5,863 research outputs found
Management strategies and contributory factors for resistance exercise-induced muscle damage: an exploration of dietary protein, exercise load, and sex
The World Health Organisation recommends that resistance exercise be performed at least twice per week to benefit general health and wellbeing. However, resistance exercise is associated with acute muscle damage that potentially can dampen muscle adaptations promoted by chronic resistance training. The extent to which muscle is damaged by exercise is influenced by various factors, including age, training status, exercise type, and – notable to this thesis – sex. To this end, establishing sex-specific management strategies for exercise-induced muscle damage (EIMD) is important to optimise the benefits of exercise. Two EIMD management strategies were focussed on in this thesis: dietary protein supplementation and exercise load manipulation.
It was identified in this thesis that research into the impact both of protein supplementation and exercise load on EIMD heavily underrepresent female populations (chapters 3 and 5), despite well-documented sex differences in EIMD responses. Therefore, future research priority should be placed on bridging the sex data gap by conducting high-quality studies centralising around female-focussed and sex-comparative methodological designs.
Both peri-exercise protein supplementation and exercise load manipulation in favour of lighter loads were revealed to be effective management strategies for resistance EIMD in males through systematic and scoping review of the current literature (chapters 3 and 5, respectively). Due to a lack of data from females, it is only appropriate for these strategies to be recommended for males at present. To decipher whether protein supplementation and lower exercise loads are beneficial for managing EIMD in females, a randomised controlled trial (RCT) (chapter 4) and a protocol for an RCT (chapter 6) involving male and female participants are presented in this thesis.
The incorporation of ecologically-valid resistance exercise in the RCT in chapter 4 highlighted that even mild muscle damage is attenuated in females, reflected in diminished increases in post-exercise creatine kinase concentration and muscle soreness compared with males; however, the reason for this difference requires further investigation. This study, while supporting sex differences, contrasted previous studies, as neither males nor females experienced an attenuation of EIMD during milk protein supplementation. This difference likely owed to the lower severity of muscle damage induced in the current study relative to previous studies, and accordingly, future research should seek to discover alternative management strategies for mild EIMD. A protocol for an RCT examining the impact of exercise load on EIMD in untrained males and females is described in Chapter 6 of this thesis and may be used as guidance for researchers developing similar, sex-comparative studies. It was hypothesised that females will experience attenuated muscle damage relative to males and low-load exercise will induce less muscle damage than high-load exercise in both sexes.
A lack of methodological consistency among EIMD studies was a recurring finding throughout this thesis, which posed an issue when attempting to compare between-study outcomes and reach a consensus. Achieving greater uniformity in study designs by adopting comparable methods relating to EIMD markers and time-points of assessment would help improve understanding of the factors influencing the magnitude of EIMD and effective management strategies. While there are limitations with several EIMD markers – for example the variability of biomarkers and subjectivity of perceptual assessments – once the optimal markers are determined, these should be consistently used moving forward.
Overall, this thesis has contributed to the current body of knowledge by demonstrating that milk protein ingestion is not an effective management strategy for muscle damage following ecologically-valid resistance exercise; therefore, alternative strategies to mitigate mild muscle damage should be investigated. Further, this work supported previous reports of sex differences in EIMD and indicated that the attenuation of EIMD in females relative to males was not attributed to sex differences in body composition; thus, the aetiology of such differences necessitates further exploration by means of high-quality sex comparative research. Finally, this thesis reached the consensus recommendation that lower exercise loads can be utilised to reduce muscle damage in males; nonetheless, supporting evidence for the application of this recommendation to females is required
Homeostasis in Immunity-Related Pupal Tissues of the Malaria Mosquito Anopheles gambiae and its regulation by the NF-kappaB-like Factor Rel2
Die Haut ist eine oft übersehene Komponente des angeborenen Immunsystems der Mücken. Die Haut der Mücke bildet eine physische Barriere, die die mikrobielle Homöostase aufrechterhält, das Eindringen von Toxinen wie Insektiziden verhindert und das Austrocknen verhindert. Die am meisten untersuchten Akteure des Immunsystems von Stechmücken sind das Fettgewebe und die Blutzellen, aber die Hauttalg-Fabriken, die Oenozyten, werden in Studien nur selten berücksichtigt.
Mückenpuppen haben aktiv funktionierende immunitätsbezogene Organe, einschließlich derjenigen, die Hautbarrieren produzieren. Ihre biologische Rolle in diesem Entwicklungsstadium ist kaum bekannt, aber der Übergang von der Puppen- zur Erwachsenenhaut und die Auffälligkeit der talgproduzierenden Zellen machen dieses Stadium zu einem vielversprechenden Entwicklungsstadium für die Untersuchung der Hautbildung.
