Sealing Ability of Nano-fast Cement vs. Mineral Trioxide Aggregate as Retrograde Apical Plugs: An In-vitro Microleakage Study

Introduction: Apical surgery aims to eradicate the apical part of the root and the lesion to enhance the healing. The sealing ability of retrograde filling material is an essential factor affecting the success rate of the surgery. Mineral trioxide aggregate (MTA) is the gold standard of retrograde filling materials, with approved sealing capability and biocompatibility. Newly introduced root repair material with an approved antibacterial effect similar to MTA is Nano-fast cement (NFC) which should be investigated for its sealing ability. This study aimed to evaluate the sealing ability of NFC vs. MTA. Materials and Methods: Root apices of 48 single-rooted teeth were resected at 90 degrees and were prepared at 3 mm depth. The teeth were randomly divided into 2 experimental groups (n=21), negative control group (n=3), and positive control group (n= 3). MTA and NFC plugs were condensed as retrograde filling material.  The samples were evaluated by a modified fluid filtration device for 1 hour. The measurement was conducted at 24 h, 1, and 3 months. Data were analyzed by Friedman Test and Kruskal-Wallis test. Results: According to the results, NFC at 3-months interval showed the least microleakage, and MTA had the highest at the baseline. However, the results between the two groups were not statistically significant in all intervals. NFC reached the ideal sealing ability within 1 month, which was reached for MTA after 3 months. Conclusions: The results of this in vitro study showed that the microleakage value of NFC is comparable to MTA. In light of current findings, NFC shows characteristics of a suitable calcium silicate-based cement. Further clinical researches are needed to introduce the NFC as retrograde apical plug or for other endodontic applications

The importance of having two X chromosomes

Historically, it was thought that the number of X chromosomes plays little role in causing sex differences in traits. Recently, selected mouse models have been used increasingly to compare mice with the same type of gonad but with one versus two copies of the X chromosome. Study of these models demonstrates that mice with one X chromosome can be strikingly different from those with two X chromosomes, when the differences are not attributable to confounding group differences in gonadal hormones. The number of X chromosomes affects adiposity and metabolic disease, cardiovascular ischaemia/reperfusion injury and behaviour. The effects of X chromosome number are likely the result of inherent differences in expression of X genes that escape inactivation, and are therefore expressed from both X chromosomes in XX mice, resulting in a higher level of expression when two X chromosomes are present. The effects of X chromosome number contribute to sex differences in disease phenotypes, and may explain some features of X chromosome aneuploidies such as in Turner and Klinefelter syndromes

The Effects of Perinatal Testosterone Exposure on the DNA Methylome of the Mouse Brain Are Late-Emerging

Background The biological basis for sex differences in brain function and disease susceptibility is poorly understood. Examining the role of gonadal hormones in brain sexual differentiation may provide important information about sex differences in neural health and development. Permanent masculinization of brain structure, function, and disease is induced by testosterone prenatally in males, but the possible mediation of these effects by long-term changes in the epigenome is poorly understood. Methods We investigated the organizational effects of testosterone on the DNA methylome and transcriptome in two sexually dimorphic forebrain regions—the bed nucleus of the stria terminalis/preoptic area and the striatum. To study the contribution of testosterone to both the establishment and persistence of sex differences in DNA methylation, we performed genome-wide surveys in male, female, and female mice given testosterone on the day of birth. Methylation was assessed during the perinatal window for testosterone\u27s organizational effects and in adulthood. Results The short-term effect of testosterone exposure was relatively modest. However, in adult animals the number of genes whose methylation was altered had increased by 20-fold. Furthermore, we found that in adulthood, methylation at a substantial number of sexually dimorphic CpG sites was masculinized in response to neonatal testosterone exposure. Consistent with this, testosterone\u27s effect on gene expression in the striatum was more apparent in adulthood. Conclusion Taken together, our data imply that the organizational effects of testosterone on the brain methylome and transcriptome are dramatic and late-emerging. Our findings offer important insights into the long-term molecular effects of early-life hormonal exposure

The Sex Chromosome Trisomy mouse model of XXY and XYY: metabolism and motor performance

