Cells in our body respond to genotoxic stress by activation of a conserved DNA damage response pathway (DDR). Depending on the level DNA damage, DDR signaling promotes temporary cell cycle arrest (checkpoint), permanent growth arrest (senescence) or programmed cell death (apoptosis). Checkpoints prevent progression through the cell cycle and facilitate repair of damaged DNA. DDR represents an intrinsic barrier preventing genome instability to protect cells against cancer development. WIP1 (encoded by PPM1D) phosphatase is a major negative regulator of DDR pathway and is essential for checkpoint recovery. This thesis contributed to the understanding of molecular mechanisms of WIP1 function and revealed how WIP1 can be involved in tumorigenesis. Firstly, we described that WIP1 protein levels decline during mitosis by APC-Cdc20 dependent proteasomal degradation. WIP1 is phosphorylated at multiple residues which inhibit its enzymatic activity. We propose that inhibition of WIP1 in mitosis allows sensing of low levels of DNA damage that appear during unperturbed mitosis. Further, we identified novel gain-of-function mutations of PPM1D which result in expression of C-terminally truncated WIP1. These truncated WIP1 variants are enzymatically active and exhibit increased protein stability. As result, cells...

Vatten är en av de vanligaste skadeorsaken i Svenska byggnader. Det inträffar 100 000 vattenskador varje år och dessa kostar 5-6 miljarder att åtgärda. Detta problem har legat till grund för vårt arbete där vi frågar oss: ”Hur kan antalet vattenskador minskas?” Vi har försökt att besvara frågan med hjälp av statistik från Vattenskadecentrum, intervjuer med branschfolk och studier av branschregler. Det som framkommit är att badrum och kök är de mest drabbade utrymmen. Efter år 2011 har andelen skador i kök blivit fler än de i badrum. Orsaken till detta är ökningen av trycksatta vattenledningar i kök samt avsaknaden av krav på tätskikt och golvbrunn. Trots att vattenanvändningen i badrum, relativt sätt, har ökat har andelen skador minskat tack vare förbättrad teknik, strängare normer och bättre material. Vi tror att om antalet vattenskador ska minskas bör branschregler för kök kompletteras, utbilda och auktorisera fler företag samt upplysa fastighetsägare om vikten av fackmässigt byggande. / Water is one of the most common cause of injuries in Swedish buildings. It occurs 100 000 water damages every year and it costs 5-6 billions to repair. This problem has been the basis for our report with the question: “How can the number of water damages be reduced?” We have tried to answer the question using data from Vattenskadecentrum (Water damage center), interviews with professionals and studies of regulations. What has appeared is that the bathroom and kitchen are the most affected areas. After 2011, the quantity of water damages in the kitchen has passed the quantity of water damages in the bathroom. This is due to the increased number of pressurized water pipes in the kitchen and the absence of requirements for waterproofing and draining gutter. Despite the change of water usage in bathrooms, the percentage of water damages in bathrooms has decreased thanks to improved technique and materials. To reduce the number of water damages should regulations for the kitchen enlarge, train more in the industry and inform property owners about the importance of professionally-building.