Mit Hilfe der Transkriptomanalyse beschreiben wir die Rolle der Blutzellen bei der Entwicklung des chitinösen Teils der Insektenhaut, die Beteiligung des Fettkörpers an der Immunität und bestätigen die Rolle der talgproduzierenden Zellen im Lipidstoffwechsel. Darüber hinaus beschreiben wir talgsezernierende Zellen als einen bedeutenden Wirkungsort des NF-kappaB-ähnlichen IMD-Rel2-Pathway, in dem der Transkriptionsfaktor Rel2 die Retinoid-Homöostase reguliert. Schließlich bestätigen wir eine 100 Jahre alte Beobachtung, wonach sebumsezernierende Zellen der Stechmücke ihren Zellinhalt in einem Netzwerk von Vesikeln absondern. Wir beschreiben extrazelluläres Chromatin als Fracht in diesem Vesikelnetzwerk und sein antimikrobielles Potenzial.The skin is an often overlooked component of the mosquito's innate immune system. The mosquito skin provides a physical barrier that maintains microbial homeostasis, prevents the entry of toxins like insecticides, and avoids desiccation. The most studied players in the immune system of mosquitoes are the adipose tissue and blood cells, but studies rarely consider the skin sebum factories, oenocytes.
Mosquito pupae have actively functional immunity-related organs, including those producing skin barriers. Their biological roles at this developmental stage are poorly understood, but the pupae-to-adult metamorphic skin transition and the conspicuity of sebum-secreting cells make it a promising developmental stage to study skin formation.
We use transcriptomics to describe the role of blood cells in the development of the chitinous section of the insect skin, the involvement of the fat body in immunity, and confirm the lipid metabolism role of sebum-secreting cells. Furthermore, we describe sebum-secreting cells as a significant action site of the NF-kappaB-like IMD-Rel2 pathway where the transcription factor Rel2 regulates retinoid homeostasis. Finally, we confirm a 100-year-old observation of how mosquito sebum-secreting cells secrete their cellular contents in a network of vesicles. We describe extracellular chromatin as cargo inside this vesicle network and its antimicrobial potential
Multi-dimensional omics approaches to dissect natural immune control mechanisms associated with RNA virus infections
In recent decades, global health has been challenged by emerging and re-emerging
viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), human
immunodeficiency viruses (HIV-1), and Crimean–Congo hemorrhagic fever virus (CCHFV).
Studies have shown dysregulations in the host metabolic processes against SARS-CoV2
and HIV-1 infections, and the research on CCHFV infection is still in the infant stage. Hence,
understanding the host metabolic re-programming on the reaction level in infectious
disease has therapeutic importance. The thesis uses systems biology methods to
investigate the host metabolic alterations in response to SARS-CoV2, HIV-1, and CCHFV
infections.
The three distinct viruses induce distinct effects on human metabolism that,
nevertheless, show some commonalities. We have identified alterations in various
immune cell types in patients during the infections of the three viruses. Further,
differential expression analysis identified that COVID-19 causes disruptions in pathways
related to antiviral response and metabolism (fructose mannose metabolism, oxidative
phosphorylation (OXPHOS), and pentose phosphate pathway). Up-regulation of OXPHOS
and ROS pathways with most changes in OXPHOS complexes I, III, and IV were identified
in people living with HIV on treatment (PLWHART). The acute phase of CCHFV infection is
found to be linked with OXPHOS, glycolysis, N-glycan biosynthesis, and NOD-like receptor
signaling pathways. The dynamic nature of the metabolic process and adaptive immune
response in CCHFV-pathogenesis are also observed.
Further, we have identified different metabolic flux in reactions transporting TCA cycle
intermediates from the cytosol to mitochondria in COVID-19 patients. Genes such as
monocarboxylate transporter (SLC16A6) and nucleoside transporter (SLC29A1) and
metabolites such as α-ketoglutarate, succinate, and malate were found to be linked with
COVID-19 disease response. Metabolic reactions associated with amino acid,
carbohydrate, and energy metabolism pathways and various transporter reactions were
observed to be uniquely disrupted in PLWHART along with increased production of αketoglutarate (αKG) and ATP molecules. Changes in essential (leucine and threonine) and
non-essential (arginine, alanine, and glutamine) amino acid transport were found to be
caused by acute CCHFV infection. The altered flux of reactions involving TCA cycle
compounds such as pyruvate, isocitrate, and alpha-ketoglutarate was also observed in
CCHFV infection.
The research described in the thesis displayed dysregulations in similar metabolic
processes against the three viral Infections. But further downstream analysis unveiled
unique alterations in several metabolic reactions specific to each virus in the same
metabolic pathways showing the importance of increasing the resolution of knowledge
about host metabolism in infectious diseases
Specificity of the innate immune responses to different classes of non-tuberculous mycobacteria
Mycobacterium avium is the most common nontuberculous mycobacterium (NTM) species causing infectious disease. Here, we characterized a M. avium infection model in zebrafish larvae, and compared it to M. marinum infection, a model of tuberculosis. M. avium bacteria are efficiently phagocytosed and frequently induce granuloma-like structures in zebrafish larvae. Although macrophages can respond to both mycobacterial infections, their migration speed is faster in infections caused by M. marinum. Tlr2 is conservatively involved in most aspects of the defense against both mycobacterial infections. However, Tlr2 has a function in the migration speed of macrophages and neutrophils to infection sites with M. marinum that is not observed with M. avium. Using RNAseq analysis, we found a distinct transcriptome response in cytokine-cytokine receptor interaction for M. avium and M. marinum infection. In addition, we found differences in gene expression in metabolic pathways, phagosome formation, matrix remodeling, and apoptosis in response to these mycobacterial infections. In conclusion, we characterized a new M. avium infection model in zebrafish that can be further used in studying pathological mechanisms for NTM-caused diseases
Molecular mechanisms of nutrient sensing in the human and murine colon
Background: Nutrient-sensing, G-protein coupled receptors (GPCRs) expressed on enteroendocrine cells (EECs) bind and are activated by specific nutrients. Receptor binding leads to cell activation and release of specific hormones/peptides, such as peptide-YY (PYY), GLP-1 and serotonin, which regulate appetite and satiety (le Roux and Bloom, 2005), (Lund et al., 2018). Research is currently lacking on the cellular mechanisms of these processes in the human and murine colon. I therefore aimed to characterise the expression and release of GPCRs, hormones, peptides. Hypothesis: Altered nutrient receptors expression can alter cell activation and the release of hormones and peptides leading to reduced postprandial satiety. Methods: qPCR was used to assess the relative expression of nutrient GPCRs and hormone/peptides in human colonic tissue at the genetic level, and immunohistochemistry at the protein level. Murine tissue was used in Ussing chamber experiments to determine cellular activation in response to GPCR activation and then ELISAs used to determine the change in release of hormones/ peptides from these activated cells. Results: Expression studies revealed no difference in the mRNA expression of serotonin and PYY between BMI groups in humans. GPR40 mRNA was the only GPCR to be significantly altered, being increased in the sigmoid colon of individuals with BMI ≥25. Stimulation of murine tissue with a GPR40 agonist increased intracellular activation via ERK activation in serotonin-expressing cells, whilst a CaSR agonist decreased CaMKII activation in PYY-expressing cells. There was no observed change in cellular activation in other target GPCRs. Release of PYY or serotonin was not affected by stimulation or antagonism of GPCRs, or antagonism of the CaMKII pathway. Conclusion: BMI does not affect the mRNA or cell expression of the examined nutrient receptors (except GPR40), hormones or expression of enterochromaffin, L cells in our cohort of human colon samples. Obesity may alter other functions such as hormone release. GPCR agonists can alter the activation state of PYY- and serotonin-expressing L and EC cells in mice, with intracellular pathway activation being agonist- and GPCR-dependent
Evolution and Architecture of Epigenetic Regulation in the Genome
Epigenetic modifications are genomic alterations which regulate the expression and activity of genes by changing the structure of chromatin. These mechanisms of regulation expand the proportion of the genome that is functional well beyond the comparably rare instances of protein coding genes, which, in humans, only correspond to ~2% of the genome. The aim of this dissertation is to leverage advances in the genomic identification and annotation of epigenetic modifications to explore questions regarding the (1) role of DNA methylation in X chromosome regulation through comparative genomic analyses, (2) the organization and (3) evolution of enhancers identified from histone modifications.
In the second chapter of this thesis, we consider the role of DNA methylation in an iconic example of epigenetic regulation, namely the X chromosome inactivation (XCI). XCI is the process by which one of the two female X chromosomes is silenced to balance the expression of X-linked genes in male and female genomes and is functionally conserved in two branches of mammals (eutherians and marsupials). In eutherians, it is well established that DNA methylation plays a role in establishing XCI through the silencing of the lncRNA Xist on the active X chromosome as well as in the long-term maintenance of inactive X-linked genes. However, the role of DNA methylation in marsupials remains controversial. We utilize novel multi-tissue, sex-inclusive Whole Genome Bisulfite Sequencing (WGBS) coupled with improved genomic annotations to elucidate the role of DNA methylation in X chromosome regulation in a representative marsupial, the modern koala (Phascolarctos cinereus). Consequently, we clarify conserved and divergent roles of DNA methylation on the regulation of XCI in marsupials and eutherians.