BACKGROUND: Klinefelter syndrome (KS), caused by XXY karyotype, is characterized by low testosterone, infertility, cognitive deficits, and increased prevalence of health problems including obesity and diabetes. It has been difficult to separate direct genetic effects from hormonal effects in human studies or in mouse models of KS because low testosterone levels are confounded with sex chromosome complement. METHODS: In this study, we present the Sex Chromosome Trisomy (SCT) mouse model that produces XXY, XYY, XY, and XX mice in the same litters, each genotype with either testes or ovaries. The independence of sex chromosome complement and gonadal type allows for improved recognition of sex chromosome effects that are not dependent on levels of gonadal hormones. All mice were gonadectomized and treated with testosterone for 3 weeks. Body weight, body composition, and motor function were measured. RESULTS: Before hormonal manipulation, XXY mice of both sexes had significantly greater body weight and relative fat mass compared to XY mice. After gonadectomy and testosterone replacement, XXY mice (both sexes) still had significantly greater body weight and relative fat mass, but less relative lean mass compared to XY mice. Liver, gonadal fat pad, and inguinal fat pad weights were also higher in XXY mice, independent of gonadal sex. In several of these measures, XX mice also differed from XY mice, and gonadal males and females differed significantly on almost every metabolic measure. The sex chromosome effects (except for testis size) were also seen in gonadally female mice before and after ovariectomy and testosterone treatment, indicating that they do not reflect group differences in levels of testicular secretions. XYY mice were similar to XY mice on body weight and metabolic variables but performed worse on motor tasks compared to other groups. CONCLUSIONS: We find that the new SCT mouse model for XXY and XYY recapitulates features found in humans with these aneuploidies. We illustrate that this model has significant promise for unveiling the role of genetic effects compared to hormonal effects in these syndromes, because many phenotypes are different in XXY vs. XY gonadal female mice which have never been exposed to testicular secretions

Modulation of T Cell Function by Combination of Epitope Specific and Low Dose Anticytokine Therapy Controls Autoimmune Arthritis

Innate and adaptive immunity contribute to the pathogenesis of autoimmune arthritis by generating and maintaining inflammation, which leads to tissue damage. Current biological therapies target innate immunity, eminently by interfering with single pro-inflammatory cytokine pathways. This approach has shown excellent efficacy in a good proportion of patients with Rheumatoid Arthritis (RA), but is limited by cost and side effects. Adaptive immunity, particularly T cells with a regulatory function, plays a fundamental role in controlling inflammation in physiologic conditions. A growing body of evidence suggests that modulation of T cell function is impaired in autoimmunity. Restoration of such function could be of significant therapeutic value. We have recently demonstrated that epitope-specific therapy can restore modulation of T cell function in RA patients. Here, we tested the hypothesis that a combination of anti-cytokine and epitope-specific immunotherapy may facilitate the control of autoimmune inflammation by generating active T cell regulation. This novel combination of mucosal tolerization to a pathogenic T cell epitope and single low dose anti-TNFα was as therapeutically effective as full dose anti-TNFα treatment. Analysis of the underlying immunological mechanisms showed induction of T cell immune deviation

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

The genetics and epigenetics of sex differences in the brain.

The major drivers underlying sexually dimorphic brain development are gonadal hormones, namely testosterone (T). During the perinatal sensitive period, a time when the embryonic brain is maximally sensitive to changes in the levels of gonadal hormones, exposure to T has permanent organizing effects on the brain, the molecular basis of which is not known. One potential mechanism for the long term permanence may be DNA methylation. To examine the contribution of epigenetic mechanisms to both the establishment and maintenance of sex differences, I compared the methylomes of male, female, and female mice treated with testosterone. Methylation maps were generated for sexually dimorphic brain regions such as the striatum at postnatal day 4 (PN4) during the sensitive period and PN60 during adulthood using reduced representation bisulfite sequencing. I found that testosterone altered the methylation of a few genes during the sensitive period but a much greater number in adulthood. I next investigated whether administration of a single dose of testosterone to females on the day of birth could induce a shift in DNA methylation from a female-typical to a more male-typical pattern. The results demonstrated that the masculinizing effect of testosterone was mostly evident at PN60 but not at PN4. This observation provided a new perspective on the mechanisms underlying organizational effects of testosterone because contrary to the expectation that testosterone leaves a strong, stable imprint shortly after exposure, testosterone effects on DNA methylation were not immediately evident but emerged later. Based on these data, I concluded that sex differences in methylation are not the result of the immediate early actions of testosterone on the brain. Rather, the neural molecular patterns found in adults are conditioned by early hormonal exposures, the effects of which might emerge over a period of time. Gene Ontology analysis on the set of genes whose methylation was altered by testosterone revealed a significant enrichment of genes belonging to signaling components associated with dopamine modulation as well as movement disorders that display a male-bias. These data are consistent with striatum's role in regulation of movement.In addition to assessing the contribution of hormones to brain sexual differentiation, I also investigated the impact of sex chromosomes on sex differences in brain and behavior. To test for sex chromosome effects, I used the four core genotypes mouse model and found sex differences in expression of a subset of striatal genes caused by XX vs. XY differences in mice with the same gonadal type. Moreover, comparison of animals with different numbers of sex chromosomes in a novel mouse model of Klinefelter Syndrome (KS), the Sex Chromosome Trisomy Model, indicated that presence of an additional X chromosome and/or its interaction with the Y in XXY male mice can contribute to some of the behavioral and molecular phenotypes observed in KS. Interestingly, analysis of striatal transcriptome in KS mice revealed a feminized molecular signature in the brain of KS male mice. Such information is crucial knowledge in elucidating not only the pathophysiology of KS, but also the origin of sex differences in brain and behavior. Altogether, my work demonstrates the significance of genetics and epigenetics in the process of brain development as it relates to sex. The results presented in this dissertation suggest that (1) the sex chromosomes carry genes that could influence brain function and behavior; and (2) the long lasting effects of steroid hormones on the brain could be mediated by epigenetic mechanisms such as DNA methylation

The genetics and epigenetics of sex differences in the brain.

