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1
Solligård, Erik. "Gut luminal microdialysis." Doctoral thesis, Norwegian University of Science and Technology, Department of Circulation and Medical Imaging, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1878.
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Donaldson, Charles A. "Got a Gut Feeling: Truthiness, conspiracy and archives in contemporary culture." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/408101.
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This exegesis reports on research undertaken for the fulfilment of my Master of Visual Arts candidature at Griffith University. My research project takes the form of a practice led installation-based studio methodology. Through the fabrication of objects in the context of a visual arts practice that parodies archival systems, it aims to effect change in our contemporary understanding of “objective” truth by exploring the impact of truthiness (emotionally motivated belief, confirmed by gut feeling instead of facts) and embracing conspiracy culture. I argue that truthiness is widespread online as a sociopolitical tool and phenomenon. I contend the rise of mass information overload and image circulation online has propagated truthiness into every aspect of an increasingly online visual culture. I examine the rise of conspiracy as a mainstream visual language and discuss why and how individuals come to accept alternative accounts of history and explanations of the present. I assess the role of archival preservation in contemporary information dissemination, examining the influence of online systems upon how we store and access socio-political materials. I contend that archives can no longer be considered objective sites that merely and apolitically store/catalogue information. Rather, archives are subjective sites of interpretation and construction, produced and managed by many from diverse backgrounds—including artists. I discuss the methodology of genealogical research, suggesting that a multifaceted approach to historiography generates a new “effective” history, informed by multiple perspectives that aim to change interpretations of history and historiography. I identify a contextual correlation between the work of three practitioners— namely, Trevor Paglen’s conspiratorially bent research, Walid Raad’s fabricated archive and Christian Boltanski’s archival parodies. This correlation points to a congruity of research into the impact of truthiness, archival subjectivity, and mainstream conspiracy culture in contemporary art. Finally, I discuss two research outcomes and conclude whether the aims of the research project have been achieved.Thesis (Masters)
Master of Visual Arts (MVA)
Queensland College of Art
Arts, Education and Law
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Altera, Annalisa. "Gut-brain axis: the role of microbiota in gut and brain ageing." Doctoral thesis, Università di Siena, 2022. http://hdl.handle.net/11365/1209555.
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In the last decade there has been a growing interest in the reciprocal impact occurring between the gut and the brain and this is well conceptualized in the gut-brain axis notion. The gut-brain axis is the bidirectional communication route between the “little brain” (gut) and the “big brain” (brain). There are several factors that play an important role in this axis but it has become more and more evident that the gut bacteria represent a key component. This has led to the new concept of the microbiota-gut-brain axis, emphasizing the importance of the gut microbiota in this axis. The gut has evolved with bacteria in a symbiotic way and the human gut hosts about 1014 bacterial cells. Researches in the last years have highlighted the importance of the microbiota not only for gut functions but also for the central nervous system (CNS) development, physiology and pathology. However, there are different factors that influence the composition of the gut microbiota (mode of delivery, diet, stress and ageing). In particular, the composition of the gut microbiota changes with ageing: in the adults the majority of taxa are Bacteroidetes and Firmicutes while the elderly has a different composition of the gut microbiota. Some studies have reported a decrease in Bifidobacteria and an increase in Escherichia, Enterobacteriaceae and Clostridium difficile in the elderly. Interestingly, the centenarians apparently have no changes in gut microbiota in comparison to adult, further highlighting the importance of gut bacteria in longevity. Ageing is a physiological process related to the loss of function in different body systems and also associated with a decline in cognitive functions. It has become more and more evident that events taking place in the gut play a major role in the ageing process and in age-related diseases. Faecal microbial transplant (FMT) is a technique that consists in the transfer of gut microbiota from a donor to a recipient (usually via an oral gavage in rodents or colonoscopy in humans) and allows to establish a donor-like microbiota in the gastro-intestinal tract of the recipient. FMT is used to treat recurrent Clostridium difficile infections but there are studies trying to test this technique in the treatment of other pathologies such as irritable bowel syndrome, inflammatory bowel disease and constipation. It is also worth noticing that the
imbalance in the composition of the gut microbiota (dysbiosis) has been associated with a plethora of neurological disorders. In this context FMT is being investigated as a therapeutic option not only for treatment of gut disorders but also for diseases of the CNS. The present thesis illustrates a series of experiments by which we tested the impact of FMT from aged donor mice into young adult recipients. Controls were carried out operating FMT from young adult donor mice to age-matched recipients. Following transplantation, characterization of the microbiota and metabolomics profiles along with a series of cognitive and behavioural tests were carried out. Label-free quantitative proteomics was employed to evaluate protein expression in the hippocampus and gut after the transplant.
In addition, in the attempt to elucidate the mechanisms underlying microbiota-host interactions within the framework of the gut-brain axis, we worked on setting up a procedure to tracking down and visualize bacterial metabolites (such as peptides and lipids) that are thought to play a role acting as signaling molecules. To this end, we used copper-catalysed azide-alkyne cycloaddition (CuAAC) click chemistry, a biorthogonal reaction of widespread utility throughout medical chemistry and chemical biology. We sought to optimize click-based protocols to detect the production of lipids in gut-bacteria to track the metabolism of active bacterial cells. This technique use click chemistry to stain synthetic (e.g., noncanonical) precursors incorporated into bacterial cell biomass. After incorporation, the artificial molecules can be fluorescently detected via azide-alkyne reaction and visualized by confocal microscopy.
FMT from aged mice into adult recipients affected spatial learning and memory while we did not observe effects on locomotion and explorative behaviour. Alongside, there was an alteration in the expression of proteins related to synaptic plasticity and neurotransmission in the hippocampus which was not observed in controls. FMT from aged into young adult mice did not induce a significant increase in glial fibrillary acidic protein expression in hippocampal astrocytes suggesting the lack of an overt neuroinflammatory response. On the other hand, a significant increase in the expression of F4/80, a typical trait of the ageing brain, was observed in microglial cells resident in the fimbria. Gut permeability and levels of systemic and local (hippocampus, gut) cytokines were not affected. As regards click chemistry, we used
Bacteroides thetaiotaomicron grown in minimal medium supplemented with palmitic acid alkyne (PAA) and stained this molecule using an azide-containing fluorescent dye. After palmitic acid staining, co-culture experiments were performed to assess the transfer of this bacterial product to eukaryotic cell lines (CaCo2 and SK-N-SH cell lines). The successful transfer to host cells was confirmed by confocal microscopy. Results obtained in FMT experiments highlighted the importance of the gut microbiota on protein expression and functions of CNS. These results support the key role of microbiota in gut-brain axis and it would be of great importance to get more insight into the restoration of a young microbiota in the elderly to try to improve cognitive functions and the quality of life. Click chemistry experiments demonstrate that this technique could be employed to track molecules produced by gut bacteria to unveil their role in host-microbe interactions.
4
Kehler, Holger. "Dresden ist gut beraten." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-89645.
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Die seit 2009 wirkende Initiative „Lernen vor Ort “ des Bundesministeriums für Bildung und Forschung schafft gemeinsam mit einem Verbund deutscher Stiftungen für 40 Kreise und kreisfreie Städte Anreize, die Verantwortung in Bildungsfragen zu stärken und dafür ein datengestütztes Bildungsmanagement zu etablieren. Die Landeshauptstadt Dresden verfolgt mit dem Aufgreifen dieser Initiative das Ziel, „allen Dresdner Bürgern größere Chancen für eine bestmögliche Bildungs(lauf)bahn zu eröffnen“ (Oberbürgermeisterin Helma Orosz).
5
Le, Roux Carel Wynand. "Gut hormones and appetite." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/7840.
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McIntyre, Jan. "God in the gut." Online full text .pdf document, available to Fuller patrons only, 2003. http://www.tren.com.
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Yamashita, Toshifumi. "Anomalous U(1) GUT." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/145082.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第11314号
理博第2872号
新制||理||1429(附属図書館)
22957
UT51-2005-D65
京都大学大学院理学研究科物理学･宇宙物理学専攻
(主査)教授 川合 光, 教授 中村 卓史, 教授 二宮 正夫
学位規則第4条第1項該当
8
Strati, Francesco. "The microbiota-gut-brain axis: characterization of the gut microbiota in neurological disorders." Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368893.
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The human gut microbiota plays a crucial role in the functioning of the gastrointestinal tract and its alteration can lead to gastrointestinal abnormalities and inflammation. Additionally, the gut microbiota modulates central nervous system (CNS) activities affecting several aspect of host physiology. Motivated by the increasing evidences of the role of the gut microbiota in the complex set of interactions connecting the gut and the CNS, known as gut-brain axis, in this Ph.D. thesis we asked whether the gastrointestinal abnormalities and inflammation commonly associated with neurological disorders such as Rett syndrome (RTT) and Autism could be related to alterations of the bacterial and fungal intestinal microbiota.
