Background: Due to its continuous exposure to food antigens and microbes, the gastrointestinal tract (GIT) is in a constant state of low level immune activation and contains an abundance of activated CCR5+CD4+ T lymphocytes, the primary target HIV-1. As a result, the GIT is a site of intense viral replication and severe CD4+ T cell depletion, a process that begins during primary HIV-1 infection and continues at a reduced rate during chronic infection in association with increased production of pro-inflammatory cytokines, a breakdown in the epithelial barrier, microbial translocation, systemic immune activation and the continued recruitment and infection of new target cells. AntiRetroviral Therapy (ART) is only partially effective in reversing these pathogenic changes. Despite the importance of the GIT in HIV-1 pathogenesis, and as a reservoir of persistent virus during ART, little is known about the diversity of HIV-1 in the GIT, or how different tissues in the GIT respond to ART. Objectives: Primary objectives of this thesis were to: 1) characterize the diversity of HIV-1 RNA variants in different parts of the GIT; 2) determine whether there is compartmentalized evolution of HIV-1 RNA variants in the GIT and whether these variants are likely to have different biological properties; 3) investigate the impact of ART on immune restoration in the GIT. Methods: A prospective study of the duodenum, jejunum, ileum and colon of African AIDS patients with chronic diarrhea and/or weight loss, sampled before and during 6 months of ART. RNA extracted from gut biopsies was reverse transcribed and PCR amplified. Env and gag PCR fragments were cloned, sequenced and subjected to extensive phylogenetic analysis; pol PCR fragments were analyzed for drug resistance. CD4+, CD8+ and CD38+CD8+ T cells levels in biopsies collected at baseline (duodenum, jejunum, ileum and colon) and after 3 (duodenum) and 6 (duodenum and colon) months of ART were quantified by flow cytometry and immunohistochemistry, plasma and tissue VL by the Nuclisens assay. Results: Viral diversity varied in different regions of the GIT with env HIV-1 RNA variants being significantly more diverse than gag variants. Gag HIV-1 RNA variants were widely dispersed among all tissue compartments. Some env variants formed tight monophyletic clusters of closely related viral quasispecies, especially in the colon, a finding that is suggestive of compartmentalized viral replication and adaptive evolution. CD4+ T cell and VL levels were significantly lower, while CD8+ including activated CD38+CD8+ T cell levels were higher in the duodenum and jejunum versus the colon. After 6 months of ART, a significant but incomplete recovery of CD4+ T cells was observed in the colon but not in the duodenum. Failed restoration of CD4+ T cells in the duodenum was associated with non-specific enteritis and CD8+ T cell activation. Conclusions: These results advance our understanding of the GIT as a host-pathogen interface by providing new insights into the diversity, evolution and dissemination of HIV-1 variants in the GIT. Strategies aimed at decreasing immune activation, especially in the small intestine, may be highly beneficial in enhancing the therapeutic efficacy of ART. / Thesis (PhD)--University of Pretoria, 2014. / lk2014 / Immunology / PhD / Unrestricted

The stomach is a digestive organ in the gastrointestinal tract that regulates food intake and paces digestion of nutrients and fluids. The emptying and motility patterns of the stomach are crucial rate-determining processes in maintaining energy homeostasis in the body. Dysregulation of gastric functions often leads to distressing conditions such as gastroesophageal reflux diseases, functional dyspepsia, gastroparesis and obesity. Gastric disorders affect more than 60 million people in the US, producing significant medical and economic burden. These diseases are often chronic and greatly compromise quality of life. As the causes of these diseases remain largely unknown, effects of current pharmacological, dietary, or surgical treatments are often dismal. In this regard, neuromodulation of peripheral nerves emerges as a promising electroceutical therapy for remedying gastric disorders. However, therapeutic effects were shown to be modest, largely due to the inability to validate or calibrate the efficacy and stability of neuromodulation methods with appropriate physiological readouts. To address these problems, here I developed a non-invasive, repeatable online high-resolution magnetic resonance imaging protocol, empowered with advanced image processing algorithms, to track gastric emptying, antral motility, pyloric motility, intestinal filling and absorption in a rat model. The protocol can be used to guide tuning and optimization of stimulation parameters of neuromodulation without perturbing ongoing and spontaneous physiology. The proposed technology and findings are expected to pave the way for the use of gastric MRI to evaluate the efficacy of therapeutics in treating gastric disorders under both preclinical and clinical settings.