The major drivers underlying sexually dimorphic brain development are gonadal hormones, namely testosterone (T). During the perinatal sensitive period, a time when the embryonic brain is maximally sensitive to changes in the levels of gonadal hormones, exposure to T has permanent organizing effects on the brain, the molecular basis of which is not known. One potential mechanism for the long term permanence may be DNA methylation. To examine the contribution of epigenetic mechanisms to both the establishment and maintenance of sex differences, I compared the methylomes of male, female, and female mice treated with testosterone. Methylation maps were generated for sexually dimorphic brain regions such as the striatum at postnatal day 4 (PN4) during the sensitive period and PN60 during adulthood using reduced representation bisulfite sequencing. I found that testosterone altered the methylation of a few genes during the sensitive period but a much greater number in adulthood. I next investigated whether administration of a single dose of testosterone to females on the day of birth could induce a shift in DNA methylation from a female-typical to a more male-typical pattern. The results demonstrated that the masculinizing effect of testosterone was mostly evident at PN60 but not at PN4. This observation provided a new perspective on the mechanisms underlying organizational effects of testosterone because contrary to the expectation that testosterone leaves a strong, stable imprint shortly after exposure, testosterone effects on DNA methylation were not immediately evident but emerged later. Based on these data, I concluded that sex differences in methylation are not the result of the immediate early actions of testosterone on the brain. Rather, the neural molecular patterns found in adults are conditioned by early hormonal exposures, the effects of which might emerge over a period of time. Gene Ontology analysis on the set of genes whose methylation was altered by testosterone revealed a significant enrichment of genes belonging to signaling components associated with dopamine modulation as well as movement disorders that display a male-bias. These data are consistent with striatum's role in regulation of movement.In addition to assessing the contribution of hormones to brain sexual differentiation, I also investigated the impact of sex chromosomes on sex differences in brain and behavior. To test for sex chromosome effects, I used the four core genotypes mouse model and found sex differences in expression of a subset of striatal genes caused by XX vs. XY differences in mice with the same gonadal type. Moreover, comparison of animals with different numbers of sex chromosomes in a novel mouse model of Klinefelter Syndrome (KS), the Sex Chromosome Trisomy Model, indicated that presence of an additional X chromosome and/or its interaction with the Y in XXY male mice can contribute to some of the behavioral and molecular phenotypes observed in KS. Interestingly, analysis of striatal transcriptome in KS mice revealed a feminized molecular signature in the brain of KS male mice. Such information is crucial knowledge in elucidating not only the pathophysiology of KS, but also the origin of sex differences in brain and behavior. Altogether, my work demonstrates the significance of genetics and epigenetics in the process of brain development as it relates to sex. The results presented in this dissertation suggest that (1) the sex chromosomes carry genes that could influence brain function and behavior; and (2) the long lasting effects of steroid hormones on the brain could be mediated by epigenetic mechanisms such as DNA methylation

Improved empirical and numerical predictive modelling of potential tailings dam breaches and their downstream impacts

Tailings dams are a fundamental component of mining infrastructure as they retain mine tailings, a complex material composed of finely ground rock, water and process effluent. Tailings dam breaches (TDBs) can cause catastrophic tailings flows that travel fast, cover large areas and cause widespread inundation. The ability to understand and predict the motion of tailings flows is a crucial step in protecting people, infrastructure and the environment. This thesis aims to improve predictive empirical and numerical models of potential tailings dam breaches and their downstream impacts to help practitioners develop more reliable inundation maps, dam classifications and emergency response and preparedness plans. To do so, a new tailings flow runout classification system was first developed. A comprehensive database of 33 TDBs was then compiled, and a new volume vs. inundation area relationship was developed for tailings flow runout prediction. Comparisons with similar relationships developed for other types of mass movements indicated that tailings flows are, on average, less mobile than lahars but more mobile than non-volcanic debris flows, rock avalanches, and waste dump failures. The adaptability of four numerical models to tailings flow runout modelling was also explored by conducting back-analyses of two well-described historical TDBs through a benchmarking exercise. The results showed that all four models are capable of reproducing the bulk characteristics of the real events. However, the study also highlighted challenges in the selection of appropriate model input parameter values and the need to develop better guidance on the use of these types of models for tailings flow runout prediction. To address these challenges through improved understanding of numerical model uncertainties and sensitivities, the First-Order Second-Moment (FOSM) methodology was applied to a sub-database of 11 back-analyzed historical tailings flows using the HEC-RAS numerical model. The results showed that the total released volume is among the top contributors to the sensitivity of modelled inundation area and maximum flow depth, while surface roughness is among the top contributors to the sensitivity of modelled maximum flow velocity and flow front arrival time. The FOSM methodology was also used to demonstrate a probabilistic approach to model-based tailings flow runout prediction.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofGraduat