have been manipulated. Schavinsky-Khrapunsky, Y., Priel, E. and Aboud, M. (2008), Dose-dependent dual effect of HTLV-1 tax oncoprotein on p53-dependent nucleotide excision repair in human T-cells. Int. J. Cancer, 122: 305-316. doi:10.1002/ijc.23091. © 2017 UICC.

  18. Triple Negative Breast Cancers Have a Reduced Expression of DNA Repair Genes

    Science.gov (United States)

    Andreis, Daniele; Bertoni, Ramona; Giardini, Roberto; Fox, Stephen B.; Broggini, Massimo; Bottini, Alberto; Zanoni, Vanessa; Bazzola, Letizia; Foroni, Chiara; Generali, Daniele; Damia, Giovanna

    2013-01-01

    DNA repair is a key determinant in the cellular response to therapy and tumor repair status could play an important role in tailoring patient therapy. Our goal was to evaluate the mRNA of 13 genes involved in different DNA repair pathways (base excision, nucleotide excision, homologous recombination, and Fanconi anemia) in paraffin embedded samples of triple negative breast cancer (TNBC) compared to luminal A breast cancer (LABC). Most of the genes involved in nucleotide excision repair and Fanconi Anemia pathways, and CHK1 gene were significantly less expressed in TNBC than in LABC. PARP1 levels were higher in TNBC than in LABC. In univariate analysis high level of FANCA correlated with an increased overall survival and event free survival in TNBC; however multivariate analyses using Cox regression did not confirm FANCA as independent prognostic factor. These data support the evidence that TNBCs compared to LABCs harbour DNA repair defects. PMID:23825533

  19. DNA Repair Deficiency in Neurodegeneration

    Science.gov (United States)

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

    2011-01-01

    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 base lesions is base excision repair, and such repair is crucial for neurons given their high rates of oxygen metabolism. Mismatch repair corrects base mispairs generated during replication and evidence indicates that oxidative DNA damage can cause this pathway to expand trinucleotide repeats, thereby causing Huntington’s disease. Single-strand breaks are common DNA lesions and are associated with the neurodegenerative diseases, ataxia-oculomotor apraxia-1 and spinocerebellar ataxia with axonal neuropathy-1. DNA double-strand breaks are toxic lesions and two main pathways exist for their repair: 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 may be linked with the age-associated neurodegenerative disorders Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis. Mutation in the WRN protein leads to the premature aging disease Werner syndrome, a disorder that features neurodegeneration. In this article we review the evidence linking deficiencies in the DNA repair pathways with neurodegeneration. PMID:21550379

  20. [Repair of skin and soft tissue defects around the knee joints combined with patellar ligament defects using free anterolateral thigh flaps with iliotibial tracts].

    Science.gov (United States)

    Han, Fu; Hu, Dahai; Liu, Yang; Yu, Hongliang; Ma, Shaojun; Wei, Guoxing; Zheng, Zhao

    2015-10-01

    To observe clinical efficacy of using free anterolateral thigh flaps with iliotibial tracts in repairing skin and soft tissue defects around the knee joints with patellar ligament defects. Twelve patients with skin and soft tissue defects around the knee joints and patellar ligament defects were hospitalized from June 2010 to June 2014. The defects of skin and soft tissue ranged from 7 cm × 6 cm to 16 cm × 12 cm in area, and patellar ligament ranged from 5 to 12 cm in length and 2.5 to 4.0 cm in width. Free anterolateral thigh flaps with iliotibial tracts were used to repair these defects. During reconstruction of patellar ligament, both ends of iliotibial tract were successively folded to form tendon-like three-layer structure at first, and then the newly formed structure was wrapped around the broken ends of patellar ligament and fixed with suture. The flap size ranged from 9 cm × 8 cm to 18 cm × 14 cm. The iliotibial tract ranged from 7 to 14 cm in length and 8 to 12 cm in width. The donor sites were closed by grafting with autologous split-thickness skin harvested from thigh or trunk, and parked with gauze. Immediately after operation, the knee joints were fixed in extension with orthosis for 6 weeks. Weight bearing training of affected limbs being kept in extension position was started from 2 weeks after operation, and flexion and extension exercise of affected knee joints was begun from 6 weeks after operation. Before operation and 12 months after operation, the degree of pain around the knee joints and knee joint function were evaluated with the international knee documentation committee knee uation form, and the ranges of flexion and extension of knee joints were also evaluated. The integrity of reconstructed patellar ligament was assessed by color Doppler ultrasound from 6 to 12 months after operation. The occurrence of surgery-related complications was observed in all patients within 12 months after operation. (1) After operation, all flaps survived

