Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 3 uppsatser.

by Au Lai Yin, Cathy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 50-66). / Chapter I. --- ABSTRACT --- p.i / Chapter II. --- ACKNOWLEDGMENTS --- p.iii / Chapter III. --- TABLE OF CONTENTS --- p.iv / Chapter IV. --- LIST OF TABLES --- p.viii / Chapter V. --- LIST OF FIGURES --- p.x / Chapter VI. --- INTRODUCTION --- p.1 / Chapter VII. --- LITERATURE REVIEW --- p.3 / Chapter A. --- Mycobacterial tuberculosis Infections --- p.3 / Chapter B. --- Diagnostic Criteria forM .tuberculosis Infections --- p.3 / Chapter C. --- Mycobacteriological Laboratory Investigations for M. tuberculosis --- p.4 / Chapter 1. --- Conventional methods --- p.4 / Chapter 2. --- Rapid methods --- p.4 / Chapter D. --- Polymerase chain reaction (PCR) - the Principle --- p.5 / Chapter E. --- Application of PCR for Detection of M. tuberculosis --- p.6 / Chapter 1. --- Choice of target sequences --- p.6 / Chapter 2. --- Choice of method for the detection & identification of PCR-amplified product --- p.7 / Chapter 3. --- Studies on pure cultures --- p.9 / Chapter a. --- Detection limit - target DNA --- p.9 / Chapter b. --- Detection limit - Colony forming units --- p.9 / Chapter c. --- Detection limit - Number of cells --- p.10 / Chapter 4. --- Studies on clinical specimens --- p.10 / Chapter 5. --- Problems --- p.12 / Chapter a. --- Availability of target DNA --- p.13 / Chapter (i) --- Cell breakage efficiency --- p.13 / Chapter (ii) --- Target sequence --- p.14 / Chapter b. --- Inhibitory factors for Taq polymerase --- p.14 / Chapter c. --- Contamination --- p.15 / Chapter VIII. --- MATERIALS AND METHODS --- p.16 / Chapter A. --- Bacterial Strains and Strain Maintenance --- p.16 / Chapter 1. --- Reference Strains --- p.16 / Chapter 2. --- Clinical isolates --- p.16 / Chapter B. --- Growth media and culture conditions --- p.17 / Chapter C. --- Restriction Fragment Length Polymorphism (RFLP) --- p.17 / Chapter 1. --- Extraction of chromosomal DNA from M. tuberculosis --- p.18 / Chapter 2. --- Digestion of chromosomal DNA by PVU II --- p.19 / Chapter 3. --- Separation of digested DNA fragment by electrophoresis --- p.19 / Chapter 4. --- Southern Blotting --- p.19 / Chapter 5. --- Preparation of DNA probes by Polymerase Chain Reaction --- p.20 / Chapter 6. --- Hybridization --- p.21 / Chapter 7. --- Detection --- p.21 / Chapter D. --- Assessment of number of organisms --- p.22 / Chapter 1. --- Viable cell count --- p.22 / Chapter 2. --- Direct cell count --- p.22 / Chapter E. --- Assessment of the presence of IS6110/986 in M. tuberculosis isolates --- p.23 / Chapter F. --- Human leukaemic monocytic cell line (THP-1) --- p.23 / Chapter 1. --- Growth media and maintenance --- p.23 / Chapter 2. --- Culture Conditions --- p.24 / Chapter 3. --- Uptake of M. tuberculosis --- p.24 / Chapter G. --- Cell breakage and DNA extraction methodologies --- p.25 / Chapter H. --- Polymerase chain reaction (PCR) methodologies --- p.28 / Chapter 1. --- Primer and probe --- p.28 / Chapter 2. --- PCR conditions --- p.28 / Chapter 3. --- Detection --- p.29 / Chapter I. --- Patients and Clinical specimens --- p.30 / Chapter 1. --- Patients recruitment --- p.30 / Chapter 2. --- Clinical specimens --- p.30 / Chapter IX. --- RESULTS --- p.32 / Chapter A. --- "Development or Selection of a ""Standardized"" PCR Protocol for the Detection of M. tuberculosis Using Pure Cultures In Vitro" --- p.32 / Chapter 1. --- Selection of organisms for verification of the PCR protocol --- p.32 / Chapter 2. --- Optimization of the PCR conditions --- p.32 / Chapter 3. --- Detection limit of target DNA using the PCR procedure --- p.33 / Chapter B. --- Initial Screening of Six Different Cell Breakage Procedures Using Pure Cultures of M. tuberculosis Isolates TB19 &22a Based on Detection Limits of Colony Forming Units and Number of Cells --- p.34 / Chapter C. --- Comparison of Method 1 and Method 2 Based on Detection Limits of Colony Forming Units and Number of Cells Using Pure Cultures of the Eight Clinical Isolates of M. tuberculosis with variable copies of IS6110/986 --- p.34 / Chapter D. --- Detection of M. tuberculosis Isolates Within Macrophages --- p.35 / Chapter 1. --- Uptake of M. tuberculosis cells by THP-1 --- p.35 / Chapter 2. --- Comparison of the Six Different Cell Breakage Procedures Using Pure Cultures of M. tuberculosis Isolates TB19 & 22a Phagocytized by Activated THP-1 Macrophages --- p.35 / Chapter 3. --- Comparison of Method 1 and Method 2 Using Pure Cultures of the Eight Clinical Isolates of M. tuberculosis Phagocytized by Activated THP-1 Macrophages --- p.36 / Chapter E. --- Analysis of Clinical Specimens Using Method 1 & 2 with the Optimized PCR Protocol --- p.36 / Chapter 1. --- Bronchial Aspirate & Bronchoaveolar Lavage Fluid --- p.36 / Chapter 2. --- Pleural Fluid --- p.37 / Chapter 3. --- Tissue --- p.37 / Chapter 4. --- Sputum --- p.38 / Chapter 5. --- Cerebrospinal Fluid --- p.38 / Chapter X. --- DISCUSSION --- p.39 / Chapter A. --- Selection of IS6110/986 for DNA amplification --- p.39 / Chapter B. --- Optimization of PCR conditions reflected by detection limit of target DNA --- p.40 / Chapter C. --- Selection of cell breakage methods based on detection limits of CFU and/or number of mycobacterial cells --- p.41 / Chapter D. --- Application of Methods 1 & 2 and the optimized PCR protocol for clinical specimens --- p.43 / Chapter 1. --- Bronchial aspirates and bronchoaveolar lavage fluids --- p.43 / Chapter 2. --- Pleural fluids --- p.44 / Chapter 3. --- Tissues --- p.45 / Chapter 4. --- Sputa --- p.46 / Chapter 5. --- Cerebrospinal fluids --- p.46 / Chapter XI. --- CONCLUSION --- p.48 / Chapter XII. --- LITERATURE CITED --- p.50 / Chapter XIII --- TABLES --- p.67 / Chapter XIV. --- FIGURES --- p.85

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 107-114).

Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Bibliography: p. 117-123.