The purpose of this research was to quantify the strength of novel composite repair methods for thin-walled composite structures. Carbon/epoxy plates were manufactured and repairs were made at Gloyer-Taylor Laboratories. At BYU, specimens were damaged in a controlled and repeatable process. Three damage modes were implemented: impact, groove, and abrasive damage. Tensile strength tests were performed on control, damaged, and repaired specimens. Four 24 x 24 in (60 x 60 cm) carbon/epoxy plates were received. Each plate was made up of seven plies cured together with epoxy resin for a nominal total thickness of 0.04 in (1.02 mm). The thickness, however, was not uniform: each plate had a smooth side and a wavy side. This resulted in inconsistent damage depth. The plates were cut at BYU using a water-jet cutter into 1 in. (25.4 mm) wide by 8 in. (203.2 mm) long test specimens. Test specimens were grouped into four categories: control specimens, specimens inflicted with damage by machining a shallow groove ranging from 0.012 — 0.018 in. (0.30 — 0.46 mm) deep, specimens inflicted with an abrasive-type damage ranging from 0.006 — 0.012 in. (0.15 — 0.30 mm) deep, and specimens subjected to impact damage ranging from 1.47 — 3.23 J. Five specimens were placed in the control group. Ten specimens were placed in each of the remaining damage groups. All ten specimens were damaged, but only five of each were sent to be repaired. The randomization of the thickness variable was prevented by the desire to repair damaged specimens as a group with a single repair rather than performing repairs on every individual specimen. The stress-strain behavior confirm the control specimens generally exhibited the best overall behavior, as expected. Most damaged specimens, including the repaired specimens, exhibited lower ultimate stress than the undamaged control specimens. The repaired specimens exhibited a higher initial stiffness than either the control or damaged specimens, due to the stiffness of the composite patch. Although repaired specimens should exhibit higher strength than damaged specimens, but this however, was not always the case. In particular, repairs did not improve the ultimate strength of the specimens damaged by abrasion. Correlations between the different damage types were developed, relating damage intensity and strength was approximately. This suggests further investigation is needed.

With the export of coal being more lucrative than selling coal to South African power producers, power station operators might consider accepting lower-quality coal. While the impact lower quality coal has on cycle efficiency is understood, the influence it has on equipment reliability and lifetime is often not understood. This study focusses on addressing the question of how different characteristics of coal influences different damage mechanisms of common power station equipment. The results are translated into a reference framework that can be used when coal quality variation is expected. The influence of coal calorific value and ash content has on air-heater element erosion was evaluated. This was accomplished by establishing a correlation between calorific value and ash content of coal from a specific colliery; this was then used to calculate the mass of fly ash and flue gas produced when burning enough coal to satisfy the boiler load. An erosion model was then used along with historical coal quality and air heater erosion history to develop and fit a model for full boiler load. The model was verified against data not used during the development of the model, and a seemingly good prediction was made when compared to the measured result. The calorific value of the coal in the model was varied for a hypothetical situation; this indicated that as calorific value decreases the erosion of air heater elements increases. The influence abrasiveness index has on mill liners was also investigated as part of this study. Historical liner ultrasonic thickness and coal abrasiveness index results were used to fit a mathematical formula. The results indicate that for the ball mills at the power station used in the case study, the abrasiveness index did not have a significant influence on the wear rate of mill liners. The relationship was established to be directly proportional to increased abrasiveness index resulting in an increased wear rate. The final two case studies that form part of this overall study were focussed on boiler temperature variations as a result of variation in coal calorific value and establishing the impact coal “hang-ups” have on the lifetime of a drum reclaimer. The first of these two case studies was completed by creating a mathematical thermo-hydraulic model of a hypothetical boiler and calculating the effect calorific value would have on the boiler temperature distribution. The results were then compared to temperature-related damage mechanisms; the comparison indicated that a variation in calorific value, whether up or down from the designed value would be negative for overall boiler health. The final case study was not completed due to the unavailability of related equipment. A full description of the envisaged study is provided. / Dissertation (MEng)--University of Pretoria, 2019. / Mechanical and Aeronautical Engineering / MEng / Unrestricted