First, since only few reports have explored the fungal component of the gut microbiota in health and disease, we characterized the gut mycobiota in a cohort of healthy individuals, in order to reduce the gap of knowledge concerning factors influencing the intestinal microbial communities. Next, we compared the gut microbiota of three cohorts of healthy, RTT and autistic subjects to investigate if these neurological disorders harbour alterations of the gut microbiota. Culture-based and metataxonomics analysis of the faecal fungal populations of healthy volunteers revealed that the gut mycobiota differs in function of individuals’ life stage in a gender-related fashion. Different fungal species were isolated showing phenotypic adaptation to the intestinal environment. High frequency of azoles resistance was also found, with potential clinical significance.
It was further observed that autistic subjects are characterized by a reduced incidence of Bacteroidetes and that Collinsella, Corynebacterium, Dorea and Lactobacillus were the taxa predominating in the gut microbiota of autistic subjects. Constipation has been associated with different bacterial patterns in autistic and neurotypical subjects, with constipated autistic individuals characterized by higher levels of Escherichia/Shigella and Clostridium cluster XVIII than constipated neurotypical subjects. RTT is a neurological disorder caused by loss-of-function mutations of MeCP2 and it is commonly associated with gastrointestinal dysfunctions and constipation. We showed that RTT subjects harbour bacterial and fungal microbiota altered from those of healthy controls, with a reduced microbial richness and dominated by Bifidobacterium, different Clostridia and Candida. The alterations of the gut microbiota observed did not depend on the constipation status of RTT subjects while this microbiota produced altered SCFAs profiles potentially contributing to the constipation itself. Phenotypical and immunological characterizations of faecal fungal isolates from RTT subjects showed Candida parapsilosis as the most abundant species isolated in RTT, genetically unrelated to healthy controls’ isolates and with elevated resistance to azoles. Furthermore these isolates induced high levels of IL-10 suggesting increased tolerance and persistence within the host. Finally, the importance of multiple sequence alignment (MSA) accuracy in microbiome research was investigated comparing three implementations of the widely used NAST algorithm. By now, different implementations of NAST have been developed but no one tested the performances and the accuracy of the MSAs generated with these implementations. We showed that micca, a new bioinformatics pipeline for metataxonomics data improves the quality of NAST alignments by using a fast and memory efficient reimplementation of the NAST algorithm.
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Strati, Francesco. "The microbiota-gut-brain axis: characterization of the gut microbiota in neurological disorders." Doctoral thesis, Università degli studi di Trento, 2017. http://hdl.handle.net/10449/38243.
Full textAbstract:
The human gut microbiota plays a crucial role in the functioning of the gastrointestinal tract and its alteration can lead to gastrointestinal abnormalities and inflammation. Additionally, the gut microbiota modulates central nervous system (CNS) activities affecting several aspect of host physiology. Motivated by the increasing evidences of the role of the gut microbiota in the complex set of interactions connecting the gut and the CNS, known as gut-brain axis, in this Ph.D. thesis we asked whether the gastrointestinal abnormalities and inflammation commonly associated with neurological disorders such as Rett syndrome (RTT) and Autism could be related to alterations of the bacterial and fungal intestinal microbiota.
First, since only few reports have explored the fungal component of the gut microbiota in health and disease, we characterized the gut mycobiota in a cohort of healthy individuals, in order to reduce the gap of knowledge concerning factors influencing the intestinal microbial communities. Next, we compared the gut microbiota of three cohorts of healthy, RTT and autistic subjects to investigate if these neurological disorders harbour alterations of the gut microbiota.
Culture-based and metataxonomics analysis of the faecal fungal populations of healthy volunteers revealed that the gut mycobiota differs in function of individuals’ life stage in a gender-related fashion. Different fungal species were isolated showing phenotypic adaptation to the intestinal environment. High frequency of azoles resistance was also found, with potential clinical significance.
It was further observed that autistic subjects are characterized by a reduced incidence of Bacteroidetes and that Collinsella, Corynebacterium, Dorea and Lactobacillus were the taxa predominating in the gut microbiota of autistic subjects. Constipation has been associated with different bacterial patterns in autistic and neurotypical subjects, with constipated autistic individuals characterized by higher levels of Escherichia/Shigella and Clostridium cluster XVIII than constipated neurotypical subjects.
RTT is a neurological disorder caused by loss-of-function mutations of MeCP2 and it is commonly associated with gastrointestinal dysfunctions and constipation. We showed that RTT subjects harbour bacterial and fungal microbiota altered from those of healthy controls, with a reduced microbial richness and dominated by Bifidobacterium, different Clostridia and Candida. The alterations of the gut microbiota observed did not depend on the constipation status of RTT subjects while this microbiota produced altered SCFAs profiles potentially contributing to the constipation itself.
Phenotypical and immunological characterizations of faecal fungal isolates from RTT subjects showed Candida parapsilosis as the most abundant species isolated in RTT, genetically unrelated to healthy controls’ isolates and with elevated resistance to azoles. Furthermore these isolates induced high levels of IL-10 suggesting increased tolerance and persistence within the host.
Finally, the importance of multiple sequence alignment (MSA) accuracy in microbiome research was investigated comparing three implementations of the widely used NAST algorithm. By now, different implementations of NAST have been developed but no one tested the performances and the accuracy of the MSAs generated with these implementations. We showed that micca, a new bioinformatics pipeline for metataxonomics data improves the quality of NAST alignments by using a fast and memory efficient reimplementation of the NAST algorithm.
10
Strati, Francesco. "The microbiota-gut-brain axis: characterization of the gut microbiota in neurological disorders." Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/1917/1/STRATI_PhD_thesis_R1_2017.01.13.pdf.
Full textAbstract:
The human gut microbiota plays a crucial role in the functioning of the gastrointestinal tract and its alteration can lead to gastrointestinal abnormalities and inflammation. Additionally, the gut microbiota modulates central nervous system (CNS) activities affecting several aspect of host physiology. Motivated by the increasing evidences of the role of the gut microbiota in the complex set of interactions connecting the gut and the CNS, known as gut-brain axis, in this Ph.D. thesis we asked whether the gastrointestinal abnormalities and inflammation commonly associated with neurological disorders such as Rett syndrome (RTT) and Autism could be related to alterations of the bacterial and fungal intestinal microbiota.
First, since only few reports have explored the fungal component of the gut microbiota in health and disease, we characterized the gut mycobiota in a cohort of healthy individuals, in order to reduce the gap of knowledge concerning factors influencing the intestinal microbial communities. Next, we compared the gut microbiota of three cohorts of healthy, RTT and autistic subjects to investigate if these neurological disorders harbour alterations of the gut microbiota. Culture-based and metataxonomics analysis of the faecal fungal populations of healthy volunteers revealed that the gut mycobiota differs in function of individuals’ life stage in a gender-related fashion. Different fungal species were isolated showing phenotypic adaptation to the intestinal environment. High frequency of azoles resistance was also found, with potential clinical significance.
It was further observed that autistic subjects are characterized by a reduced incidence of Bacteroidetes and that Collinsella, Corynebacterium, Dorea and Lactobacillus were the taxa predominating in the gut microbiota of autistic subjects. Constipation has been associated with different bacterial patterns in autistic and neurotypical subjects, with constipated autistic individuals characterized by higher levels of Escherichia/Shigella and Clostridium cluster XVIII than constipated neurotypical subjects. RTT is a neurological disorder caused by loss-of-function mutations of MeCP2 and it is commonly associated with gastrointestinal dysfunctions and constipation. We showed that RTT subjects harbour bacterial and fungal microbiota altered from those of healthy controls, with a reduced microbial richness and dominated by Bifidobacterium, different Clostridia and Candida. The alterations of the gut microbiota observed did not depend on the constipation status of RTT subjects while this microbiota produced altered SCFAs profiles potentially contributing to the constipation itself. Phenotypical and immunological characterizations of faecal fungal isolates from RTT subjects showed Candida parapsilosis as the most abundant species isolated in RTT, genetically unrelated to healthy controls’ isolates and with elevated resistance to azoles. Furthermore these isolates induced high levels of IL-10 suggesting increased tolerance and persistence within the host. Finally, the importance of multiple sequence alignment (MSA) accuracy in microbiome research was investigated comparing three implementations of the widely used NAST algorithm. By now, different implementations of NAST have been developed but no one tested the performances and the accuracy of the MSAs generated with these implementations. We showed that micca, a new bioinformatics pipeline for metataxonomics data improves the quality of NAST alignments by using a fast and memory efficient reimplementation of the NAST algorithm.