Opioid-induced constipation (OIC) is one of the major adverse effects of opioid analgesics used by millions of patients each year. While progress has been made, there remains a significant unmet medical need in the treatment of OIC. Major gaps remain in our understanding of the role of the gastrointestinal tract and central nervous system (CNS) in precipitating OIC. For the last four decades, numerous investigations to study the sites of action of opioid analgesics have utilized peripherally acting mu-opioid receptor antagonists (PAMORAs), which have been incorrectly believed to have limited penetration across the blood-brain barrier (BBB). Several preclinical and clinical reports indicate that significant amounts of PAMORAs penetrate the BBB quite readily. As a result, the usage of current PAMORAs have resulted in misunderstandings of the role of the CNS and gastrointestinal tract in causing side effects such as opioid-induced constipation (OIC). We have developed a transthyretin-based novel drug delivery approach for restricting the passage of small molecules across the BBB. Our approach involves endowing the opioid agonist/antagonist with the selective transthyretin ligand, AG10. The newly synthesized naloxone- and oxycodone-based conjugates have demonstrated superior peripheral selectivity, improved pharmacokinetics, and efficacy in rats compared to other clinically used PAMORAs. Here we present chemical synthesis, in vitro binding and stability studies, as well as pharmacokinetic and pharmacodynamic evaluations of the AG10-opioid conjugates in rats. Our AG10-based PAMORA allowed us to obtain new insights into the important role of mu-opioid receptors in the central nervous system (CNS) in causing constipation. Additionally, our results demonstrate for the first time that synergy between mu-opioid receptors in the central nervous system and the gastrointestinal tract is crucial to the understanding of OIC and the development of effective treatment regimens. These findings contradict prior ideas that OIC was caused by a mechanism that involves primarily the gastrointestinal mu-opioid receptors. Moreover, we confirmed our findings by a AG10-oxycodone conjugate, a peripherally restricted opioid agonist. This molecule demonstrated the predominant role of CNS in OIC precipitation. The newly synthesized AG10-opioid conjugates represent a novel class of pharmacological probes that will aid in our understanding of OIC and other undesirable adverse effects of opioids. In addition, these conjugates have been evaluated for their potential therapeutic value in the preclinical studies. Collectively our approach to limit the BBB penetration of opioids will contribute to develop safer and more effective opioid medications.

Diabetes has caused many deaths worldwide but can be combated at least partially by diet and physical activity. The gut microbiome shows correlation with both type 1 and type 2 diabetes, has modulatory effects on the immune system and implicates brain functions through the gut-brain axis, in part by microbial metabolites. Diet has long been known to impact the microbiome but exercise has gained interest within the last decade, with studies mostly done on rodents and athletes with somewhat positive results on its modulation of the microbiome. This literature study aims to evaluate whether exercise can influence the microbiome for healthy, prediabetic, and diabetic cohorts and what this might mean for host health. The database PubMed was searched for articles in January 2021 and inclusion criteria yielded 7 articles for review. These differed in methods, cohorts, and exercise interventions, and therefore cannot grant any strong evidence but indicate along with previous research that exercise affects the microbiome, with slight differences in responses depending on the individual’s current state and exercising methods. / Diabetes har orsakat många dödsfall världen över men kan bekämpas åtminstone delvis med hjälp av diet och fysisk aktivitet. Tarmens mikrobiom har visats korrelera med både typ 1 och typ 2 diabetes, har reglerande effekter på immunsystemet och inverkar på hjärnfunktioner genom tarm-hjärna-axeln, delvis via metaboliter från mikroberna. Det har länge varit känt att mat kan påverka mikrobiomet, men träning har också väckt intresse över det senaste årtiondet med studier som fokuserat mest på möss och atleter med någorlunda positiva resultat för dess förändring av mikrobiomet. Denna litteraturstudie syftar till att undersöka om träning kan ha effekt på mikrobiomet hos såväl friska människor som prediabetiker och diabetiker, och vad detta kan betyda för hälsan. En litteratursökning gjordes i databasen PubMed i januari 2021 som efter sortering enligt inkluderande kriterier gav 7 artiklar för granskning. Dessa använde olika metoder, undersökta grupper och träningsupplägg, vilket försvårar jämförelser men indikerar i linje med tidigare forskning att träning påverkar mikrobiomet, med en del skillnader i resultat beroende på individens status och träningsupplägg.

In cancer, aberrant activation of developmental signaling pathways such as the Hippo Pathway has been shown to drive proliferation and invasion of cancer cells. Therefore, understanding the normal function of the Hippo Pathway during embryonic development can provide critical insight into how aberrant activity contributes to tumorigenesis. This dissertation explores the role of the Hippo Pathway members YAP and TAZ in gastrointestinal (GI) development and tumorigenesis. I use mouse genetics to systematically dissect the roles of YAP/TAZ in the endoderm-derived gastrointestinal epithelia and mesoderm-derived gastrointestinal mesenchyme during mammalian development. In the GI epithelium, I demonstrate that YAP/TAZ are dispensable for development and homeostasis. However, YAP/TAZ are required for Wnt pathway-driven tumorigenesis. I find that YAP/TAZ are direct transcriptional targets of Wnt/TCF4 signaling. In the GI mesenchyme, I describe a previously unknown requirement for YAP/TAZ activity during mammalian GI development. YAP/TAZ are involved in normal GI mesenchymal differentiation and function as transcriptional co-repressors in a progenitor cell population. In this way, YAP/TAZ act as molecular gatekeepers prior to Hedgehog-mediated differentiation into smooth muscle cells. This work unveils a previously unknown requirement for Hippo pathway signaling in the mammalian GI tract and a novel mechanism wherein YAP/TAZ function as transcriptional co-repressors to maintain a mesenchymal progenitor cell population.

Indiana University-Purdue University Indianapolis (IUPUI) / Glucagon-like peptide 1 (GLP-1) receptor agonists are a class of incretin based therapeutics which aid in blood glucose management in Type II diabetes mellitus (T2DM). Recent studies have demonstrated direct cardiovascular benefits conferred by these agents including protection in ischemia and heart failure. Despite these observations, human clinical trials fail to support improvements in cardiovascular outcomes independent of glucose lowering effects in the T2DM populations. Prior data from our lab demonstrate that obesity impairs GLP-1 associated increases in myocardial glucose uptake. However, the reasons for this impairment/resistance to cardiac effects of GLP-1 in the setting of obesity remain ill defined. This investigation tested the hypothesis that underlying differences in the cardiac proteome and microRNA (miR) transcriptome could contribute to distinct cardiac responses to ischemia and activation of GLP-1 signaling in the setting of obesity. To identify whether obesity modulated cardiac functional responses to GLP 1 related drugs, we first examined the effects of obesity on cardiac function, miR transcriptome, and proteome in response to short duration ischemia-reperfusion (I/R). We observed divergent physiologic responses (e.g. increased diastolic volume and systolic pressure in lean, decreased diastolic volumes in obese) to regional I/R in obese vs lean hearts that were associated with significant molecular changes as detected by protein mass spectrometry and miR microarray. Molecular changes were related to myocardial calcium handling (SERCA2a, histidine-rich Ca2+ binding protein), myocardial structure and function (titin), and miRs relating to cardiac metabolism, hypertrophy, and cell death, including miR-15, miR-30, miR-199a, miR-214. Importantly, these effects were modified differently by GLP-1 agonism in lean vs obese swine. Additional studies investigated the functional effects of 30 days of treatment with the GLP-1 analogue liraglutide on a model of slowly-developing, unrelieved coronary ischemia. Liraglutide failed to reduce infarct size or collagen deposition. However, analysis of left ventricular pressure-volume relationships support that liraglutide improved diastolic relaxation/filling, load-dependent indices of cardiac function, and cardiac efficiency in response to sympathetic stimulation in obese swine. Taken together, these findings support that miR and proteomic differences underlie distinct changes in functional cardiac responses to I/R and pharmacologic activation of GLP-1 signaling in the setting of obesity.