  1. Evolution of posterior fossa and brain morphology after in utero repair of open neural tube defects assessed by MRI

    Energy Technology Data Exchange (ETDEWEB)

    Rethmann, Christin; Scheer, Ianina; Kellenberger, Christian Johannes [University Children' s Hospital Zurich, Department of Diagnostic Imaging, Zurich (Switzerland); University of Zurich, The Zurich Center for Fetal Diagnosis and Therapy, Zurich (Switzerland); Children' s Research Center (CRC), Zurich (Switzerland); Meuli, Martin; Mazzone, Luca; Moehrlen, Ueli [University of Zurich, The Zurich Center for Fetal Diagnosis and Therapy, Zurich (Switzerland); Children' s Research Center (CRC), Zurich (Switzerland); University Children' s Hospital Zurich, Department of Pediatric Surgery, Zurich (Switzerland)

    2017-11-15

    To describe characteristics of foetuses undergoing in utero repair of open neural tube defects (ONTD) and assess postoperative evolution of posterior fossa and brain morphology. Analysis of pre- and postoperative foetal as well as neonatal MRI of 27 foetuses who underwent in utero repair of ONTD. Type and level of ONTD, hindbrain configuration, posterior fossa and liquor space dimensions, and detection of associated findings were compared between MRI studies and to age-matched controls. Level of bony spinal defect was defined with exactness of ± one vertebral body. Of surgically confirmed 18 myelomeningoceles (MMC) and 9 myeloschisis (MS), 3 MMC were misdiagnosed as MS due to non-visualisation of a flat membrane on MRI. Hindbrain herniation was more severe in MS than MMC (p < 0.001). After repair, hindbrain herniation resolved in 25/27 cases at 4 weeks and liquor spaces increased. While posterior fossa remained small (p < 0.001), its configuration normalised. Lateral ventricle diameter indexed to cerebral width decreased in 48% and increased in 12% of cases, implying a low rate of progressive obstructive hydrocephalus. Neonatally evident subependymal heterotopias were detected in 33% at preoperative and 50% at postoperative foetal MRI. MRI demonstrates change of Chiari malformation type II (CM-II) features. (orig.)

  2. The use of autologous adult, allogenic juvenile, and combined juvenile-adult cartilage fragments for the repair of chondral defects.

    Science.gov (United States)

    Bonasia, Davide Edoardo; Martin, James A; Marmotti, Antonio; Kurriger, Gail L; Lehman, Abigail D; Rossi, Roberto; Amendola, Annunziato

    2016-12-01

    The goal of the study was to evaluate the repair of chondral lesions treated with combined autologous adult/allogenic juvenile cartilage fragments, compared with isolated adult and isolated juvenile cartilage fragments. Fifty-eight adult (>16 week old) and five juvenile (cartilage fragments; Group 3 = juvenile cartilage fragments; and Group 4 = adult + juvenile cartilage fragments. Killings were performed at 3 and 6 months. The defects were evaluated with ICRS macroscopic score, modified O'Driscoll score, and Collagen type II immunostaining. At 3 months, Group 4 performed better than Group 1, in terms of modified O'Driscoll score (p = 0.001) and Collagen type II immunostaining (p = 0.015). At 6 months, Group 4 showed higher modified O'Driscoll score (p = 0.003) and Collagen type II immunostaining score (p cartilage fragments improved cartilage repair in a rabbit model. In the clinical setting, a new "one-stage" procedure combining the two cartilage sources can be hypothesized, with the advantages of improved chondral repair and large defect coverage, because of the use of an off-the-shelf juvenile allograft. Further studies on larger animals and clinical trials are required to confirm these results.

  3. Repair of segmental bone defect using Totally Vitalized tissue engineered bone graft by a combined perfusion seeding and culture system.