This thesis is divided into three parts, united by the theme of the development of selective inhibitors of mammalian cell DNA polymerase delta (pol δ). The first part consists of an investigation of the cytotoxic mechanism(s) of certain 2-substituted adenine analogs, selected on the basis of their inhibitory properties towards DNA polymerase alpha (pol α) and mammalian cell DNA synthesis. The second is a direct search for inhibitors of isolated pol δ, and an investigation of inhibitory mechanisms. The third consists of measurement of the effects of a selective pol δ inhibitor on cellular DNA synthesis. Mechanism of Cytotoxicity of 2-substituted adenine analoqs. The mechanism of inhibition by 2-(p-n-butylanilino)-2'-deoxyadenosine (BuAdA), and related compounds, of Chinese hamster ovary (CHO) cell ([3H]thymidine [3H]TdR) incorporation, was investigated. The potency of the compound could largely be explained by its potency (IC50 = 23 μM) as an inhibitor of CHO cell [3H]TdR uptake. BuAdA inhibited incorporation by CHO cells of [32p]phosphate into DNA relatively weakly, displaying an IC50value of 80 μM. Differential inhibition of DNA polymerases alpha and delta. Known DNA polymerase inhibitors of a structurally wide range were screened for their ability to inhibit pol δ derived from calf thymus selectively with respect to pol α derived from the same tissue. Pyrophosphate (PPi) and difluoromethanediphosphonate each inhibited pol δ weakly, but with greater potency than pol α. Based on this lead, an expanded series of PPi analogs was screened. Carbonyldiphosphonate (COMDP) inhibited pol δ with a potency (Ki = 1.8 μM) twenty-two times greater than that displayed for pol α. Kinetic studies indicated that COMDP inhibited pol δ competitively with the dNTP specified by the template, but not competitively with the template:primer. Analogous experiments with pol α showed that the compound inhibited that enzyme uncompetitively with the dNTP, and not competitively with the template:primer. COMDP was a weak inhibitor of the 3' → 5' exonuclease activity of pol δ, displaying an IC50value greater than 1 mM. Inhibition of permeabilized cell DNA synthesis bv a selective pol δ inhibitor. The potency of COMDP as an inhibitor of permeabilized CHO cell DNA synthesis (IC50= 200 μM) did not clearly indicate the participation of pol δ in cellular DNA replication. Prospectus. The thesis concludes with a prospectus for the development of pol δ inhibitors with improved properties compared to COMDP.

Abstract DNA replication is a process in which a cell duplicates its genome before cell division, and must proceed accurately and in organized manner to guarantee maintenance of the integrity of the genetic information. DNA polymerases are enzymes that catalyse the synthesis of the new DNA strand by utilizing the parental strand as a template. In addition to chromosomal replication, DNA synthesis and therefore DNA polymerases are also needed in other processes like DNA repair and DNA recombination. The DNA polymerase is an essential DNA polymerase in eukaryotes and is required for chromosomal DNA replication. It has also been implicated in DNA repair, recombination, and in transcriptional and cell cycle control. The regulation of the human enzyme was explored by analysing its expression, phosphorylation and protein-protein interactions. Expression of both the A and B subunits of the human DNA polymerase ε was strongly growth-regulated. After serum-stimulation of quiescent fibroblasts, the steady-state mRNA levels were up-regulated at least 5-fold. In actively cycling cells, however, the steady-state mRNA and protein levels fluctuated less than 2-fold, being highest in G1/S phase. The promoter of the B subunit gene was analysed in detail. The 75 bp core promoter was essentially dependent on the Sp1 transcription factor. Furthermore, mitogenic control of the promoter required an intact E2F binding element, and binding of E2F2, E2F4 and p107 was demonstrated in vitro. A down-regulation element, located immediately downstream from the core promoter, bound E2F1, NF-1 and pRb transcription factors. A model of the promoter function is presented. Topoisomerase IIβ binding protein 1 (TopBP1) was found to be associated with human DNA polymerase ε. TopBP1 contains eight BRCT domains and is homologous to Saccharomyces cerevisiae Dpb11, Schizosaccharomyces pombe Cut5, Drosophila melanogaster Mus101 and the human Breast Cancer susceptibility protein 1 (BRCA1). TopBP1 is a phosphoprotein, whose expression is induced at the G1/S border and is required for chromosomal DNA replication. It co-localizes in S phase with BRCA1 into discrete foci, which do not represent sites of ongoing DNA replication. However, if DNA is damaged or replication is blocked in S phase cells, TopBP1 and BRCA1 re-localize into proliferating cell nuclear antigen (PCNA) containing foci that represent stalled replication forks. Finally, phosphorylation of DNA polymerase ε was described and at least three immunologically distinct and differentially phosphorylated forms were shown to exist. Phosphorylation is on serine and threonine residues and shows a cell cycle dependent fluctuation, but is not affected by DNA damage or by inhibition of DNA replication. BRCA1 co-immunoprecipitates with a hypophosphorylated form of DNA polymerase ε. In contrast, TopBP1 was shown to be associated with a hyperphosphorylated form.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2010.

Thesis (Ph.D. in Molecular Biology) -- University of Colorado at Denver and Health Sciences Center, 2005. / Typescript. Includes bibliographical references (leaves 124-136).

A via de Reparo por Excisão de Nucleotídeos (NER) é responsável pelo reparo das lesões causadas pela luz ultravioleta (UV) e de outras lesões capazes de distorcer a dupla hélice, bloqueando a replicação e a transcrição. Os pacientes que apresentam as síndromes recessivas raras Xeroderma Pigmentosum (XP), tricotiodistrofia (TTD) e síndrome de Cockayne (CS) possuem mutações em algum dos 11 genes relacionados ao NER e à transcrição basal. Mutações na proteína XPD levam ao surgimento de diferentes fenótipos: XP, TTD, XP/CS ou COFS (Cerebro-Oculo-Facio-Skeletal Syndrome), uma forma rara de CS. Os pacientes XP apresentam alta incidência de câncer de pele, o que não ocorre com os pacientes TTD e CS, além de poderem apresentar perda neuronal progressiva, enquanto todos os CS e TTD apresentam uma diminuição na mielinização do cérebro. As neuropatologias são provavelmente associadas a problemas no reparo de danos endógenos no DNA das células nervosas. Diversos trabalhos mostraram o envolvimento do NER no reparo desses danos, os quais pensava-se serem reparados apenas por outro mecanismo, o Reparo por Excisão de Base. Neste trabalho mostramos que fibroblastos de pacientes XP-D, XP-D/CS e TTD, portadores de mutações em XPD, são sensíveis ao estresse oxidativo induzido pelo tratamento com azul de metileno fotoativado, apresentando bloqueio prolongado no ciclo celular e permanência da sinalização de danos ao DNA. A complementação das diferentes linhagens com o gene XPD/ERCC2 foi capaz de restaurar a sobrevivência celular. Foram detectadas diferenças importantes na capacidade de reparo/retomada da transcrição após danos gerados por estresse oxidativo em DNA plasmidial, além da ativação de vias diferentes de morte celular: fibroblastos XP-D apresentam maior capacidade de reparo e apresentam morte por apoptose após estresse oxidativo, enquanto os fibroblastos XP-D/CS e TTD apresentam menor capacidade de reparo ativação de mais de uma via de morte celular (apoptose e necrose), diferenças que podem estar ligadas ao fenótipo dos pacientes. Mutações no gene codificante para a DNA polimerase n, POLH, estão associadas à forma variante de XP (XP-V). Pol n é uma polimerase especializada na síntese translesão (TLS) de fotoprodutos, além de estar implicada na TLS de outros tipos de lesões como bases oxidadas, e em vias não relacionadas à TLS como a hipermutação somática e à replicação de regiões de DNA com arquiteturas não-canônicas. Neste trabalho mostramos que os fibroblastos de pacientes XP-V apresentam sensibilidade ao estresse oxidativo. Mostramos uma indução da proteína pol n em fibroblastos primários após danos genotóxicos, associada ao aumento da capacidade de lidar com a parada na forquilha de replicação, possibilitando a continuidade da replicação do DNA e ao aumento da sobrevivência celular. Mostramos uma diferença na estabilidade genômica nos genes das imunoglobulinas dos pacientes XP-V idosos em comparação com os pacientes jovens e controles de idade pareada, mostrando que a ausência dessa polimerase pode estar ligada ao aumento da instabilidade genômica nesses genes / The Nucleotide Excision Repair (NER) pathway is responsible for the repair of UV photoproducts and other bulky lesions that block both replication and transcription. Patients with the rare recessive disorders Xeroderma Pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne Syndrome (CS) carry mutations in one of the 11 NER genes, linked to repair and basal transcription. Mutations in XPD lead to different phenotypes: XP, TTD, XP/CS or COFS (Cerebro-Oculo-Facio-Skeletal Syndrome), a rare form of CS. XP patients have high incidence of skin cancer, which does not occur in TTD or CS patients, although ther may present neurodegeneration, while all CS and TTD patients have neurodevelopmental