11
Östlund-Lagerström, Lina. ""The gut matters" : an interdisciplinary approach to health and gut function in older adults." Doctoral thesis, Örebro universitet, Institutionen för medicinska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-49072.
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Improved life expectancy is a triumph of modern medicine. However, today’s senior citizens are predicted to soon consume 75% of the available health-care resources. Identifying new strategies to promote a healthy ageing process has thus become a priority. In contribution to the research field of healthy ageing this thesis is focused on the health and gut function of older adults. Paper I explored ‘optimal functionality’; a new approach to put the older adult’s own perspectives on health in focus. According to the results a plethora of factors related to the body, the self and the external environment needs to be considered in order to create a comprehensive understanding of the health experience in old age. Paper II characterised senior orienteering athletes as a new model of healthy ageing, due to their significantly better percived health as compared to other free-living older adults; in particular they report better gut health. As the gut is important to health maintenance and immune function paper III explored inflammation and oxidative stress in senior orienteering athletes, and older adults with gut problems, generally finding low levels in both groups. Subsequently, Paper IV investigated the health status of free-living older adults in Örebro County and also reports the results from a randomised controlled trial evaluating the effect of a probiotic supplement on self-reported health and gut symptoms. Two-thirds of the included older adults reported gut problems, however, the probiotic intervention failed to show any effects. This thesis provides additional perspectives on older adults health and gut function, by concluding that 1) optimal functionality may be a useful concept to map areas of importance to the older adult’s health experience, 2) senior orienteers may be regarded as a suitable model to study healthy ageing, 3) the prevalence of gut problems among the general population of Swedish older adults is high, but was not improved by probiotic supplementation with Lactobacillus reuteri.
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Duca, Frank. "Altered satiation signaling in obesity : the role of nutrients, gut peptides, and gut microbiota." Paris 6, 2013. http://www.theses.fr/2013PA066078.
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Food intake is controlled by a highly complex and distributed neural system integrating many sensory inputs, most notably those arising from the gastrointestinal tract in response to a meal. Reduced sensitivity to intestinal nutrients has been proposed to be partly responsible for increased energy intake and weight gain in both animals and humans during HF feeding. However, the mechanism by which a HF diet impinges on post-ingestive intestinal feedback to promote overconsumption is unclear, as is the role of diminished satiation signaling in the development of obesity. Therefore, the work of this thesis attempts to discern the role of HF feeding in nutrient-induced satiation, by addressing the impact of GI peptides and the gut microbiota in diet-induced obesity in animals prone or resistant to obesity. In the first set of experiments, we found that diet-induced obese rats exhibited a reduced responsiveness to the suppressive effects of intragastric lipid loads, compared to diet-resistant rats. This was associated with altered intestinal gut peptides and GPRs, plausibly contributing to reduced lipid-induced satiation. In the next set of experiments, we showed that OP rats develop impaired GLP-1 signaling during maintenance on a HF diet. During chow feeding, OP and OR rats had similar sensitivity to the anorectic effects of GLP-1R agonism; however, HF feeding abolished the suppressive response to exendin-4 in OP rats. This was associated with downregulation of GLP-1R in the nodose ganglia, in addition to decreased circulating GLP-1 and L-cell counts. The last set of experiments demonstrates the influence of the gut microbiota in regulating intestinal chemosensory machinery and potentially promoting adiposity in OP rats. First, GF mice exhibited increased consumption for lipid solutions with associative decreases in intestinal satiation signals and fatty acid receptors, indicating that lack of microbiota reduces post-ingestive signaling to promote overeating. Next, we found that OP rats harbor a distinct microbiota profile compared to OR rats during HF feeding. By conventionalizing GF mice with OP microbiota, we replicated the obese phenotype, and associated reductions in peripheral and central appetite-related pathways. In summary, this thesis provides evidence that the interaction of a polygenetic susceptibility to obesity coupled with HF feeding reduces sensitivity to intestinal nutrients, by altering secretion and sensitivity to satiation signals that ultimately contributing to weight gain and adiposity. Additionally, further elucidation on the ability of an aberrant gut microbiota to influence regulatory systems involved in energy regulation could provide useful information for the development of therapeutic treatments for obesityLa prise alimentaire est contrôlée par un système complexe associant des modifications du système nerveux. Ces dysfonctionnents impliquent les outils de perception, notamment ceux en provenance de l'appareil gastro-intestinal en réponse à un repas. La diminution de la sensibilité intestinale aux nutriments a été décrite en partie comme responsable de l'apport énergétique accrue et du gain de poids chez les animaux et les humains au cours d'un régime hypercalorique. Cependant, le mécanisme par lequel un régime obesogène affecte les signaux intestinaux postprandiaux favorisant la surconsommation et leurs rôles dans la diminution du signal de satiété contribuant au développent de l'obésité reste très peu étayer. Par conséquent, le travail de cette thèse a pour but de caractériser le rôle d'un régime hypercalorique dans la diminution de la satiété induite par les nutriments, d'étudier le rôle des peptides gastro-intestinaux et de microbiote au cours d'un régime hypercalorique favorisant l'obésité chez les rats OP. Dans la première série d'expériences, nous avons constaté que les rats soumises un régime hypercalorique présentaient une réponse réduite aux effets suppresseurs de charges lipidiques gastriques comparé à des rats résistants à l'obésité (OR). Cette réponse a été associée à une altération des peptides intestinaux et des GPRS contribuant à une réduction du signal du satiété. Dans une deuxième série d'expériences, nous avons démontré que les rats obeses prônes (OP) développent une déficience de la voie de signalisation de GLP-1 au cours d'un régime hypercalorique. Sous un régime normal, les rats OP et OR avaient la même sensibilité aux effets anorexigène d'un agoniste du récepteur du GLP-1. Toutefois, le régime obesogène abolit la réponse suppressive de l'exendin-4 chez des rats OP. Ceci a été associée à une régulation négative de l'expression du GLP-1R dans les ganglions nodaux, une diminution des taux du GLP-1 circulants et du nombre des cellules L sécrétrices du GLP-1. La dernière série d'expériences démontre l'influence du microbiote intestinal dans la régulation de la chemosensibilité intestinale favorisant l'adiposité chez les rats OP. Les souris axéniques présentent une consommation accrue de solutions lipidiques associé à une diminution du signal satiétogène intestinal et des récepteurs d'acides gras. Nous avons conclu que l'absence du microbiote réduit le signal de satiété postprandial contribuant à la surconsommation des nutriments. Par la suite, nous avons identifié que les rats OP possèdent un profil du microbiote intestinal distinct de rats OR sous un régime hypercalorique. La conventionnalisation des souris axéniques avec le microbiote issu des rats OP, reproduit parfaitement le phénotype obèse avec à une réduction de la signalisation centrale et périphérique des voies contrôlant la prise alimentaire. En résumé, cette thèse apporte la preuve que l'interaction entre une prédisposition à l'obésité généralement polygénique couplée à une alimentation obesogène réduit la sensibilité intestinale aux nutriments, altérant la sécrétion et la sensibilité aux signaux de satiété. Ces effets ont pour conséquence un gain de poids et une expansion de la masse grasse. De plus, des preuves scientifiques supplémentaires sur la capacité d'un microbiote intestinal aberrant d'influencer les systèmes de régulation impliqués dans le maintien de l'homéostasie énergétique pourraient fournir des informations scientifiquement fondées afin de prévenir le développement et l'installation de l'obésité et contribuer aux progrès thérapeutiques de l'obésité
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Karmann, Alexander, Andreas Werblow, Gesine Marquardt, Sven Müller, Andrea Jurack, Ines Weinhold, and Oliver Fiala. "Gut versorgt im ländlichen Raum." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-120925.
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Der demografische Wandel vollzieht sich insbesondere in den ländlichen Gebieten Sachsens bereits in großen Schritten. Junge und hoch qualifizierte Menschen wandern weiterhin ab und die älteren bleiben zurück. Daraus resultiert ein Bevölkerungsrückgang, der zu einer Ausdünnung der Infrastruktur in diesen Gebieten führt. Insbesondere der reduzierte öffentliche Personennahverkehr schränkt die Mobilität der älteren Bevölkerung immer stärker ein. Gleichzeitig wird mit dem sich erhöhenden Altersdurchschnitt die Nachfrage nach medizinischer und pflegerischer Versorgung ansteigen. Ältere Menschen werden somit abhängig von der Unterstützung durch Familienangehörige, Freunde und Nachbarn. Stehen diese nicht zur Verfügung, sind das Verlassen des gewohnten Umfelds und der Umzug in eine stationäre Altenpflegeeinrichtung oftmals die einzige verbleibende Alternative. Dies entspricht jedoch weder den individuellen Wünschen der Betroffenen noch ist es aus volkswirtschaftlicher Perspektive sinnvoll.
Die vorliegende Projektstudie wurde aus Mitteln der Demografierichtlinie durch die Sächsische Staatsregierung gefördert und hat zum Ziel, die Lebensbedingungen älterer Menschen in dünn besiedelten Regionen so sicherzustellen, dass sie in ihrem vertrauten Lebensumfeld so lange wie möglich verbleiben können. Dazu ist es notwendig, dass Elemente der Daseinsvorsorge, wie insbesondere medizinische und pflegerische Leistungen, Waren des täglichen Bedarfs etc., in ihrem unmittelbaren Umfeld vorhanden und für sie selbstständig erreichbar sind. Um diese kleinräumige Versorgung bedarfsgerecht und kosteneffizient gestalten zu können, ist die Entwicklung, Erprobung und Evaluierung entsprechender neuer Konzeptionen notwendig. Die Innovation des vorliegenden Projektes besteht darin, dass eine Lösung entwickelt wurde, deren Elemente nach raumplanerischen und gesundheitsökonomischen Gesichtspunkten aufeinander abgestimmt sind und den Bedürfnissen der Bevölkerung im Altersbereich 70+ entspricht.
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Gatt, Marcel. "Gut failure : diagnosis and management." Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:1683.
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Background: Inadequate gut function (IGF) or intestinal failure (IF) is common, particularly in surgical patients and the critically ill. It is difficult to measure objectively, and as a consequence its effects on outcome are contentious and treatment options are limited. Because of the gut's numerous homeostatic functions IF may predispose to delayed sepsis and multiorgan failure (MOF), eventually resulting in death. Aim: To review the evidence regarding the clinical importance of IF, to define this phenomenon quantitatively, determine its effects, if any, on prognosis and to develop a therapy to treat it. Conclusion: Adequacy of gut function can be defined quantitatively by enteral tolerance. Characterized in this way, IF is independently associated with prognosis, irrespective of other single organ failures and other determinants of outcome. GSN stimulate the return of gut function and this is associated with improved outcomes. Further research and the development of other gut-directed therapies are necessary.
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Nile, Christopher John. "Investigations of avian gut antimicrobials." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405339.
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Gut, Carsten [Verfasser]. "Laserbasierte hochauflösende Pixellichtsysteme / Carsten Gut." Karlsruhe : KIT Scientific Publishing, 2018. http://www.ksp.kit.edu.
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Kearney, Sean M. (Sean Michael). "Towards engineering the gut microbiota." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119909.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
The human gastrointestinal tract is home to a dense and dynamic microbial community. Recent advancements in sequencing technology have revealed numerous relationships between the composition of these communities and human and health and disease. In some cases, researchers have shown causal relationships between the presence or absence of particular microorganisms and disease. These findings offer promise for using microorganisms or microbial communities to modulate health and disease, but to date, we lack tools and mechanistic insight needed for rational engineering of these communities. Understanding how microorganisms enter, colonize, grow, and disperse to new hosts present key considerations for rational engineering of the human gastrointestinal tract. In this thesis, I use experimental studies of the human and murine gastrointestinal tract to address these considerations. In the first study, I examined endospores and other resistant cell types in the gastrointestinal communities of unrelated humans to identify the ecological role of these states in the distribution of bacterial populations in healthy people. I used this information to infer shared roles for these organisms in successional states in the human gut, and identify host- and diet-derived metabolites as environmental signals mediating the growth and colonization of these organisms. In the second study, I examined the potential for using targeted manipulations of diet to favor selective growth and colonization by an introduced bacterium in the murine gastrointestinal tract. I showed that resource exclusivity of this bacterium permits its selective expansion in this environment, and negatively impacts the growth of other commensals. Central to the goal of rational engineering of the gut microbiota, these studies reveal ecological considerations that may promote or inhibit colonization by introduced commensals in this complex ecosystem. This work invites provides a conceptual framework for integrating systems microbial ecology with engineering design to manipulate the composition of the gastrointestinal microbiota.
by Sean M. Kearney.
Ph. D.
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Neary, Nicola Marguerite. "Gut hormones and energy homeostasis." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/7152.
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Psczolla, Katharina. "Gut verpackt : Verkaufsförderung im Versandhandel /." Saarbrücken : VDM Verlag Dr. Müller, 2008. http://d-nb.info/987976486/04.
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Vyas, Meenal, Amir Raza, Muhammad Yousaf Ali, Muhammad Aleem Ashraf, Shahid Mansoor, Ahmad Ali Shahid, and Judith K. Brown. "Knock down of Whitefly Gut Gene Expression and Mortality by Orally Delivered Gut Gene-Specific dsRNAs." PUBLIC LIBRARY SCIENCE, 2017. http://hdl.handle.net/10150/622632.
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Control of the whitefly Bemisia tabaci (Genn.) agricultural pest and plant virus vector relies on the use of chemical insecticides. RNA-interference (RNAi) is a homology-dependent innate immune response in eukaryotes, including insects, which results in degradation of the corresponding transcript following its recognition by a double-stranded RNA (dsRNA) that shares 100% sequence homology. In this study, six whitefly `gut' genes were selected from an in silico-annotated transcriptome library constructed from the whitefly alimentary canal or 'gut' of the B biotype of B. tabaci, and tested for knock down efficacy, post-ingestion of dsRNAs that share 100% sequence homology to each respective gene target. Candidate genes were: Acetylcholine receptor subunit a, Alpha glucosidase 1, Aquaporin 1, Heat shock protein 70, Trehalasel, and Trehalose transported. The efficacy of RNAi knock down was further tested in a gene-specific functional bioassay, and mortality was recorded in 24 hr intervals, six days, post-treatment. Based on qPCR analysis, all six genes tested showed significantly reduced gene expression. Moderate-to-high whitefly mortality was associated with the down-regulation of osmoregulation, sugar metabolism and sugar transport -associated genes, demonstrating that whitefly survivability was linked with RNAi results. Silenced Acetylcholine receptor subunit a and Heat shock protein 70 genes showed an initial low whitefly mortality, however, following insecticide or high temperature treatments, respectively, significantly increased knockdown efficacy and death was observed, indicating enhanced post-knockdown sensitivity perhaps related to systemic silencing. The oral delivery of gut-specific dsRNAs, when combined with qPCR analysis of gene expression and a corresponding gene-specific bioassay that relates knockdown and mortality, offers a viable approach for functional genomics analysis and the discovery of prospective dsRNA biopesticide targets. The approach can be applied to functional genomics analyses to facilitate, species-specific dsRNA-mediated control of other non-model hemipterans.
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Rocafort, Juncà Muntsa. "Gut microbiome in HIV-1 infection." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/666775.
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Una vegada el Virus de la Immunodeficiència Humana tipus 1 (en anglès HIV-1) infecta l’organisme hoste es produeix una ràpida i severa destrucció del teixit limfoide associat a tracte gastrointestinal que inclou, entre d’altres, significants pèrdues cel·lulars del sistema immunitari i epitelial de l’hoste. Seguidament es produeix un increment de la permeabilitat de la paret intestinal que permet la translocació microbiana. Així i doncs, productes i cèl·lules microbianes que normalment queden confinats i controlats dins la llum intestinal ara poden travessar l’epiteli intestinal i entrar en circulació sanguínia convertint-se en un nou focus d’activació immunitària i inflamació. Per la seva significant contribució en la patogènesis del HIV-1, gran part de la recerca en microbioma dels últims anys s’ha centrat en entendre els canvis que tenen lloc en les comunitats microbianes que habiten dins l’intestí humà després de la infecció per HIV-1 i de l’inici de tractament antiretroviral (en anglès ART).
Els primers estudis transversals van descriure relacions contradictòries entre la riquesa i diversitat microbiana a l’intestí i la infecció per HIV-1 i van suggerir una substitució de Bacteroides per Prevotella com a conseqüència de l’adquisició viral. Aquests resultats però, no s’han confirmat ni en models animals ni en estudis balancejats per grups de risc de transmissió de VIH-1. En estudis en models de primats no humans la infecció pel virus de la immunodeficiància de simi s’ha associat a una expansió de les comunitats víriques intestinals però no s’ha descrit un canvi consistent en les comunitats bacterianes.