    Directory of Open Access Journals (Sweden)

    Lin Wang

    Full Text Available BACKGROUND: The basic strategy to construct tissue engineered bone graft (TEBG is to combine osteoblastic cells with three dimensional (3D scaffold. Based on this strategy, we proposed the "Totally Vitalized TEBG" (TV-TEBG which was characterized by abundant and homogenously distributed cells with enhanced cell proliferation and differentiation and further investigated its biological performance in repairing segmental bone defect. METHODS: In this study, we constructed the TV-TEBG with the combination of customized flow perfusion seeding/culture system and β-tricalcium phosphate (β-TCP scaffold fabricated by Rapid Prototyping (RP technique. We systemically compared three kinds of TEBG constructed by perfusion seeding and perfusion culture (PSPC method, static seeding and perfusion culture (SSPC method, and static seeding and static culture (SSSC method for their in vitro performance and bone defect healing efficacy with a rabbit model. RESULTS: Our study has demonstrated that TEBG constructed by PSPC method exhibited better biological properties with higher daily D-glucose consumption, increased cell proliferation and differentiation, and better cell distribution, indicating the successful construction of TV-TEBG. After implanted into rabbit radius defects for 12 weeks, PSPC group exerted higher X-ray score close to autograft, much greater mechanical property evidenced by the biomechanical testing and significantly higher new bone formation as shown by histological analysis compared with the other two groups, and eventually obtained favorable healing efficacy of the segmental bone defect that was the closest to autograft transplantation. CONCLUSION: This study demonstrated the feasibility of TV-TEBG construction with combination of perfusion seeding, perfusion culture and RP technique which exerted excellent biological properties. The application of TV-TEBG may become a preferred candidate for segmental bone defect repair in orthopedic and

  4. Functional capacity of XRCC1 protein variants identified in DNA repair-deficient Chinese hamster ovary cell lines and the human population

    DEFF Research Database (Denmark)

    Berquist, Brian R; Singh, Dharmendra Kumar; Fan, Jinshui

    2010-01-01

    XRCC1 operates as a scaffold protein in base excision repair, a pathway that copes with base and sugar damage in DNA. Studies using recombinant XRCC1 proteins revealed that: a C389Y substitution, responsible for the repair defects of the EM-C11 CHO cell line, caused protein instability; a V86R mu...

  5. Osteoblast-seeded bioglass/gelatin nanocomposite: a promising bone substitute in critical-size calvarial defect repair in rat.

    Science.gov (United States)

    Johari, Behrooz; Kadivar, Mehdi; Lak, Shirin; Gholipourmalekabadi, Mazaher; Urbanska, Aleksandra M; Mozafari, Masoud; Ahmadzadehzarajabad, Maryam; Azarnezhad, Asaad; Afshari, Samane; Zargan, Jamil; Kargozar, Saeid

    2016-11-29

    Amid the plethora of methods to repair critical bone defects, there is no one perfect approach. In this study, we sought to evaluate a potent 3-dimensional (3D) bioactive SiO2-CaO-P2O5 glasses (bioglass)/gelatin (gel) scaffold for its biocompatibility by seeding cells as well as for its regenerative properties by animal implantation. Osteoblast cells were seeded onto nanocomposite scaffolds to investigate the process of critical-size calvarial defect via new bone formation. Scanning electron microscopy (SEM) was used to validate topography of the scaffolds, its homogeneity and ideal cellular attachment. Proliferation assay and confocal microscopy were used to evaluate its biocompatibility. To validate osteogenesis of the bioactive nanocomposite scaffolds, they were first implanted into rats and later removed and analyzed at different time points post mortem using histological, immunohistochemical and histomorphometric methods. Based on in vitro results, we showed that our nanocomposite is highly cell-compatible material and allows for osteoblasts to adhere, spread and proliferate. In vivo results indicate that our nanocomposite provides a significant contribution to bone regeneration and is highly biodegradable and biocompatible. So, seeded scaffolds with osteoblasts enhanced repair of critical bone defects via osteogenesis. We demonstrate the feasibility of engineering a nanocomposite scaffold with an architecture resembling the human bone, and provide proof-of-concept validation for our scaffold using a rat animal model.