symptoms linked to dysmielynation. The pathology of these neurological diseases is probably associated with deficient repair of DNA lesions in nervous cells, generated by endogenous processes. Many groups including ours have demonstrated the involvement of NER in the repair of these lesions, previously thought to be exclusively repaired by Base Excision Repair. In this work we show high sensitivity of both primary and transformed XP-D, XP-D/CS and TTD human fibroblasts in response to oxidative stress generated by photoactivated methylene blue, with prolonged cell cycle arrest and DNA damage signaling. The complementation of the three different cell lines with the XPD/ERCC2 gene was able to restore cell survival. We detected important differences in repair capacity/transcription resumption after damage generated by oxidative stress in plasmid DNA, besides the activation of different cell death pathways: XP-D cells have higher repair capacity and die by apoptosis, while XP-D/CS and TTD cells have little repair capacity and activate more than one death pathway (apoptosis and necrosis). We believe these differences can be related to the patients\' phenotypes. Mutations in DNA polymerase n coding gene, POLH, are associated with the variant form of XP (XP-V). Pol n is a translesion synthesis (TLS) polymerase specialized in the TLS past CPD photoproducts, besides other lesions like oxidized bases, and in other processes like somatic hypermutation and DNA replication in structured regions. In this work we show XP-V human fibroblasts are sensitive to oxidative stress. We detected an induction of pol n after genotoxic stress in primary cells, associated with increased ability to deal with the stalled replication fork, and consequently to DNA replication restart and cell survival. In addition, we detected a difference in genomic stability in immunoglobulin genes in aged XP-V patients in comparison to both young patients and age-matched controls, showing the absence of this polymerase may be linked to increased genomic instability in these genes

A via de Reparo por Excisão de Nucleotídeos (NER) é responsável pelo reparo das lesões causadas pela luz ultravioleta (UV) e de outras lesões capazes de distorcer a dupla hélice, bloqueando a replicação e a transcrição. Os pacientes que apresentam as síndromes recessivas raras Xeroderma Pigmentosum (XP), tricotiodistrofia (TTD) e síndrome de Cockayne (CS) possuem mutações em algum dos 11 genes relacionados ao NER e à transcrição basal. Mutações na proteína XPD levam ao surgimento de diferentes fenótipos: XP, TTD, XP/CS ou COFS (Cerebro-Oculo-Facio-Skeletal Syndrome), uma forma rara de CS. Os pacientes XP apresentam alta incidência de câncer de pele, o que não ocorre com os pacientes TTD e CS, além de poderem apresentar perda neuronal progressiva, enquanto todos os CS e TTD apresentam uma diminuição na mielinização do cérebro. As neuropatologias são provavelmente associadas a problemas no reparo de danos endógenos no DNA das células nervosas. Diversos trabalhos mostraram o envolvimento do NER no reparo desses danos, os quais pensava-se serem reparados apenas por outro mecanismo, o Reparo por Excisão de Base. Neste trabalho mostramos que fibroblastos de pacientes XP-D, XP-D/CS e TTD, portadores de mutações em XPD, são sensíveis ao estresse oxidativo induzido pelo tratamento com azul de metileno fotoativado, apresentando bloqueio prolongado no ciclo celular e permanência da sinalização de danos ao DNA. A complementação das diferentes linhagens com o gene XPD/ERCC2 foi capaz de restaurar a sobrevivência celular. Foram detectadas diferenças importantes na capacidade de reparo/retomada da transcrição após danos gerados por estresse oxidativo em DNA plasmidial, além da ativação de vias diferentes de morte celular: fibroblastos XP-D apresentam maior capacidade de reparo e apresentam morte por apoptose após estresse oxidativo, enquanto os fibroblastos XP-D/CS e TTD apresentam