The relative risk of major gastrointestinal bleeding (GIB) among different direct oral anticoagulants (DOACs) is debatable. Randomized controlled trials (RCTs) comparing DOACs with each other are lacking. We performed network meta-analysis to assess whether the risk of major GIB differs based on type and dose of DOAC. Literature search of PubMed, EMBASE and Cochrane databases from inception to August 2019, limited to English publications, was conducted to identify RCTs comparing DOACs with warfarin or enoxaparin for any indication. Primary outcome of interest was major GIB risk. We used frequentist network meta-analysis through the random-effects model to compare DOACs with each other and DOACs by dose to isolate the impact on major GIB. Twenty-eight RCTs, including 139 587 patients receiving six anticoagulants, were selected. The risk of major GIB for DOACs was equal to warfarin. Comparison of DOACs with each other did not show risk differences. After accounting for dose, rivaroxaban 20 mg, dabigatran 300 mg and edoxaban 60 mg daily had 47, 40 and 22% higher rates of major GIB versus warfarin, respectively. Apixaban 5 mg twice daily had lower major GIB compared to dabigatran 300 mg (OR, 0.63; 95% CI, 0.44-0.88) and rivaroxaban 20 mg (OR, 0.60; 95% CI, 0.43-0.83) daily. Heterogeneity was low, and the model was consistent without publication bias (Egger's test: P = 0.079). All RCTs were high-quality with low risk of bias. DOACs at standard dose, except apixaban, had a higher risk of major GIB compared to warfarin. Apixaban had a lower rate of major GIB compared to dabigatran and rivaroxaban.

No description available.

Background The detrimental impact of malnutrition and cachexia in cancer patients subjected to surgical resection is well established. However, how systemic and local metabolic alterations in cancer patients impact the serum metabolite signature, thereby leading to cancer-specific differences, is poorly defined. In order to implement metabolomics as a potential tool in clinical diagnostics and disease follow-up, targeted metabolite profiling based on quantitative measurements is essential. We hypothesized that the quantitative metabolic profile assessed by 1H nuclear magnetic resonance (NMR) spectroscopy can be used to identify cancer-induced catabolism and potentially distinguish between specific tumour entities. Importantly, to prove tumour dependency and assess metabolic normalization, we additionally analysed the metabolome of patients' sera longitudinally post-surgery in order to assess metabolic normalization. Methods Forty two metabolites in sera of patients with tumour entities known to cause malnutrition and cachexia, namely, upper gastrointestinal cancer and pancreatic cancer, as well as sera of healthy controls, were quantified by 1H NMR spectroscopy. Results Comparing serum metabolites of patients with gastrointestinal cancer with healthy controls and pancreatic cancer patients, we identified at least 15 significantly changed metabolites in each comparison. Principal component and pathway analysis tools showed a catabolic signature in preoperative upper gastrointestinal cancer patients. The most specifically upregulated metabolite group in gastrointestinal cancer patients was ketone bodies (3-hydroxybutyrate, P < 0.0001; acetoacetate, P < 0.0001; acetone, P < 0.0001; false discovery rate [FDR] adjusted). Increased glycerol levels (P < 0.0001), increased concentration of the ketogenic amino acid lysine (P = 0.03) and a significant correlation of 3-hydroxybutyrate levels with branched-chained amino acids (leucine, P = 0.02; isoleucine, P = 0.04 [FDR adjusted]) suggested that ketone body synthesis was driven by lipolysis and amino acid breakdown. Interestingly, the catabolic signature was independent of the body mass index, clinically assessed malnutrition using the nutritional risk screening score, and systemic inflammation assessed by CRP and leukocyte count. Longitudinal measurements and principal component analyses revealed a quick normalization of key metabolic alterations seven days post-surgery, including ketosis. Conclusions Together, the quantitative metabolic profile obtained by 1H NMR spectroscopy identified a tumour-induced catabolic signature specific to upper gastrointestinal cancer patients and enabled monitoring restoration of metabolic homeostasis after surgery. This approach was critical to identify the obtained metabolic profile as an upper gastrointestinal cancer-specific signature independent of malnutrition and inflammation.

No description available.