  6. Lightweight Open-Cell Scaffolds from Sea Urchin Spines with Superior Material Properties for Bone Defect Repair.

    Science.gov (United States)

    Cao, Lei; Li, Xiaokang; Zhou, Xiaoshu; Li, Yong; Vecchio, Kenneth S; Yang, Lina; Cui, Wei; Yang, Rui; Zhu, Yue; Guo, Zheng; Zhang, Xing

    2017-03-22

    Sea urchin spines (Heterocentrotus mammillatus), with a hierarchical open-cell structure similar to that of human trabecular bone and superior mechanical property (compressive strength ∼43.4 MPa) suitable for machining to shape, were explored for potential applications of bone defect repair. Finite element analyses reveal that the compressive stress concentrates along the dense growth rings and dissipates through strut structures of the stereoms, indicating that the exquisite mesostructures play an important role in high strength-to-weight ratios. The fracture strength of magnesium-substituted tricalcium phosphate (β-TCMP) scaffolds produced by hydrothermal conversion of urchin spines is about 9.3 MPa, comparable to that of human trabecular bone. New bone forms along outer surfaces of β-TCMP scaffolds after implantation in rabbit femoral defects for one month and grows into the majority of the inner open-cell spaces postoperation in three months, showing tight interface between the scaffold and regenerative bone tissue. Fusion of beagle lumbar facet joints using a Ti-6Al-4V cage and β-TCMP scaffold can be completed within seven months with obvious biodegradation of the β-TCMP scaffold, which is nearly completely degraded and replaced by newly formed bone ten months after implantation. Thus, sea urchin spines suitable for machining to shape have advantages for production of biodegradable artificial grafts for bone defect repair.

  7. Acquired Left Atrial-to-Right Ventricular Shunt with Mitral Valve Incompetence: A Rare Sequela after Repair of Atrioventricular Septal Defect

    OpenAIRE

    Mohapatra, Srikant; Minhas, Harpreet Singh; Virmani, Sanjula; Mishra, Bana Bihari; Mukherjee, Kaushik; Banerjee, Amit

    2009-01-01

    Acquired left ventricular-to-right atrial communication is encountered periodically. This condition is chiefly attributable to surgical mishaps, trauma, endocarditis, or endomyocardial biopsy. In a few instances, a Gerbode-like defect develops after the repair of an atrioventricular septal defect. Our search of the worldwide medical literature revealed just 1 report of a “mirror” occurrence of a Gerbode-like defect: a shunt between the left atrium and the right ventricle.

  8. Junctional ectopic tachycardia following repair of congenital heart defects-experience in multimodal management from a West African Centre.

    Science.gov (United States)

    Entsua-Mensah, Kow; Aniteye, Ernest; Sereboe, Lawrence Agyemang; Tettey, Mark Mawutor; Edwin, Frank; Tamatey, Martin; Delia, Ibrahim; Gyan, Kofi Bafoe

    2012-01-01

    Postoperative junctional ectopic tachycardia (JET) is a rare and transient phenomenon occurring after repair of congenital heart defects. Report on this arrhythmia in the subregion is rare. We set out to determine the incidence of this arrhythmia and review the treatment and outcomes of treatment in our centre. Retrospective search of the records of all patients aged 18 years and below admitted into the intensive care unit (ICU) following repair or palliation of a congenital heart defect over 5 years, from January 1, 2006 to December 31, 2010. A review of clinical notes, operative records, anaesthetic charts, cardiopulmonary bypass (CPB) records, nursing observation charts, electrocardiograms (ECGs) and out-patient follow-up records was undertaken. 510 children under 18 years were enlisted. 7 cases of postoperative JET were recorded, (1.37%). 184 (36.1%) of these were performed under CPB. All JET cases were from cases done under CPB, 3.8%. Median age was 3 years and median weight 11.3 kg. No patient was febrile at diagnosis. 4 patients had amiodarone administration, 5 had magnesium sulphate infusion, 2 patients had direct current shock (DCS) whilst 3 patients had all three therapeutic modalities. All patients had control of the arrhythmia with conversion to sinus rhythm and no recurrence. We report a JET incidence of 1.37% among children undergoing CPB for repair of congenital heart defects. We demonstrate the therapeutic effectiveness of amiodarone, magnesium sulphate infusions and DCS alone or in combination in the management of JET on various substrates with good outcome.

  9. Excision repair cross-complementation group 1 (ERCC1) in platinum-based treatment of non-small cell lung cancer with special emphasis on carboplatin: a review of current literature

    DEFF Research Database (Denmark)

    Vilmar, A.; Sorensen, J.B.