En dues cohorts europees independents de persones amb infecció crònica per HIV-1 i persones no infectades de Barcelona (n=156) i Estocolm (n=84), els individus homosexuals (en anglès MSM), presentaven una microbiota intestinal més rica i diversa i una major abundància relativa de Prevotella, en comparació amb individus heterosexuals (no-MSM) que estaven enriquits per Bacteroides, independentment de la infecció per HIV-1. Estratificant els grups d’estudi en funció de la seva preferència sexual (MSM vs non-MSM), individus infectats amb HIV-1 presentaven valors inferiors de riquesa i diversitat bacteriana, amb els valorsmés baixos en el grup de individus amb una resposta discordant a ART. Tot i així no hi havia canvis evidents respecte una disbiosi específica de infecció per VIH-1. En la nostra cohort d’estudi de Barcelona, la dieta tenia un efecte limitat sobre la composició de la microbiota intestinal.
Per estudiar els efectes longitudinals de la infecció per HIV-1 en la microbiota intestinal, vam fer un seguiment de 9-18 mesos a 49 persones de Moçambic diagnosticades amb infecció recent per HIV-1 i 54 persones no infectades, i les vam comparar amb dos grups de persones amb infecció crònica per HIV-1, tan si estaven amb ART (n=27) o no (n=71). En aquest estudi, seguint la infecció recent per HIV-1, es produïa una major secreció d’Adenovirus en femta, la qual persistia en infecció crònica i no desapareixia amb l’administració de ART. Paral·lelament també vam descriure canvis transitoris no específics en la riquesa i la composició bacteriana després de la infecció recent per HIV-1. Malgrat certa resiliència inicial al canvi, sí que s’evidenciava una signatura en quan a composició bacteriana en individus amb infecció crònica per HIV-1. Aquesta signatura, que incloïa pèrdua de Akkermansia, Anaerovibrio, Bifidobacterium i Clostridium, ja ha estat prèviament associada a inflamació crònica, anergia de limfòcits T CD8+ i desordres metabòlics.
En conclusió: 1) La preferència sexual és un factor de confusió important que s’hauria de considerar d’ara endavant, especialment en estudis de microbioma intestinal i HIV-1; 2) La microbiota intestinal sembla ser inicialment resilient a canviar després la infecció per HIV-1 però amb el pas del temps i progressió a fase crònica sí que apareix una signatura bacteriana amb perfil pro-inflamatori; i 3) Els canvis en la microbiota intestinal no només afecten les comunitats bacterianes sinó també, com a mínim, les comunitats víriques.Soon after Human Immunodeficiency Virus type 1 (HIV-1) infection, a severe and rapid depletion of the gut-associated lymphoid tissue occurs, including significant loss of both, immune and epithelial host cells. This is followed by an increased permeability of the intestinal cell lining which facilitates microbial translocation. Microbial cells and products that are usually contained and controlled within the intestinal lumen, can now circulate in the bloodstream and become a new source for immune activation and inflammation. Because of the significant immune imbalance in the GALT after HIV-1 infection, recent microbiome research has focused on understanding the changes occurring in the microbial communities inhabiting the human gut after HIV-1 perturbation and in response to antiretroviral treatment (ART). Initial cross-sectional studies provided contradictory associations between gut microbial richness and diversity and HIV-1 infection and suggested shifts from Bacteroides to Prevotella predominance following viral infection. Nonetheless, these results have not been confirmed in animal models or in studies matched for HIV-1 transmission risk groups. For instance, in non-human primate models Simian Immunodeficiency Virus infection is followed by expansion of enteric virome but has a limited impact on the gut bacteriome. In two independent European cross-sectionals cohorts of chronically HIV-1-infected subjects and uninfected controls, in Barcelona (n=156) and Stockholm (n=84), men-who-have-sex-with-men (MSM) showed a Prevotella-enriched gut microbiota and higher microbial richness and diversity compared to non-MSM individuals who predominantly showed a Bacteroides-enriched microbiota, regardless of HIV-1 infection. After stratifying for sexual orientation (MSM vs. non-MSM), we described lower microbial richness and diversity in HIV-1 infected subjects, more so in subjects with an immune-discordant response to ART, but there was no solid evidence of an HIV-1-specific dysbiosis. In our Barcelona cohort, diet did not have a major impact on gut microbiota composition. To understand the longitudinal effects of HIV-1 infection on the human gut microbiota, we prospectively followed 49 Mozambican subjects diagnosed with recent HIV-1 infection and 54 uninfected controls for 9-18 months and compared them with 98 chronically HIV-1-infected subjects ART-treated (n=27) or not (n=71). Recent HIV-1infection was characterized by increased fecal Adenovirus shedding, which persisted during chronic HIV-1 infection and did not resolve with ART. Recent HIV-1 infection was also followed by transient non-HIV-1-specific changes in the gut bacterial richness and composition. Despite early resilience to change, an HIV-1-specific signature in the gut bacteriome could be eventually identified in chronically HIV-1-infected subjects. Such signature featured depletion of Akkermansia, Anaerovibrio, Bifidobacterium, and Clostridium, and has been previously associated with chronic inflammation, CD8+ T-cell anergy and metabolic disorders. In conclusion: 1) Sexual practice is an important confounding factor in microbiome studies that needs to be considered, especially in HIV-1-gut microbiota studies; 2) Gut microbiota is initially resilient to change right after HIV-1 acquisition but a pro-inflammatory-bacterial signature eventually appears in chronic phases of the infection, and 3) Changes on the gut microbiota do not only impact bacterial communities, but, at least, also viral communities.
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Tikka, P. (Piiastiina). "Narration in Jeanette Winterson's Gut Symmetries." Master's thesis, University of Oulu, 2002. http://urn.fi/urn:nbn:fi-fe19991199.
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Benskin, Clare McWilliam Haldane. "Bacterial communities in the avian gut." Thesis, Lancaster University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539637.
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Parks, Rowan Wesley. "Gut barrier function in obstructive jaundice." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361292.
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Patterson, R. N. "Gut-lung interactions in airway disease." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419495.
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McCullough, Fiona S. W. "Vitamin A - gut integrity and bioavailability." Thesis, University of Ulster, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326129.
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Fu, Tiantian. "Quaternary amine metabolism in gut microbiota." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/95877/.
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Quaternary amines such as choline and carnitine are essential nutrients for humans supplied from daily food; however, quaternary amines metabolism by gut microbiota can lead to the development of various diseases, including non-alcoholic fatty liver disease and cardiovascular disease. It is hypothesized that both diseases are promoted by microbial catabolism of choline and carnitine to trimethylamine (TMA). Proteus mirabilis is a Gram-negative gut proteobacterium, which can metabolize choline anaerobically to form TMA. I demonstrated that the identified cutC gene is essential for choline degradation and subsequent TMA production in this bacterium. Using P. mirabilis as the model, I investigated the physiological role of quaternary amine metabolism from the bacterial perspective and demonstrated that P. mirabilis can rapidly uptake and degrade choline to enhance growth rate, cell yield and swarming speed under anaerobic and microaerophilic conditions. I also provide the first evidence of a novel choline-metabolizing microcompartment, which is present in both vegetative and swarming cells supplemented with choline. Another important dietary source of TMA in human gut is carnitine. I used two model proteobacteria Acinetobacter baumannii and Escherichia coli in this project to investigate the role of carnitine metabolism to TMA in health and disease. A. baumannii and E. coli can use carnitine as a growth substrate to produce TMA. To better understand the role of quaternary amine metabolism in host health and disease, I used Caenorhabditis elegans model to investigate carnitine metabolism on the life span of the worm. My data suggest that malate, the degradation product of carnitine, extends the life span of C. elegans fed on A. baumannii or E. coli. Together, my study reveals that choline and carnitine metabolism as an adaptation strategy for gut proteobacteria and contributes to better understand the ecology of these TMA-forming gut bacteria in health and disease.
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Engevik, Melinda A. "Ion Transport and the Gut Microbiota." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1397466973.
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Thaler, Rolf. "Verschnittplanung in gut- und schlechtstrukturierten Planungssituationen /." Münster ; Hamburg : Lit, 1991. http://catalogue.bnf.fr/ark:/12148/cb37439236c.
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McMurran, Christopher Edward. "CNS remyelination and the gut microbiota." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277088.
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Remyelination describes the regeneration of myelin sheaths, and is considered one of the most promising strategies for improving the prognosis of demyelinating diseases such as multiple sclerosis. Data from animal models and human studies have shown that remyelination can occur extensively in the central nervous system (CNS), leading to functional recovery and axonal protection. However, remyelination does not always proceed to completion, and its failure is associated with progressive neurological disability. Thus, there is clinical need for interventions that can optimise the conditions for remyelination. Recent advances in genomics and animal husbandry have kindled an interest in the microbiome as a means to influence processes throughout the body. Our commensal microbes communicate with host cells at epithelial barriers, stimulate neural and endocrine axes and directly produce a plethora of long-range signalling molecules. Critically, the development and maintenance of the immune system depend on signals from the microbiota, and we know that a well-coordinated immune response is a key determinant of the success of remyelination. This thesis explores how the microbiome can influence CNS remyelination. To do so, I have studied remyelination in three murine models of microbiome alteration. Firstly, long-term oral administration of an antibiotic cocktail was used to deplete the microbiota of adult mice. Following focal demyelination, these mice had deficits in their inflammatory response, clearance of myelin debris and differentiation of new oligodendrocytes from oligodendrocyte progenitor cells (OPCs). Faecal microbial transplant was able to rescue aspects of the inflammatory response and phagocytosis, but not OPC differentiation. Secondly, I looked at remyelination in germ-free (GF) mice following cuprizone-induced demyelina- tion. As with the antibiotics-treated mice, there were deficits in inflammation following demyelination, which tended to peak later than in control mice. Finally, I investigated the potential of a therapeutic probiotic (VSL#3) to improve remyelination in aged mice. In contrast to antibiotic treatment, probiotic administration caused a slight enhancement in the onset of inflammation following focal demyelination. However, there was no significant improvement in OPC differentiation or toluidine blue rank analysis, suggesting these changes in inflammation were not sufficient to positively modulate remyelination. The results from these three studies introduce a significant but previously unconsidered environmental influence on remyelination in the CNS. Whilst the effects are subtle relative to more direct interventions, the microbiome can be manipulated simply and non-invasively, which may provide a useful adjunct to other strategies for optimising remyelination.
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Prosdocimi, E. M. "GUT-BACTERIA SYMBIOSIS IN INSECT PESTS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/252503.
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Insects are one of the most fascinating taxa on Earth: their diversity, diffusion, colonization of different niches are unparalleled in the animal kingdom. Besides, they have a remarkable impact on human life: they are parasites for people, animals and crops, vectors of diseases, pollinators, and even breeding animals (e.g. honeybees, silkworms). This extraordinary evolutionary success and diversification is partially due to the symbiotic relationships that insects have with a wide range of bacteria. These symbionts can be divided into primary, secondary symbionts and gut bacteria. Primary symbionts are found in very specialized cells (the bacteriocytes), strictly maternally transmitted and not cultivable. They are essential for their host, and vice-versa: they can actually be considered part of a single organism called “holobiont”. Secondary symbionts are not necessary for the host survival, although often beneficial, and they can inhabit various organs and tissues. In this category fall also reproductive parasites, as Wolbachia, which spreads in the population by maternal transmission, manipulating the reproduction of the host to favour the birth of infected daughters. Finally, gut bacteria are a more vague category, comprising organisms that live in the insect intestine because they are ingested with the diet, but also symbionts that establish a close relationship with the host, being essential for its survival and development. The roles of all these microorganisms are, to different extents, important for the insect physiology. Primary symbionts are generally essential to complement unbalanced diets and secondary ones contribute to the host fitness, while reproduction parasites deeply affect the reproduction mode of their hosts. Even commensals have been demonstrated to influence the development, mating choice and immune responses in Drosophila flies. For these reasons, the understanding of the biology of an insect can not do without the characterisation of its microbiota.
In the second chapter of my PhD thesis, a review on the microbial ecology techniques applied to the study of insect microbial communities gives an overview on the methods that can be applied to this purpose. On one hand, molecular analyses based on the 16S gene sequencing, such as 16S rRNA barcoding (pyrotag) and Denaturing Gradient Gel Electrophoresis (DGGE) are the most powerful methods to get a complete picture of the microbial community composition and structure. Microscopic localisation of symbionts can be also achieved by Fluorescent In Situ Hybridisation. On the other hand, the isolation of bacteria allows to deeply characterize the cultivable fraction, verifying through direct in vitro tests the activities of the strains. Taking advantage of a strain collection isolated from the target insect, the symbiotic relationship can be investigated through in vivo experiments. The more common ones involve i) the labeling of the strains with fluorescent proteins and the recolonization of the insects, to evaluate their localisation and colonisation ability, ii) the assessment of the detrimental effects of symbionts deprivation on the hosts, and iii) the comparison of insects monoassociated with different strains to check the effects on host fitness. To further analyse the interaction between bacteria and their hosts from a genetic point of view, advanced techniques, such as Signature Tagged Mutagenesis or In Vivo Expression Technology, can be performed. Many of these techniques have been applied in the case studies here presented, in which the microbial communities associated to three insect pests have been characterised.
In the third chapter is presented a study on the spotted-wing fly Drosophila suzukii. Unlike its relative D. melanogaster, which feeds on rotten fruit, this fly feeds and lays eggs on healthy fruits. The most damaged crops are members of the Drupaceae family (e.g. cherries) and berries (strawberries, raspberries, blueberries). The bacterial community associated to this pest have been characterised with a focus on acetic acid bacteria (AAB), important symbionts of many sugar-feeding insects. According to our findings, D. suzukii harbours a diverse community of AAB, detected both in the isolate collection and in culture-independent screenings (pyrotag, DGGE). They are primarily localised in the gut, attached to the peritrophic matrix, as showed by FISH micrographs. The ability of three AAB species (Gluconobacter oxydans, Acetobacter tropicalis and Acetobacter indonesiensis) to colonise the gut has been proved by recolonization experiments of the insect using GFP-marked strains.
In the fourth chapter, the bacterial community of the wood-feeding beetle Rhynchophorus ferrugineus has been analysed. Commonly named Red Palm Weevil (RPW), this insect is an important pest for palm trees. The plants are damaged mainly by the larvae, which dig tunnels in the trunks until pupation. Bacteria associated to the red palm weevil have been studied primarily by molecular means (pyrotag). Our results outline that the bacteria hosted by R. ferrugineus are mainly acquired from the environment while feeding. Indeed, a sharp difference has been registered between field-caught and bred specimens. While field caught RPW harbour more bacterial taxa which are in common with their feeding plants, the animals fed on apple in the laboratory show a higher prevalence of lactic acid and acetic acid bacteria, which presumably grow on the rotten fruit. The latter result is further confirmed by the bacterial isolations performed on apple-fed specimens. Besides, the DNA sequence of a primary symbiont, Candidatus Nardonella, has been detected. This bacterium has been shown to inhabit a wide range of insects of the same family of the RPW, Curculionidae.
The fifth chapter is about the gut bacterial community of Psacothea hilaris hilaris. Native of Japan and east China, this longicorn beetle (family: Cerambicidae) arrived in Italy as a consequence of the wood trade, and settled as a stable population in a small area in Como province. Its larvae dig tunnels in the trunks of the trees of the Moraceae family, while the adults feed on leaves. The most damaged by its feeding habits are mulberry and fig trees. This beetle hosts a variegate gut microbiota, that, as shown by DGGE, greatly changes according to the diet and to the gut tract examined. The cultivable fraction of this microbiota has been tested for several activities that proved the capability of the community as a whole to exploit the food sources in the insect gut (primarily, sugars from plant cell walls) and to assist their host in carbon and nitrogen absorption. Thus, even if acquired from the environment, these bacteria seem to be adapted to a symbiotic lifestyle.
From the comparison among these three studies, some conclusions can be drawn. All three case studies outline the importance of the diet in shaping the insect microbial community. In detail, wild insects always show higher diversity and individual variability in their associated microbiota. Reared insects appear, on the contrary, dominated by the species that can rapidly grow on laboratory diets, such as Lactobacillales and Enterobacteriales. Secondly, these studies depict a more accurate image of the commensal bacteria, which are not merely acquired by chance through feeding, but are capable to actively colonize insect guts, and to efficiently exploit this niche to multiply and spread in the environment. Finally, the research data point out that the origin and the function of many of the organisms detected in insects are yet poorly understood. For this reason, these studies can be considered a basis to for future research, aimed to a more in-depth understanding of the roles of these bacteria and their interactions with the hosts.
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Lackner-Frey, Elisabeth. "Öffentliche Güter im individuellen Entscheidungskalkül : Möglichkeiten und Grenzen verschiedener Präferenzenthüllungsverfahren /." Hamburg : Kovač, 2004. http://www.gbv.de/dms/zbw/391828983.pdf.
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Pinget, Gabriela Veronica. "The Relationship Between Diet, Gut Health and Inflammatory Disease." Thesis, University of Sydney, 2019. https://hdl.handle.net/2123/22988.