menor capacidade de reparo ativação de mais de uma via de morte celular (apoptose e necrose), diferenças que podem estar ligadas ao fenótipo dos pacientes. Mutações no gene codificante para a DNA polimerase n, POLH, estão associadas à forma variante de XP (XP-V). Pol n é uma polimerase especializada na síntese translesão (TLS) de fotoprodutos, além de estar implicada na TLS de outros tipos de lesões como bases oxidadas, e em vias não relacionadas à TLS como a hipermutação somática e à replicação de regiões de DNA com arquiteturas não-canônicas. Neste trabalho mostramos que os fibroblastos de pacientes XP-V apresentam sensibilidade ao estresse oxidativo. Mostramos uma indução da proteína pol n em fibroblastos primários após danos genotóxicos, associada ao aumento da capacidade de lidar com a parada na forquilha de replicação, possibilitando a continuidade da replicação do DNA e ao aumento da sobrevivência celular. Mostramos uma diferença na estabilidade genômica nos genes das imunoglobulinas dos pacientes XP-V idosos em comparação com os pacientes jovens e controles de idade pareada, mostrando que a ausência dessa polimerase pode estar ligada ao aumento da instabilidade genômica nesses genes / The Nucleotide Excision Repair (NER) pathway is responsible for the repair of UV photoproducts and other bulky lesions that block both replication and transcription. Patients with the rare recessive disorders Xeroderma Pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne Syndrome (CS) carry mutations in one of the 11 NER genes, linked to repair and basal transcription. Mutations in XPD lead to different phenotypes: XP, TTD, XP/CS or COFS (Cerebro-Oculo-Facio-Skeletal Syndrome), a rare form of CS. XP patients have high incidence of skin cancer, which does not occur in TTD or CS patients, although ther may present neurodegeneration, while all CS and TTD patients have neurodevelopmental symptoms linked to dysmielynation. The pathology of these neurological diseases is probably associated with deficient repair of DNA lesions in nervous cells, generated by endogenous processes. Many groups including ours have demonstrated the involvement of NER in the repair of these lesions, previously thought to be exclusively repaired by Base Excision Repair. In this work we show high sensitivity of both primary and transformed XP-D, XP-D/CS and TTD human fibroblasts in response to oxidative stress generated by photoactivated methylene blue, with prolonged cell cycle arrest and DNA damage signaling. The complementation of the three different cell lines with the XPD/ERCC2 gene was able to restore cell survival. We detected important differences in repair capacity/transcription resumption after damage generated by oxidative stress in plasmid DNA, besides the activation of different cell death pathways: XP-D cells have higher repair capacity and die by apoptosis, while XP-D/CS and TTD cells have little repair capacity and activate more than one death pathway (apoptosis and necrosis). We believe these differences can be related to the patients\' phenotypes. Mutations in DNA polymerase n coding gene, POLH, are associated with the variant form of XP (XP-V). Pol n is a translesion synthesis (TLS) polymerase specialized in the TLS past CPD photoproducts, besides other lesions like oxidized bases, and in other processes like somatic hypermutation and DNA replication in structured regions. In this work we show XP-V human fibroblasts are sensitive to oxidative stress. We detected an induction of pol n after genotoxic stress in primary cells, associated with increased ability to deal with the stalled replication fork, and consequently to DNA replication restart and cell survival. In addition, we detected a difference in genomic stability in immunoglobulin genes in aged XP-V patients in comparison to both young patients and age-matched controls, showing the absence of this polymerase may be linked to increased genomic instability in these genes