    2009-01-01

    BACKGROUND: Patients diagnosed with advanced non-small cell lung cancer have a dismal prognosis and are often relative resistant to chemotherapy. A need for markers has emerged based on tumour biology in order to predict which patients will respond to treatment. Excision repair cross-complementat......BACKGROUND: Patients diagnosed with advanced non-small cell lung cancer have a dismal prognosis and are often relative resistant to chemotherapy. A need for markers has emerged based on tumour biology in order to predict which patients will respond to treatment. Excision repair cross......-complementation group 1 (ERCC1) has shown potential as a predictive marker in patients with NSCLC treated with cisplatin-based chemotherapy. Carboplatin has gained widespread use in the treatment of advanced NSCLC and its mechanisms of action are likely similar to that of cisplatin. MATERIALS AND METHODS: A literature...... articles and 1 clinical abstract were identified. Laboratory methods were mainly RT-PCR (reverse transcriptase polymerase chain reaction) or immunohistochemistry (IHC) for expression of ERCC1. Preclinical studies pointed towards similar mechanisms of chemotherapy-resistance among platinum compounds...

  10. In situ repair of bone and cartilage defects using 3D scanning and 3D printing

    OpenAIRE

    Li, Lan; Yu, Fei; Shi, Jianping; Shen, Sheng; Teng, Huajian; Yang, Jiquan; Wang, Xingsong; Jiang, Qing

    2017-01-01

    Three-dimensional (3D) printing is a rapidly emerging technology that promises to transform tissue engineering into a commercially successful biomedical industry. However, the use of robotic bioprinters alone is not sufficient for disease treatment. This study aimed to report the combined application of 3D scanning and 3D printing for treating bone and cartilage defects. Three different kinds of defect models were created to mimic three orthopedic diseases: large segmental defects of long bon...

  11. PLGA/TCP composite scaffold incorporating bioactive phytomolecule icaritin for enhancement of bone defect repair in rabbits.

    Science.gov (United States)

    Chen, S-H; Lei, M; Xie, X-H; Zheng, L-Z; Yao, D; Wang, X-L; Li, W; Zhao, Z; Kong, A; Xiao, D-M; Wang, D-P; Pan, X-H; Wang, Y-X; Qin, L

    2013-05-01

    Bone defect repair is challenging in orthopaedic clinics. For treatment of large bone defects, bone grafting remains the method of choice for the majority of surgeons, as it fills spaces and provides support to enhance biological bone repair. As therapeutic agents are desirable for enhancing bone healing, this study was designed to develop such a bioactive composite scaffold (PLGA/TCP/ICT) made of polylactide-co-glycolide (PLGA) and tricalcium phosphate (TCP) as a basic carrier, incorporating a phytomolecule icaritin (ICT), i.e., a novel osteogenic exogenous growth factor. PLGA/TCP/ICT scaffolds were fabricated as PLGA/TCP (control group) and PLGA/TCP in tandem with low/mid/high-dose ICT (LICT/MICT/HICT groups, respectively). To evaluate the in vivo osteogenic and angiogenic potentials of these bioactive scaffolds with slow release of osteogenic ICT, the authors established a 12 mm ulnar bone defect model in rabbits. X-ray and high-resolution peripheral quantitative computed tomography results at weeks 2, 4 and 8 post-surgery showed more newly formed bone within bone defects implanted with PLGA/TCP/ICT scaffolds, especially PLGA/TCP/MICT scaffold. Histological results at weeks 4 and 8 also demonstrated more newly mineralized bone in PLGA/TCP/ICT groups, especially in the PLGA/TCP/MICT group, with correspondingly more new vessel ingrowth. These findings may form a good foundation for potential clinical validation of this innovative bioactive scaffold incorporated with the proper amount of osteopromotive phytomolecule ICT as a ready product for clinical applications. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Factors associated with moderate or severe left atrioventricular valve regurgitation within 30 days of repair of incomplete atrioventricular septal defect

    Directory of Open Access Journals (Sweden)