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Gut homoeostasis is central to health outcomes and its disruption is linked to a growing number of inflammatory diseases. Diet plays a major role in shaping gut homeostasis. However, while studies often focused on the effects of macronutrients, the impact of dietary additives, particularly titanium dioxide (E171), is less well defined. Additionally, while many studies focus on how altered gut homeostasis may increase predisposition to inflammatory diseases, few studies have investigated whether inflammatory diseases itself can trigger changes to gut homeostasis. This thesis seeks to understand how the common food additive, E171 and the inflammatory disease, psoriasis each impact key features of gut homeostasis. Investigations reveal that oral consumption of E171 in mice resulted in changes to the release of bacterial metabolites in vivo and promoted biofilm formation by colonic commensal bacteria in vitro. This was accompanied by increased transcription of inflammatory cytokines, reduced colonic crypt length and increased production of antimicrobial peptides in the colon, altogether indicating the presence of low-grade colonic inflammation. Through the use of the imiquimod-induced mouse model of psoriasis we also reveal that this inflammatory skin condition induced proliferation of colonic macrophages, stimulated the transcription of macrophage-associated cytokines and led to microbial dysbiosis. Migrating monocytes were not found to be contributing to increased macrophage populations within the colon of psoriatic mice, although, their migration to the dermis was found to promote disease pathogenesis. This thesis reveals new insights into the ways that diet and inflammatory diseases affect gut homeostasis. A deepened understanding of the complex interactions between gut homeostasis, diet and inflammatory disease may provide new clinical targets for disease prevention and management.
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Flohrer, Marco. "UMTS - Mehr als nur zum Telefonieren gut." Universitätsbibliothek Chemnitz, 2001. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200100471.
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Gemeinsamer Workshop von Universitaetsrechenzentrum und Professur "Rechnernetze und verteilte Systeme" der Fakultaet fuer Informatik der TU Chemnitz.
Workshop-Thema: Mobilitaet
Technik und Anwendungsmöglichkeiten des Mobilfunkstandards der 3. Generation unter Einbeziehung von Vorgänger-, Alternativ-, sowie Nachfolgesystemen.
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Nistor, Nicolae, and Monika Schustek. "Wie gut sind die guten alten FAQs?" Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-76312.
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Die zunehmende Nutzung der digitalen Medien im Rahmen des universitären Bildungsmanagements ist mit neuen Arbeitsweisen verknüpft. Dafür brauchen Hochschulmitarbeiter, Doktoranden und Studierende vielfältige Kompetenzen, die technisches Wissen und Können einschließen und im formellen Rahmen nicht vollständig abgedeckt werden können. Als Alternative zur Unterstützung durch spezialisierte Einrichtungen (wie z.B. IT-Helpdesks) bietet sich die gemeinsame Wissenskonstruktion und -kommunikation in der akademischen Wissensgemeinschaft an. Dabei stellt sich allerdings die Frage, inwieweit und unter welchen Bedingungen die mediengestützten, kulturellen Artefakte wie FAQ-Sammlungen, die diese Lernprozesse unterstützen können, von den Akteuren akzeptiert werden. Die vorliegende Arbeit stellt zunächst einen theoretischen Hintergrund der Wissenskommunikation in Wissensgemeinschaften vor. Dieser umfasst zum einen den Community of Practice-Ansatz (Lave & Wenger, 1991) und zum anderen die Unified Theory of Acceptance and Use of Technology (Venkatesh, Morris, Davis & Davis, 2003). Daraus wird ein Forschungsmodell abgeleitet, das die Zusammenhänge zwischen der Akzeptanz von mediengestützten kulturellen Artefakten, der Partizipation in der Wissensgemeinschaft und der Bereitschaft zur Wissenskommunikation erklärt. Anschließend wird das Modell durch eine empirische Studie überprüft. Auf theoretischer Ebene trägt die Studie zur Annäherung der Medienakzeptanztheorien an die Perspektive des situierten Lernens bei. Als medienpädagogische Konsequenz bietet das Modell Ansatzpunkte zur Förderung der Wissenskommunikation in akademischen Wissensgemeinschaften.
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Lang, Emily Rowena. "Development and patterning of the avian gut." Thesis, Royal Veterinary College (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522620.
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Ramage, John. "Permeability of the healthy and inflamed gut." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46519.
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Woodhouse, Fiona. "Selecting potential teachers : 'gatekeepers and gut feelings'." Thesis, University of Huddersfield, 2009. http://eprints.hud.ac.uk/id/eprint/7057/.
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One route to becoming a qualified teacher in England is to complete a Post Graduate Certificate in Education. The first obstacle for these potential teachers is to be successfully selected onto a course. The potential teachers need to possess the appropriate personal and intellectual qualities required to become teachers. This study has sought to uncover how the gatekeepers to the teaching profession- the subject tutors and practising teachers involved in the selection process make the decisions as to whether a potential teacher has these appropriate personal qualities. The study considered what the potential teachers own construct of a teacher was, as they arrived for the selection interview. It explored what the practising teachers and subject tutors consider as appropriate qualities for these potential teachers. This research used grounded theory as the methodology for exploring how these potential teachers are selected onto an Initial Teacher Education programme. The analysis of the research has led to five emerging themes and a possible model to illustrate how the subject tutors and teachers select these potential teachers. The research highlights that the subject tutor interviews are semi structured in nature. It suggests that subject tutors expect these potential teachers to exhibit some evidence of six groups of ‘qualities’. These include; personal qualities (including the ability to reflect on their own development), subject knowledge for teaching, enthusiasm for the subject, experiences of observing or working with pupils, some knowledge of schools settings and some knowledge of the teaching profession. The practising teachers similarly expect potential teachers to have, personal qualities, vocational qualities, some knowledge of their subject and some knowledge of teaching. The research suggests that there is congruence between what the gatekeepers to the teaching profession often refer to as their ‘gut feelings’ about the potential teachers and the qualities referred to in research studies. This may give the gatekeepers greater confidence that their professional judgements are secure, and that ‘gut feelings’ masquerading as professional judgment can be relied upon!
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Bebris, Kristaps. "Local adaptation of Grauer's gorilla gut microbiome." Thesis, Uppsala universitet, Zooekologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-326705.
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The availability of high-throughput sequencing technologies has enabled metagenomicinvestigations into complex bacterial communities with unprecedented resolution andthroughput. The production of dedicated data sets for metagenomic analyses is, however, acostly process and, frequently, the first research questions focus on the study species itself. Ifthe source material is represented by fecal samples, target capture of host-specific sequencesis applied to enrich the complex DNA mixtures contained within a typical fecal DNA extract.Yet, even after this enrichment, the samples still contain a large amount of environmentalDNA that is usually left unanalysed. In my study I investigate the possibility of using shotgunsequencing data that has been subjected to target enrichment for mtDNA from the hostspecies, Grauer’s gorilla (Gorilla beringei graueri), for further analysis of the microbialcommunity present in these samples. The purpose of these analyses is to study the differencesin the bacterial communities present within a high-altitude Grauer’s gorilla, low-altitudeGrauer’s gorilla, and a sympatric chimpanzee population. Additionally, I explore the adaptivepotential of the gut microbiota within these great ape populations.I evaluated the impact that the enrichment process had on the microbial community by usingpre- and post-capture museum preserved samples. In addition to this, I also analysed the effectof two different extraction methods on the bacterial communities.My results show that the relative abundances of the bacterial taxa remain relatively unaffectedby the enrichment process and the extraction methods. The overall number of taxa is,however, reduced by each additional capture round and is not consistent between theextraction methods. This means that both the enrichment and extraction processes introducebiases that require the usage of abundance-based distance measures for biological inferences.Additionally, even if the data cannot be used to study the bacterial communities in anunbiased manner, it provides useful comparative insights for samples that were treated in thesame fashion.With this background, I used museum and fecal samples to perform cluster analysis to explorethe relationships between the gut microbiota of the three great ape populations. I found thatpopulations cluster by species first, and only then group according to habitat. I further foundthat a bacterial taxon that degrades plant matter is enriched in the gut microbiota of all threegreat ape species, where it could help with the digestion of vegetative foods. Another bacterialtaxon that consumes glucose is enriched in the gut microbiota of the low-altitude gorilla andchimpanzee populations, where it could help with the modulation of the host’s mucosalimmune system, and could point to the availability of fruit in the animals diet. In addition, Ifound a bacterial taxon that is linked with diarrhea in humans to be part of the gut microbiotaof the habituated high-altitude gorilla population, which could indicate that this pathogen hasbeen transmitted to the gorillas from their interaction with humans, or it could be indicative ofthe presence of a contaminated water source.