Chromosomal translocation is a characteristic feature of human lymphoid malignancies and a driver of the initiation and progression of the disease. They arise from the mis-repair of physiological DNA double-strand breaks (DSBs) generated during the assembly and subsequent modifications of the antigen receptor gene loci, namely V(D)J recombination and class switch recombination (CSR). Mammalian cells have three DSB repair pathways –classical non-homologous end-joining (cNHEJ), alternative end-joining (A-EJ), and homologous recombination. DNA end-resection that generates a single-strand 3’ overhang is a critical regulator for the repair pathway choice. Specifically, localized end-resection prevents cNHEJ and exposes flanking microhomology (MH) to promote error-prone A-EJ. In addition to DNA repair, DNA end-resection generates extended single-strand DNA, which activates the ATR-mediated cell cycle checkpoint and indirectly contributes to genomic integrity. The central goal of my thesis research is to investigate the physiological role of DNA end-resection initiation in lymphocyte development and lymphomagenesis. DNA end-resection in mammalian cells is mostly initiated by the endonuclease activity of MRE11-RAD50-NBS1 (MRN) complex aided by CtIP. In addition, MRN protein also recruits EXO1 and DNA2 nucleases in combination with Top3 helicase complex for more extensive resection. The CtIP protein is essential for the endonuclease activity of the MRN complex that initiates DNA end-resection. CtIP is essential for embryonic development. Here I utilized B cell-specific conditional deletion models and loss-of-function mutations to investigate the role and regulation of CtIP and CtIP-mediated DNA end-resection in lymphocyte development and tumorigenesis. The level and extent of CtIP-mediated resection are tightly regulated. For the first aim, we applied the ATAC-Seq and EndSeq methods to test whether chromatin accessibility determines the level of DNA end-resection. Specially, we found that chromatin-bound DNA damage response factors – H2AX and 53BP1- reduced the accessibility of the DNA around the DSBs and antagonized end-resection. Our data also suggest that during DNA damage response, the nucleosome-free or accessible regions are more prone to secondary DNA breakages. Mechanistically, the preferential vulnerability is correlated with the availability of chromatin-bound DNA damage response factor 53BP1, which protects the nucleosome covered region at the price of the nucleosome-free regions. The work provides one explanation for tissue and cell type-specific translocations in transcriptionally active regions and super-enhancers. For the second and third aims, I investigated the role of CtIP and CtIP-mediated end-resection in lymphocyte development and lymphomagenesis in vivo using the conditional deletional CtIP allele and a phosphorylation-deficient CtIP-T855A mutant. T855 phosphorylation promotes end-resection but is not essential for cellular viability. I identified a sequence-context-dependent role of CtIP and end-resection in A-EJ mediated repair. We found that the reduced level of end-resection did not alter the frequency of the A-EJ mediated joining during B cell CSR, nor the levels of micro-homology at the junction, a defining feature of A-EJ mediated repair. These findings, for the first time, showed that DNA end-resection is not essential for A-EJ-mediated chromosomal DSBs repair nor for the generation of MH at the junction in vivo. This unexpected observation also highlights a tissue- and cell type-specific regulation of A-EJ and the importance of sequence context for A-EJ. Moreover, we found that ATM kinase suppresses A-EJ mediated translocation and reported the very first cell cycle-dependent analyses of CSR junctions. In cNHEJ-deficient B cells (e.g., Xrcc4- or DNA-PKcs- deficient), the A-EJ pathway is responsible for both the residual CSR events and the generation of the oncogenic IgH-Myc chromosomal translocations. In the last chapter, I determined how CtIP contributes to oncogenesis using the CtIP-T855A phospho-deficient mouse model. The result showed that CtIP T855 phosphorylation is critical for the neonatal development of Xrcc4-/-p53-/- mice and IgH-Myc translocation driven lymphomagenesis in DNA-PKcs-/-Tp53-/- mice. Mechanistically, phospho-deficient CtIP compromises the extent of end-resection without affecting the initiation. Reduced end-resection in CtIP-T855A mice and cells attenuated G2/M checkpoints and reduced the tolerance to the oncogene-induced replication stress, thereby limit lymphomagenesis. Collectively, our data provided the first in vivo characterization for the role of CtIP and its related end-resection pathway in lymphocyte development and lymphomagenesis. The results highlight the importance of end-resection for checkpoint maintenance (§ 4) and the context-dependent regulation of A-EJ and DNA repair pathway choice in vivo (§ 3), explaining why A-EJ is more robust at the repetitive switch regions. Finally, the application of HTGTS, EndSeq, and ATAC-Seq technologies in lymphocyte-specific gene rearrangements markedly improved the analysis depth and sensitivity while reducing the cost of repair-junction sequencing, allowing the quantitative detection of subtle changes and additional mechanistic insights. Specifically, we showed that end-resection could be regulated at the level of chromatin accessibility, which is determined by both baseline chromatin occupancy and DNA damage-induced changes (§ 2). These findings provide one explanation for the tissue and cell type-specificity of translocation targeting. These techniques can be used to analyze the impact of other DNA repair factors during lymphocyte development and lymphomagenesis and in translocation in general.

A method that can be used to detect damage in structures is developed. This method is based on the convexity of the geometric interpretation of the eigenvalue problem for undamped positive definite systems. The damage detection scheme establishes various damage scenarios which are used as failure sets. These scenarios are then compared to the structure's actual response by measuring the natural frequencies of the structure and using a Euclideian norm. Mathematical models were developed for application of the method on a cantilever beam. Damage occurring at a single location or in multiple locations was estalished and studied. Experimental verification was performed on serval prismatic beams in which the method provided adequate results. The exact location and extent of damage for several cases was predicted. When the method failed the prediction was very close to the actual condition in the structure. This method is easy to use and does not require a rigorous amount of instrumentation for obtaining the experimental data required in the detection scheme. / Ph. D.

This work aimed to better understand the early molecular events occasioned in human thyrocytes following exposure to genotoxic agents than can lead to thyroid mutagenesis and cancer. Similar in vitro data in human physiological models remain scarce.The reported incidence of papillary thyroid carcinoma (PTC), has been increasing worldwide but the pathogenesis of sporadic PTC remains unravelled. H2O2 has long been postulated by the host laboratory and by other groups as a potential thyroid mutagen since it is capable to cause DNA damage and it affects γ radiation-induced DNA damage in thyrocytes. Thyrotropin (TSH) has recently been advocated as a potential risk factor for PTC: it has been associated with advanced stage disease and with progression of microcarcinoma during active surveillance. TSH signalling was found to be essential for BRAF-induced thyroid carcinogenesis in mouse models. Radiation (γ and β) is the only clearly established environmental risk factor for PTC; the cancer relative risk is rising linearly beyond a threshold of 100mGy thyroid absorbed dose. We studied in human thyrocytes in primary cultures the early molecular events following 131I exposure (β radiation) in comparison to γ radiation and H2O2 exposure, and their modulation by TSH. We assessed cell survival, DNA damage, DNA repair, gene expression, cell proliferation and apoptosis. Although we globally observed that the thyrocyte responses following exposure to β, γ radiation or H2O2 showed similarities, TSH, unlike other proliferative agents tested, specifically increased DNA damage both in non-exposed and in 131I-exposed thyrocytes. TSH did not influence γ radiation- or H2O2-induced damage. The effect of TSH on DNA damage in non-exposed thyrocytes decreased after incubation with an antioxidant agent and in 131I-exposed thyrocytes was partially alleviated after inhibition of iodide uptake. Therefore, in our experimental conditions, TSH seemed to predispose thyroid cells to greater DNA damage after exposure to 131I via Gαq-mediated increase in ROS/H2O2 levels, independent of its action on iodide uptake or proliferation status. DNA repair timing was similar between β, γ radiation and H2O2. Both β and γ radiation resulted in an extended thyroid cell cycle arrest but no apoptosis. In contrast, H2O2 did not appear to affect cell cycle at the same extent.This works includes the first, to our best knowledge, RNA sequencing to obtain the gene expression profile of human thyrocytes following 131I exposure. Overall transcriptional responses of thyrocytes exposed to 131I, γ radiation and H2O2 overlapped. At this stage, we were not able to attribute a distinct