Assessing Variability in Microstructural Influence on Fatigue Crack Growth Behavior

The effect of microstructural variability has long been recognized as a major contributing factor in the scatter of published fatigue data. It is also acknowledged that these effects are generally more prevalent for short cracks and in the threshold region. A number of models exist to explain individual microstructural effects such as grain boundary influence, grain cluster, average grain size, porosity etc. It is the aim of the Aeronautics and Astronautics Fatigue Lab to develop an encompassing model that accurately predicts these effects. In order to develop this model a range of material data will be required to inform and validate the model simulation. It is the aim of this thesis to develop the methods required to generate suitable fatigue crack data and also image the crack propagation and strain fields. The methodology from ASTM E647 was used for the determination of crack growth data with the notable exception of the use of compression pre-cracking and relevant crack growth models for the ESE(T) specimen. Compression pre-cracking methods have been utilised as data have shown that standard pre-cracking methods may affect crack growth rate data and the determination of threshold values. High and low load ratio tests were conducted with closure accounted for, allowing for accurate determination of the fatigue crack growth threshold. High resolution DIC imagery was captured for a range of loads over a range of crack lengths and enabled the visualization of material strain fields. The imagery also allowed correlation between fatigue crack growth variability, closure data and the tortuosity of the crack surface

Palladium catalysis for natural product synthesis

This thesis details investigations towards the total synthesis of the naturally occurring alkaloid hodgkinsine, utilising palladium catalysis to achieve desymmetrisation of a meso-chimonanthine derivative. Initially, a Suzuki cross-coupling approach was envisaged. Meso-chimonanthine is functionalised as its C-7 bisiodide derivative by directed ortho-lithiation. Suitable electrophiles are screened for the successful preparation of additional bisbromide and bistriflate derivatives to broaden the scope of the cross-coupling. The synthesis of a suitable indole-3-boronic ester coupling partner is also achieved. Investigations into the post-Suzuki coupling elaboration of the indole moiety were conducted with model substrates to assess the viability of a proposed alkylation-cyclisation procedure. C-3 alkylation of various N-protected C-3 phenylindole derivatives was unsuccessful when employing aziridines, sulfamidites and sulfamidates as electrophilic two carbon fragments. Therefore a second generation boronic ester with latent enolate functionality for increased nucleophilicity was prepared in six high yielding steps from oxindole, via trapping 3-bromo-N-BOC-oxindole as the TIPS enol ether and subsequent C-3 palladium catalysed borylation. The Suzuki coupling of the new boronic ester with meso-chimonanthine derivatives was shown to be unsuccessful in a broad range of anhydrous and aqueous solvent systems. Palladium catalysts, ligands, bases and measures to reduce steric interactions were all screened in an attempt to achieve coupling. Subsequently the palladium catalysed arylation of N-protected oxindole enolates is developed; aryl bromides, chlorides and triflates are all suitable coupling partners, whilst a broad range of ortho, meta and para functionalised arenes are well tolerated providing C-3 aryl oxindoles in high yield. Extension of this methodology to a C-7 bisbromo meso-chimonanthine substrate was successful, furnishing the desymmetrised product under racemic conditions in 45% yield with the dicoupled product also observed in 20% yield.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Genome Editing and Induced Pluripotent Stem Cell Technologies for Personalized Study of Cardiovascular Diseases

PURPOSE OF REVIEW: The goal of this review is to highlight the potential of induced pluripotent stem cell (iPSC)-based modeling as a tool for studying human cardiovascular diseases. We present some of the current cardiovascular disease models utilizing genome editing and patient-derived iPSCs. RECENT FINDINGS: The incorporation of genome-editing and iPSC technologies provides an innovative research platform, providing novel insight into human cardiovascular disease at molecular, cellular, and functional level. In addition, genome editing in diseased iPSC lines holds potential for personalized regenerative therapies. The study of human cardiovascular disease has been revolutionized by cellular reprogramming and genome editing discoveries. These exceptional technologies provide an opportunity to generate human cell cardiovascular disease models and enable therapeutic strategy development in a dish. We anticipate these technologies to improve our understanding of cardiovascular disease pathophysiology leading to optimal treatment for heart diseases in the future

Rectal Microbiome Composition Correlates with Humoral Immunity to HIV-1 in Vaccinated Rhesus Macaques.

The microbiome is an integral and dynamic component of the host and is emerging as a critical determinant of immune responses; however, its influence on vaccine immunogenicity is largely not well understood. Here, we examined the pivotal relationship between the mucosal microbiome and vaccine-induced immune responses by assessing longitudinal changes in vaginal and rectal microbiome profiles after intradermal immunization with a human immunodeficiency virus type 1 (HIV-1) DNA vaccine in adult rhesus macaques that received two prior DNA primes. We report that both vaginal and rectal microbiomes were dominated by Firmicutes but were composed of distinct genera, denoting microbiome specialization across mucosal tissues. Following immunization, the vaginal microbiome was resilient, except for a transient decrease in Streptococcus In contrast, the rectal microbiome was far more responsive to vaccination, exhibiting an increase in the ratio of Firmicutes to Bacteroidetes Within Bacteroidetes, multiple genera were significantly decreased, including Prevotella, Alloprevotella, Bacteroides, Acetobacteroides, Falsiporphyromonas, and Anaerocella. Decreased abundance of Prevotella correlated with induction of gut-homing α4β7 + effector CD4 T cells. Prevotella abundance also negatively correlated with rectal HIV-1 specific IgG levels. While rectal Lactobacillus was unaltered following DNA vaccination, baseline Lactobacillus abundance showed strong associations with higher rectal HIV-1 gp140 IgA induced following a protein boost. Similarly, the abundance of Clostridium in cluster IV was associated with higher rectal HIV-1 gp140 IgG responses. Collectively, these data reveal that the temporal stability of bacterial communities following DNA immunization is site dependent and highlight the importance of host-microbiome interactions in shaping HIV-1 vaccine responses. Our findings have significant implications for microbial manipulation as a strategy to enhance HIV vaccine-induced mucosal immunity.IMPORTANCE There is considerable effort directed toward evaluating HIV-1 vaccine platforms to select the most promising candidates for enhancing mucosal HIV-1 antibody. The most successful thus far, the RV144 trial provided partial protection due to waning HIV-1 antibody titers. In order to develop an effective HIV vaccine, it may therefore be important to understand how biological factors, such as the microbiome, modulate host immune responses. Furthermore, as intestinal microbiota antigens may generate antibodies cross-reactive to the HIV-1 envelope glycoprotein, understanding the relationship between gut microbiota composition and HIV-1 envelope antibody responses after vaccination is important. Here, we demonstrate for the first time in rhesus macaques that the rectal microbiome composition can influence HIV-1 vaccine immunogenicity, and we report temporal changes in the mucosal microbiome profile following HIV-1 vaccination. Our results could inform findings from the HIV Vaccine Trials Network (HVTN) vaccine studies and contribute to an understanding of how the microbiome influences HIV-1 antibody responses

Single-Cell RNA-seq Reveals Profound Alterations in Mechanosensitive Dorsal Root Ganglion Neurons with Vitamin E Deficiency.

Ninety percent of Americans consume less than the estimated average requirements of dietary vitamin E (vitE). Severe vitE deficiency due to genetic mutations in the tocopherol transfer protein (TTPA) in humans results in ataxia with vitE deficiency (AVED), with proprioceptive deficits and somatosensory degeneration arising from dorsal root ganglia neurons (DRGNs). Single-cell RNA-sequencing of DRGNs was performed in Ttpa-/- mice, an established model of AVED. In stark contrast to expected changes in proprioceptive neurons, Ttpa-/- DRGNs showed marked upregulation of voltage-gated Ca2+ and K+ channels in mechanosensitive, tyrosine-hydroxylase positive (TH+) DRGNs. The ensuing significant conductance changes resulted in reduced excitability in mechanosensitive Ttpa-/- DRGNs. A highly supplemented vitE diet (600 mg dl-α-tocopheryl acetate/kg diet) prevented the cellular and molecular alterations and improved mechanosensation. VitE deficiency profoundly alters the molecular signature and functional properties of mechanosensitive TH+ DRGN, representing an intriguing shift of the prevailing paradigm from proprioception to mechanical sensation

Investigating pediatric disorders with induced pluripotent stem cells

The study of disease pathophysiology has long relied on model systems, including animal models and cultured cells. In 2006, Shinya Yamanaka achieved a breakthrough by reprogramming somatic cells into induced pluripotent stem cells (iPSCs). This revolutionary discovery provided new opportunities for disease modeling and therapeutic intervention. With established protocols, investigators can generate iPSC lines from patient blood, urine, and tissue samples. These iPSCs retain ability to differentiate into every human cell type. Advances in differentiation and organogenesis move cellular in vitro modeling to a multicellular model capable of recapitulating physiology and disease. Here, we discuss limitations of traditional animal and tissue culture models, as well as the application of iPSC models. We highlight various techniques, including reprogramming strategies, directed differentiation, tissue engineering, organoid developments, and genome editing. We extensively summarize current established iPSC disease models that utilize these techniques. Confluence of these technologies will advance our understanding of pediatric diseases and help usher in new personalized therapies for patients

Isolated displaced non-union of a triquetral body fracture: a case report

<p>Abstract</p> <p>Introduction</p> <p>Fractures of the body of the triquetral bone are the second most common carpal fractures, and these fractures can be missed on plain X-ray. Although non-union of triquetral body fractures is very rare, such cases are associated with considerable morbidity and reduction in functional activity.</p> <p>Case presentation</p> <p>We report the case of a 29-year-old Caucasian British man who sustained an isolated displaced triquetral body fracture that resulted in non-union, who was treated surgically. We describe an original operative management for this debilitating injury. An open reduction and internal fixation using double headed compression screws was performed, without bone grafting, and with early immobilization of the wrist.</p> <p>Conclusions</p> <p>We propose this novel approach and advocate early clinical suspicion of triquetral body fractures in patients with a history of fall on an outstretched hand and ulnar sided wrist pain. We recommend evaluation using computed tomography or magnetic resonance imaging scanning.</p

Codevelopment Between Key Personality Traits and Alcohol Use Disorder From Adolescence Through Young Adulthood

ObjectivePersonality traits related to negative emotionality and low constraint are strong correlates of alcohol use disorder (AUD), but few studies have evaluated the prospective interplay between these traits and AUD symptoms from adolescence to young adulthood.MethodThe Minnesota Twin Family Study (N = 2,769) was used to examine the developmental interplay between AUD symptoms and three personality measures of constraint, negative emotionality, and aggressive undercontrol from ages 17 to 29.ResultsResults from random‐intercept, cross‐lagged panel models showed that low constraint and aggressive undercontrol predicted subsequent rank‐order increases in AUD symptoms from ages 17 to 24. AUD symptoms did not predict rank‐order change in these traits from ages 17 to 24. There was support for both cross‐effects from ages 24 to 29. Biometric analysis of the twin data showed genetic influences accounted for most of the phenotypic correlations over time.ConclusionResults are consistent with the notion that personality traits related to low constraint and aggressive undercontrol are important vulnerability/predisposition factors for the development of early adult AUD. In later young adulthood, there is more evidence for the simultaneous codevelopment of personality and AUD. Implications are addressed with attention to personality‐based risk assessments and targeted AUD prevention approaches.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142935/1/jopy12311.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142935/2/jopy12311_am.pd

Hypoplastic Left Heart Syndrome Sequencing Reveals a Novel NOTCH1 Mutation in a Family with Single Ventricle Defects

Hypoplastic left heart syndrome (HLHS) has been associated with germline mutations in 12 candidate genes and a recurrent somatic mutation in HAND1 gene. Using targeted and whole exome sequencing (WES) of heart tissue samples from HLHS patients, we sought to estimate the prevalence of somatic and germline mutations associated with HLHS. We performed Sanger sequencing of the HAND1 gene on 14 ventricular (9 LV and 5 RV) samples obtained from HLHS patients, and WES of 4 LV, 2 aortic, and 4 matched PBMC samples, analyzing for sequence discrepancy. We also screened for mutations in the 12 candidate genes implicated in HLHS. We found no somatic mutations in our HLHS cohort. However, we detected a novel germline frameshift/stop-gain mutation in NOTCH1 in a HLHS patient with a family history of both HLHS and hypoplastic right heart syndrome (HRHS). Our study, involving one of the first familial cases of single ventricle defects linked to a specific mutation, strengthens the association of NOTCH1 mutations with HLHS and suggests that the two morphologically distinct single ventricle conditions, HLHS and HRHS, may share a common molecular and cellular etiology. Finally, somatic mutations in the LV are an unlikely contributor to HLHS

Using reference-free compressed data structures to analyze sequencing reads from thousands of human genomes.

We are rapidly approaching the point where we have sequenced millions of human genomes. There is a pressing need for new data structures to store raw sequencing data and efficient algorithms for population scale analysis. Current reference-based data formats do not fully exploit the redundancy in population sequencing nor take advantage of shared genetic variation. In recent years, the Burrows-Wheeler transform (BWT) and FM-index have been widely employed as a full-text searchable index for read alignment and de novo assembly. We introduce the concept of a population BWT and use it to store and index the sequencing reads of 2705 samples from the 1000 Genomes Project. A key feature is that, as more genomes are added, identical read sequences are increasingly observed, and compression becomes more efficient. We assess the support in the 1000 Genomes read data for every base position of two human reference assembly versions, identifying that 3.2 Mbp with population support was lost in the transition from GRCh37 with 13.7 Mbp added to GRCh38. We show that the vast majority of variant alleles can be uniquely described by overlapping 31-mers and show how rapid and accurate SNP and indel genotyping can be carried out across the genomes in the population BWT. We use the population BWT to carry out nonreference queries to search for the presence of all known viral genomes and discover human T-lymphotropic virus 1 integrations in six samples in a recognized epidemiological distribution