    Marcelo Felipe Kozak

    2015-04-01

    Full Text Available AbstractIntroduction:Left atrioventricular valve regurgitation is the most concerning residual lesion after surgical correction of atrioventricular septal defect.Objective:To determine factors associated with moderate or greater left atrioventricular valve regurgitation within 30 days of surgical repair of incomplete atrioventricular septal defect.Methods:We assessed the results of 51 consecutive patients 14 years-old and younger presenting with incomplete atrioventricular septal defect that were operated on at our practice between 2002 and 2010. The following variables were considered: age, weight, absence of Down syndrome, grade of preoperative left atrioventricular valve regurgitation, abnormalities on the left atrioventricular valve and the use of annuloplasty. The median age was 4.1 years; the median weight was 13.4 Kg; 37.2% had Down syndrome. At the time of preoperative evaluation, there were 23 cases with moderate or greater left atrioventricular valve regurgitation (45.1%. Abnormalities on the left atrioventricular valve were found in 17.6%; annuloplasty was performed in 21.6%.Results:At the time of postoperative evaluation, there were 12 cases with moderate or greater left atrioventricular valve regurgitation (23.5%. The variation between pre- and postoperative grades of left atrioventricular valve regurgitation of patients with atrioventricular valve malformation did not reach significance (P=0.26, unlike patients without such abnormalities (P=0.016. During univariate analysis, only absence of Down syndrome was statistically significant (P=0.02. However, after a multivariate analysis, none of the factors reached significance.Conclusion:None of the factors studied was determinant of a moderate or greater left atrioventricular valve regurgitation within the first 30 days of repair of incomplete atrioventricular septal defect in the sample. Patients without abnormalities on the left atrioventricular valve benefit more of the operation.

  13. Harvey Cushing's repair of a dural defect after a traumatic brain injury: novel use of a fat graft.

    Science.gov (United States)

    Zaidi, Hasan A; Pendleton, Courtney; Cohen-Gadol, Aaron A; Quinones-Hinojosa, Alfredo

    2011-01-01

    A review of Harvey Cushing's surgical cases at Johns Hopkins Hospital revealed new information about his early work with the use of fat grafts to close dural defects. The Johns Hopkins Hospital surgical records from 1896 to 1912 were reviewed. A single case in which Cushing used an autologous fat graft to repair a dural defect in 1912 after a traumatic brain injury was selected for further study. An 18-year-old white female patient presented with recurring seizures in her sleep approximately 12 years after a traumatic brain injury. A depressed skull fracture as a result of this injury was explored by Cushing, and a dural defect was found. Fat was harvested from the thigh of the patient and was sutured in layers to cover the defect. Cushing noted that this was the first of its kind of operation and "probably of very little use." The patient was discharged within 2 weeks after the operation despite recurrence of her seizure episodes. Despite its questionable functional success, we report herein a previously unpublished operative case by Harvey Cushing's in which an autologous fat graft was used to close a traumatic wound resulting in a dural defect. This report predates currently known published reports of the use of fat to seal dural defects. Cushing recognized that a factor found in fat tissue may aid in wound healing. Contemporary studies indicate the presence of mesenchymal stem cells in fat tissue may be responsible for the accelerated healing and reduced incidence of cerebral spinal fluid leaks after cranial surgery. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Hypospadias repair

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003000.htm Hypospadias repair To use the sharing features on this page, please enable JavaScript. Hypospadias repair is surgery to correct a defect in ...

  15. Defective DSB repair correlates with abnormal nuclear morphology and is improved with FTI treatment in Hutchinson-Gilford progeria syndrome fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Constantinescu, Dan [Department of Cell Biology-Physiology, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Pittsburgh Development Center, Magee-Women' s Research Institute, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Csoka, Antonei B. [Division of Geriatrics, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA 15260 (United States); Navara, Christopher S. [Division of Developmental and Regenerative Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Pittsburgh Development Center, Magee-Women' s Research Institute, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Schatten, Gerald P., E-mail: schattengp@upmc.edu [Division of Developmental and Regenerative Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Cell Biology-Physiology, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Pittsburgh Development Center, Magee-Women' s Research Institute, University of Pittsburgh, Pittsburgh, PA 15260 (United States)

    2010-10-15

    Impaired DSB repair has been implicated as a molecular mechanism contributing to the accelerating aging phenotype in Hutchinson-Gilford progeria syndrome (HGPS), but neither the extent nor the cause of the repair deficiency has been fully elucidated. Here we perform a quantitative analysis of the steady-state number of DSBs and the repair kinetics of ionizing radiation (IR)-induced DSBs in HGPS cells. We report an elevated steady-state number of DSBs and impaired repair of IR-induced DSBs, both of which correlated strongly with abnormal nuclear morphology. We recreated the HGPS cellular phenotype in human coronary artery endothelial cells for the first time by lentiviral transduction of GFP-progerin, which also resulted in impaired repair of IR-induced DSBs, and which correlated with abnormal nuclear morphology. Farnesyl transferase inhibitor (FTI) treatment improved the repair of IR-induced DSBs, but only in HGPS cells whose nuclear morphology was also normalized. Interestingly, FTI treatment did not result in a statistically significant reduction in the higher steady-state number of DSBs. We also report a delay in localization of phospho-NBS1 and MRE11, MRN complex repair factors necessary for homologous recombination (HR) repair, to DSBs in HGPS cells. Our results demonstrate a correlation between nuclear structural abnormalities and the DSB repair defect, suggesting a mechanistic link that may involve delayed repair factor localization to DNA damage. Further, our results show that similar to other HGPS phenotypes, FTI treatment has a beneficial effect on DSB repair.

  16. An inside-out vein graft filled with platelet-rich plasma for repair of a short sciatic nerve defect in rats.

    Science.gov (United States)

    Kim, Ji Yeong; Jeon, Woo Joo; Kim, Dong Hwee; Rhyu, Im Joo; Kim, Young Hwan; Youn, Inchan; Park, Jong Woong

    2014-07-15

    Platelet-rich plasma containing various growth factors can promote nerve regeneration. An inside-out vein graft can substitute nerve autograft to repair short nerve defects. It is hypothesized that an inside-out vein graft filled with platelet-rich plasma shows better effects in the repair of short sciatic nerve defects. In this study, an inside-out vein autograft filled with platelet-rich plasma was used to bridge a 10 mm-long sciatic nerve defect in rats. The sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better improved than that of rats with a simple inside-out vein autograft. At 6 and 8 weeks, the sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better than that of rats undergoing nerve autografting. Compared with the sciatic nerve repaired with a simple inside-out vein autograft, the number of myelinated axons was higher, axon diameter and myelin sheath were greater in the sciatic nerve repaired with an inside-out vein autograft filled with platelet-rich plasma and they were similar to those in the sciatic nerve repaired with nerve autograft. These findings suggest that an inside-out vein graft filled with platelet-rich plasma can substitute nerve autograft to repair short sciatic nerve defects.

  17. Genomic Approaches to DNA repair and Mutagenesis

    OpenAIRE

    Wyrick, John J.; Roberts, Steven A.

    2015-01-01

    DNA damage is a constant threat to cells, causing cytotoxicity as well as inducing genetic alterations. The steady-state abundance of DNA lesions in a cell is minimized by a variety of DNA repair mechanisms, including DNA strand break repair, mismatch repair, nucleotide excision repair, base excision repair, and ribonucleotide excision repair. The efficiencies and mechanisms by which these pathways remove damage from chromosomes have been primarily characterized by investigating the processin...

  18. Nucleotide Excision Repair Lesion-Recognition Protein Rad4 Captures a Pre-Flipped Partner Base in a Benzo[a]pyrene-Derived DNA Lesion: How Structure Impacts the Binding Pathway.

    Science.gov (United States)

    Mu, Hong; Geacintov, Nicholas E; Min, Jung-Hyun; Zhang, Yingkai; Broyde, Suse

    2017-06-19

    The xeroderma pigmentosum C protein complex (XPC) recognizes a variety of environmentally induced DNA lesions and is the key in initiating their repair by the nucleotide excision repair (NER) pathway. When bound to a lesion, XPC flips two nucleotide pairs that include the lesion out of the DNA duplex, yielding a productively bound complex that can lead to successful lesion excision. Interestingly, the efficiencies of NER vary greatly among different lesions, influencing their toxicity and mutagenicity in cells. Though differences in XPC binding may influence NER efficiency, it is not understood whether XPC utilizes different mechanisms to achieve productive binding with different lesions. Here, we investigated the well-repaired 10R-(+)-cis-anti-benzo[a]pyrene-N 2 -dG (cis-B[a]P-dG) DNA adduct in a duplex containing normal partner C opposite the lesion. This adduct is derived from the environmental pro-carcinogen benzo[a]pyrene and is likely to be encountered by NER in the cell. We have extensively investigated its binding to the yeast XPC orthologue, Rad4, using umbrella sampling with restrained molecular dynamics simulations and free energy calculations. The NMR solution structure of this lesion in duplex DNA has shown that the dC complementary to the adducted dG is flipped out of the DNA duplex in the absence of XPC. However, it is not known whether the "pre-flipped" base would play a role in its recognition by XPC. Our results show that Rad4 first captures the displaced dC, which is followed by a tightly coupled lesion-extruding pathway for productive binding. This binding path differs significantly from the one deduced for the small cis-syn cyclobutane pyrimidine dimer lesion opposite mismatched thymines [ Mu , H. , ( 2015 ) Biochemistry , 54 ( 34 ), 5263 - 7 ]. The possibility of multiple paths that lead to productive binding to XPC is consistent with the versatile lesion recognition by XPC that is required for successful NER.

  19. Yeast DNA-repair gene RAD14 encodes a zinc metalloprotein with affinity for ultraviolet-damaged DNA.

    OpenAIRE

    Guzder, S N; Sung, P; Prakash, L; Prakash, S

    1993-01-01

    Xeroderma pigmentosum (XP) patients suffer from a high incidence of skin cancers due to a defect in excision repair of UV light-damaged DNA. Of the seven XP complementation groups, A-G, group A represents a severe and frequent form of the disease. The Saccharomyces cerevisiae RAD14 gene is a homolog of the XP-A correcting (XPAC) gene. Like XP-A cells, rad14-null mutants are defective in the incision step of excision repair of UV-damaged DNA. We have purified RAD14 protein to homogeneity from ...

  20. Repair of defective composite restorations. A questionnaire study among dentists in the Public Dental Service in Norway.

    Science.gov (United States)

    Staxrud, F; Tveit, A B; Rukke, H V; Kopperud, S E

    2016-09-01

    This study aimed to investigate dentists' treatment choices concerning "repair or replacement" of defective restorations. A pre-coded questionnaire was sent electronically to all dentists (n=1313) in the Public Dental Service (PDS) in Norway. Part one: The dentists were asked about age and gender, whether they performed direct restorative therapy/amount of time spent on fillings made per day due to: Primary caries, Repair of restorations or Replacement of restoration/what kind of bonding agents used and pre-treatment of the residual restoration. Part two: The dentists were asked to consider the best treatment for three patient cases with tooth/restoration fractures. Response rate was 55.8%, (69.6% females, 30.4% males). Respondent age varied from 25 to 77 years (mean 41.8, SD 12.4). Part one: The dentists spent on average 57.5% of the working day placing restorations, making from 1 to 30 (mean 7.7, SD 3.6) restorations per day. Reasons for treatment were; Primary caries 55.7% (SD 19.1%), repair of restorations 26.7% (SD 14.8%), replacement of fillings 18.2% (SD 11.2%). Two-step etch and rinse (ER), 3-step ER and Self-etch (SE) were used by 48.7%, 24.6% and 26.7% of the respondents, respectively. A silanising agent was used by 7.4%. Part two: Treatment choices: Repair with RC: 89.6% in case one, 86.9% in case two and 54.1% in case three. Young dentists suggested invasive treatment more often than old dentists (>38 years). Operative dentistry claims 57.5% of PDS dentists' working day. In addition to primary caries, repair and replacement of restorations accounted for 27% and 18% of the reasons for placing restorations. The idea of "minimal intervention dentistry" seems to have great influence among dentists in PDS (Norway), as they seek to preserve dental hard tissue as much as possible by choosing repair before replacement. No gender differences were observed, but older dentists seem to favour repair compared with the younger dentists. Copyright © 2016 Elsevier Ltd

  1. Enhanced Critical Size Defect Repair in Rabbit Mandible by Electrospun Gelatin/β-TCP Composite Nanofibrous Membranes

    Directory of Open Access Journals (Sweden)

    Mingming Xu

    2015-01-01

    Full Text Available The design and fabrication of biodegradable barrier membranes with satisfactory structure and composition remain a considerable challenge for periodontal tissue regeneration. We have developed a biomimetic nanofibrous membrane made from a composite of gelatin and β-tricalcium phosphate (β-TCP. We previously confirmed the in vitro biological performance of the membrane material, but the efficacy of the membranes in promoting bone repair in situ has not yet been examined. Gelatin/β-TCP composite nanofibers were fabricated by incorporation of 20 wt.% β-TCP nanoparticles into electrospun gelatin nanofibers. Electron microscopy showed that the composite membranes presented a nonwoven structure with an interconnected porous network and had a rough surface due to the β-TCP nanoparticles, which were distributed widely and uniformly throughout the gelatin-fiber matrix. The repair efficacy of rabbit mandible defects implanted with bone substitute