In the following two chapters, we integrate multi “-omics” datasets including whole genome chromatin state maps and gene expression data from a diverse set of tissues to elucidate the organization and evolution of human enhancers, a hallmark of the (epi)genomic regulatory landscape. Enhancers are short, mostly non-coding DNA sequences that orchestrate the context- and developmental time-specific expression of associated genes. Enhancers are often studied as highly tissue-specific regulatory elements in what has been deemed a “paradigm of modularity.” However, contrary evidence, indicating that a subset of enhancers may be repurposed in multiple tissue and/or developmental contexts, is mounting. In this study, we characterize the previously unknown frequency and genomic characteristics of these highly “pleiotropic” enhancers. We further evaluate the organization of the larger gene-enhancer interaction network considering (1) the distribution of enhancer pleiotropy, (2) the variations in the number of enhancer-target gene links, and (3) the expression breadth of target genes.
Furthermore, we explore the evolution of human enhancer through genomic duplication events. Duplications are a canonical reservoir of the raw material needed for the evolution of novel functional elements in the genome and have been studied extensively with respect to genes. The selective processes governing the maintenance of duplicate genes are well characterized, and similar evolutionary mechanisms have been proposed for non-coding regulatory elements. However, whether duplication events affect enhancer evolution and maintenance is currently unknown. Through sequence homology analyses, we identify likely candidate duplicate enhancers in our large dataset to determine the frequency of duplicate enhancer retention in the human genome. Additionally, we determine the characteristics of duplicate enhancers contributing to their evolutionary maintenance. We demonstrate that duplication of enhancers has significant footprint on pleiotropic enhancers and that recently duplicated human enhancers exhibit signatures of accelerated evolution and specialized for immune related functions.
Together, these studies reveal previously unknown patterns of conservation and divergence of epigenetic regulatory mechanisms along two deep branches of mammals, as well as elucidate the molecular architecture and the impact of duplication on the genomic landscape of enhancer-gene regulation.Ph.D
2023 Summer Experience Program Abstracts
https://openworks.mdanderson.org/sumexp23/1130/thumbnail.jp
2023-2024 academic bulletin & course catalog
University of South Carolina Aiken publishes a catalog with information about the university, student life, undergraduate and graduate academic programs, and faculty and staff listings
Crystallographic fragment screening - improvement of workflow, tools and procedures, and application for the development of enzyme and protein-protein interaction modulators
One of the great societal challenges of today is the fight against diseases which reduce
life expectancy and lead to high economic losses. Both the understanding and the
addressing of these diseases need research activities at all levels. One aspect of this is
the discovery and development of tool compounds and drugs. Tool compounds support
disease research and the development of drugs. For about 20 years, the discovery of new
compounds has been attempted by screening small organic molecules by high-throughput
methods. More recently, X-ray crystallography has emerged as the most promising method
to conduct such screening. Crystallographic fragment-screening (CFS) generates binding
information as well as 3D-structural information of the target protein in complex with the
bound fragment. This doctoral research project is focused primarily on the optimization of
the crystallographic fragment screening workflow. Investigated were the requirements for
more successful screening campaigns with respect to the crystal system studied, the
fragment libraries, the handling of the crystalline samples, as well as the handling of the
data associated with a screening campaign. The improved CFS workflow was presented
as a detailed protocol and as an accompanying video to train future CFS users in a
streamlined and accessible way. Together, these improvements make CFS campaigns a
more high-throughput method, offering the ability to screen larger fragment libraries and
allowing higher numbers of campaigns performed per year. The protein targets throughout
the project were two enzymes and a spliceosomal protein-protein complex. The enzymes
comprised the aspartic protease Endothiapepsin and the SARS-Cov-2 main protease. The
protein-protein complex was the RNaseH-like domain of Prp8, a vital structural protein in
the spliceosome, together with its nuclear shuttling factor Aar2. By performing the CFS
campaigns against disease-relevant targets, the resulting fragment hits could be used
directly to develop tool compounds or drugs. The first steps of optimization of fragment
hits into higher affinity binders were also investigated for improvements. In summary, a
plethora of novel starting points for tool compound and drug development was identified
- …