molecular signature to each agent, pointing that they probably employ similar cellular toxicity mechanisms. Regulated genes were involved in inflammatory response, cytokine signaling, DNA repair, apoptosis and cell cycle. Again, TSH yielded a more prominent transcriptomic response, both in number and in expression level of regulated transcripts, exclusively following 131I exposure. Better understanding of the early stages of thyroid carcinogenesis could lead to a more precise, personalized management of thyroid cancer patients and even in novel therapeutic strategies. / Doctorat en Sciences médicales (Médecine) / info:eu-repo/semantics/nonPublished

Thesis (M. Agric. (Plant Production)) -- University of Limpopo, 2019 / Phytonematicides have allelochemicals as active ingredients and could be highly phytotoxic on crops being protected against nematode damage. In order to avoid phytotoxicity, the application concentration, technically referred to as mean concentration stimulation point (MCSP), along with the application interval, have to be empirically established. The Curve-fitting Allelochemical Response Data (CARD) computer-based model was adopted at the Green Biotechnologies Research Centre of Excellence (GBRCE) for developing the MCSP. The MCSP is computed from the CARD-generated biological indices and was technically defined as a phytonematicide concentration that could manage the nematode population densities without causing phytotoxicity to the test crop and it is plant-specific. The MCSP and application interval had been empirically established for different crops, but they had not been established for sweet potatoes. Therefore, the objective of the study was to determine the MCSP for Nemarioc-AL phytonematicide on Meloidogyne javanica-infected sweet potato cv. ꞌBopheloꞌ and its application interval. Sweet potato cuttings were planted in 25-cm diameter plastic bags containing steam-pasteurised loam soil and Hygromix at 3:1 (v/v) ratio. Each plant was inoculated with 5 000 eggs and second-stage juveniles (J2) of M. javanica, with seven treatments, namely, 0, 2, 4, 8, 16, 32 and 64% Nemarioc-AL phytonematicide, arranged in a randomised complete block design, with five replicates. At 56 days after the initiation of treatment, the MCSP values for plant variables and plant physiology variables were 1.92 and 3.08% Nemarioc-AL phytonematicide, respectively. The overall sensitivity values for plant variables and plant physiology variables were 0 and 1 unit, respectively, showing that the sweet potato cv. ꞌBopheloꞌ was highly sensitive to the product. Nematode variables with increasing concentrations of Nemarioc-AL phytonematicide exhibited positive and quadratic relations. The life cycle of M. javanica and the derived MCSP were used to empirically establish the application interval. Briefly, the location and most materials and methods were as outlined above except that ‘weeks-per-month-of-30 days’, with the MCSP being applied on 0, 7.5, 15, 22.5 and 30 days (0, 1, 2, 3 and 4 weeks) serving as treatments, replicated eight times. At 56 days after the treatments, plant variables and increasing application interval exhibited positive quadratic relations with the average of 2.55 ‘week of-30-day-month’ translating to 19 days (2.55/4 × 30), with nematode variables exhibiting negative quadratic relationships. In conclusion, when the MCSP of Nemarioc AL phytonematicide on sweet potato cv. 'Bophelo' at 1.92% was applied every 19 days, it would not be phytotoxic, but it would be able to suppress nematode population densities of M. javanica. The MCSP for essential nutrient elements could be reduced to that of plant growth variables, since the products are not intended for use as fertilisers.

Background and aims: Hypertension is a public health problem and a major reason for hospitalisation and death. In Mozambique, low levels of detection, treatment and control have been described. However, data on target-organ damage and associated clinical conditions is lacking. We therefore aimed at characterising the clinical profile of patients with severe hypertension, describing the pattern of target organ damage and determining the outcomes at 6-month follow-up. Methods: We designed a prospective descriptive cohort study to assess adult patients with severe hypertension defined according to the Joint National Committee VII guidelines. The study was conducted from July 2015 to May 2017 at Mavalane General Hospital in Maputo-Mozambique. Patients were characterized through physical examination, laboratory profile, electrocardiography, and echocardiography, and followed for six months to assess occurrence of complications such as hypertensive heart failure, stroke, renal failure, hospital admission and death. Data were analysed using SPSS software version 20.0. The study was approved by the National Bioethics Committee for Health of Mozambique. Results: We studied 116 subjects (111 [95.7%] black; women 81 [70%]). Women were slightly younger than men (mean 57 years vs 59 years); 18 (15.5%) patients were younger than 44 years. The risk profile of the studied population included obesity (46; 42.5%); dyslipidaemia (59; 54.1%); diabetes (10; 8.6%) and smoking (8; 6.9%). At baseline, mean values for systolic and diastolic blood pressure were 192.3 ± 23.6 and 104.2 ± 15.2, respectively. The most frequent target-organ damage were left atrial enlargement in 91 (88.3%) with atrial fibrillation in 9 (7.9%); left ventricular hypertrophy in 57 (50.4%); hypertensive retinopathy in 30 (26. 3%) and renal damage in 29 (25.7%) subjects. Major events during 6-month follow-up were hospitalisations (12; 10.3%) and death (10; 8.6%). Renal damage (4; 4.2%), stroke (4; 3.4%) and heart failure (2; 1.7%) were the most common complications occurring over the follow up period. Conclusion: Severe and complicated hypertension affects young people with higher incidence of obesity, diabetes and smoking than that found in general population. High occurrence of target organ damage is found at baseline, particularly heart damage, renal lesion and stroke. On follow up, severe hypertension is associated with high number of hospitalisations and high case-fatality rate. Moreover, renal damage, stroke and hypertensive heart disease were common complications on follow up. Further research is needed to understand the determinants of these poor outcomes.

It is a frequent occurrence in accident cases involving alleged brain injury and attendant damage suits, for the defendant's attorney to charge the plaintiff in the case with malingering. At some time in the court proceedings it i.s also common that the plaintiff's psychologist will testify to the court that his client's brain damage is genuine, not feigned. but heretofore, clinicians have been able to speak to the court only from their own background of clinical experience, and clinicians have been known to disagree. They have not been able to refer to a body of research that has addressed itself to the question, Can Ss simulate brain damage on the Bender-Gestalt Test? This issue is particularly significant since many clinicians use the Bender to assess cases in which brain damage is suspected. Since the thrust of this study was exploratory, the answer to this experimental question is not totally conclusive. However, it was determined that college Ss of at least normal intelligence who did not present evidence of brain damage on an initial Bender screening could not simulate traumatic brain damage. Although there is little reason to believe that non-organic Ss from other kinds of educational backgrounds (excluding, possibly, Ss who are extremely knowledgeable about the Bender), ages and levels of intelligence could simulate traumatic brain damage successfully, this possibility exists and should be researched. The project consisted of a pilot study and a main study. In the pilot study 18 volunteers from an upper division psychology class were tested with a Bender in a group situation under standard instructions. Four weeks later they were . asked to simulate brain damage on the Bender. The test records of 18 organic Ss were used to form a criterion group. An ABPP certified clinical psychologist then attempted to sort the malingerers from the organics (Sort 1) and the normals from the organics (Sort 2). On the first sort, 2 of the 18 Ss in each group were missorted. On the second sort, 1 organic and 2 normals were missorted. The resulting Phi coefficients were .78 and .83, respectively. Since existing quantitative sorting methods (Le., the Pascal-Suttell system and the Canter system) were not able to validly differentiate malingerers from organics, it became necessary to spell out the implicit criteria which the clinician used as he performed his sorts. An analysis of the criteria then revealed that all of the missorts, except 1 organic S, involved confusions of "normal" Ss who were either borderline organics or mildly organic with organic S5 who were mildly organic. The main study was necessary to replicate the findings obtained from the pilot study since the criteria devised therefrom were formulated 'ex post facto.' The results obtained were generally comparable to those from the pilot study. In the main study, a second clinician independently sorted the groups in order to provide a reliability check on the sorting procedure. An analysis of the sorting decisions resulting from the criteria-based sorting procedure indicated that the sorting decisions of the 2 clinicians concurred on 84% of the protocols in the malingerer-organic sort and on 94% of the records in the normal-organic sort. A sort-resort operation by the first clinician on the malingerer-organic sort with one day intervening resulted in 100% agreement between his judgments.