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Penders, Johnny. "Gut microbiota and atopic manifestations in infancy." Maastricht : Maastricht : Universiteit Maastricht ; University Library, Universiteit Maastricht [host], 2007. http://arno.unimaas.nl/show.cgi?fid=9167.
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Bläser, Ralf. "Gut situiert: Bankwatch-NGOs in Washington, DC." Köln Geograph. Inst. der Univ. zu Köln, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&docl̲ibrary=BVB01&docn̲umber=014576354&linen̲umber=0001&funcc̲ode=DBR̲ECORDS&servicet̲ype=MEDIA.
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Majani, Ruby. "Gut construction : scaffolds for intestinal tissue engineering." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/29319/.
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Forming tissues in the laboratory to replace diseased or dysfunctional tissue or act as models for drug treatment is the goal of tissue engineering. The large intestine epithelium (colon surface) is a tissue which could benefit from both diseased and non-diseased models for the purpose of tackling colon cancer causes and treatments. Scaffolds (cell supports) are a pivotal part in many tissue engineering strategies. This thesis describes the design and production of two separate scaffolds based on the degradable polymer poly(lactic-co-glycolic acid) (PLGA). The first was a two dimensional scaffold to mimic the intestinal basement membrane which was modified with an oxygen plasma. The changes to the surface due to plasma and the degradation properties of the scaffold were extensively studied with SEM, XPS, AFM and GPC. The data showed that the oxygen plasma induced surface porosity and associated changes to surface roughness. The surface chemistry as detected by XPS was unchanged by both plasma treatment and degradation in buffered solution. The plasma treatment did lead to a dramatic loss in molecular weight but the degradation profile of both the untreated and etched films was similar. Extensive cell studies with SEM, live/dead, alamarBlue and Hoechst DNA assays showed that intestinal cells on the plasma treated scaffold was enhanced in terms of morphology, metabolic activity and proliferation. Finally, a two dimensional co-culture model using epithelial and myofibroblasts cell lines on the modified PLGA scaffold was achieved. The second scaffold was a three dimensional scaffold bearing the crypt like architecture of the colon. An accurate mould produced through electron beam lithography using dimensions measured from mouse histological sections. PLGA particles were used to fill the mould and sintered to produce the scaffold. A unique cell seeding approach using cell sheets was used. The cell sheets were produced on plasma polymers of acrylic acid and the discharge power was shown to affect surface wettability, chemistry and cell viability. The cell sheet approach proved to enhance cell attachment to the scaffold compared to individual cell seeding. Finally, a bilayer scaffold with model protein to mimic Wnt protein presence in the lower half of the crypt was studied with ToF-SIMS.
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Ganesh, Bhanu Priya. "Host-microbe interactions in the inflamed gut." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/6955/.
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Initiation and perpetuation of inflammatory bowel diseases (IBD) may result from an exaggerated mucosal immune response to the luminal microbiota in a susceptible host. We proposed that this may be caused either 1) by an abnormal microbial composition or 2) by weakening of the protective mucus layer due to excessive mucus degradation, which may lead to an easy access of luminal antigens to the host mucosa triggering inflammation.
We tested whether the probiotic Enterococcus faecium NCIMB 10415 (NCIMB) is capable of reducing chronic gut inflammation by changing the existing gut microbiota composition and aimed to identify mechanisms that are involved in possible beneficial effects of the probiotic. To identify health-promoting mechanisms of the strain, we used interleukin (IL)-10 deficient mice that spontaneously develop gut inflammation and fed these mice a diet containing NCIMB (106 cells g-1) for 3, 8 and 24 weeks, respectively. Control mice were fed an identically composed diet but without the probiotic strain. No clear-cut differences between the animals were observed in pro-inflammatory cytokine gene expression and in intestinal microbiota composition after probiotic supplementation. However, we observed a low abundance of the mucin-degrading bacterium Akkermansia muciniphila in the mice that were fed NCIMB for 8 weeks. These low cell numbers were associated with significantly lower interferon gamma (IFN-γ) and IFN-γ-inducible protein (IP-10) mRNA levels as compared to the NCIMB-treated mice that were killed after 3 and 24 weeks of intervention. In conclusion, NCIMB was not capable of reducing gut inflammation in the IL-10-/- mouse model.
To further identify the exact role of A. muciniphila and uncover a possible interaction between this bacterium, NCIMB and the host in relation to inflammation, we performed in vitro studies using HT-29 colon cancer cells. The HT-29 cells were treated with bacterial conditioned media obtained by growing either A. muciniphila (AM-CM) or NCIMB (NCIMB-CM) or both together (COMB-CM) in Dulbecco’s Modified Eagle Medium (DMEM) for 2 h at 37 °C followed by bacterial cell removal. HT-29 cells treated with COMB-CM displayed reduced cell viability after 18 h (p<0.01) and no viable cells were detected after 24 h of treatment, in contrast to the other groups or heated COMB-CM. Detection of activated caspase-3 in COMB-CM treated groups indicated that death of the HT-29 cells was brought about by apoptosis. It was concluded that either NCIMB or A. muciniphila produce a soluble and heat-sensitive factor during their concomitant presence that influences cell viability in an in vitro system. We currently hypothesize that this factor is a protein, which has not yet been identified.
Based on the potential effect of A. muciniphila on inflammation (in vivo) and cell-viability (in vitro) in the presence of NCIMB, we investigated how the presence of A. muciniphila affects the severity of an intestinal Salmonella enterica Typhimurium (STm)-induced gut inflammation using gnotobiotic C3H mice with a background microbiota of eight bacterial species (SIHUMI, referred to as simplified human intestinal microbiota). Presence of A. muciniphila in STm-infected SIHUMI (SIHUMI-AS) mice caused significantly increased histopathology scores and elevated mRNA levels of IFN-γ, IP-10, tumor necrosis factor alpha (TNF-α), IL-12, IL-17 and IL-6 in cecal and colonic tissue. The number of mucin filled goblet cells was 2- to 3- fold lower in cecal tissue of SIHUMI-AS mice compared to SIHUMI mice associated with STm (SIHUMI-S) or A. muciniphila (SIHUMI-A) or SIHUMI mice. Reduced goblet cell numbers significantly correlated with increased IFN-γ (r2 = -0.86, ***P<0.001) in all infected mice. In addition, loss of cecal mucin sulphation was observed in SIHUMI-AS mice. Concomitant presence of A. muciniphila and STm resulted in a drastic change in microbiota composition of the SIHUMI consortium. The proportion of Bacteroides thetaiotaomicron in SIHUMI, SIHUMI-A and SIHUMI-S mice made up to 80-90% but was completely taken over by STm in SIHUMI-AS mice contributing 94% to total bacteria. These results suggest that A. muciniphila exacerbates STm-induced intestinal inflammation by its ability to disturb host mucus homeostasis.
In conclusion, abnormal microbiota composition together with excessive mucus degradation contributes to severe intestinal inflammation in a susceptible host.Die Initiation and die Manifestation von entzündlichen Darmerkrankungen (inflammatory bowel diseases - IBD) können aus einer übersteigerten mukosalen Immunreaktion auf die luminale Mikrobiota in einem empfänglichen Wirt resultieren. Wir schlagen vor, dass dies entweder durch 1) eine abnormale mikrobielle Zusammensetzung oder 2) die Abschwächung der schützenden Schleimschicht, eingeleitet durch deren fortgeschrittenen Abbau, verursacht werden kann. Diese Entwicklung ermöglicht einen erleichterten Zugang des luminalen Antigens zu der Mukosa des Wirts und somit die Auslösung der Entzündung. Wir haben getestet, ob das probiotische Bakterium Enterococcus faecium NCIMB 10415 (NCIMB) in der Lage ist, der chronischen Darmentzündung durch Veränderung der Zusammensetzung der Darmmikrobiota entgegenzuwirken und strebten an, die zugrunde liegenden Mechanismen der probiotischen Wirkungsweise zu identifizieren. Für die Aufklärung der gesundheitsfördernden Mechanismen dieses Bakterienstammes wurden Interleukin-10 defiziente Mäuse verwendet, die spontan eine Darmentzündung entwickeln. Den Mäusen wurde für 3, 8 und 24 Wochen eine NCIMB enthaltende Diät verabreicht. Nach der Fütterung waren keine eindeutigen Unterschiede zwischen den Gruppen hinsichtlich der Genexpression von pro-inflammatorischen Zytokinen und der Zusammensetzung der Darmmikrobiota zu beobachten, obwohl eine geringere Zellzahl des schleimabbauenden Bakteriums Akkermansia muciniphila in den mit NCIMB gefütterten Mäusen nach 8 Wochen festgestellt wurde. Daraus folgt, dass NCIMB nicht in der Lage ist, dem Verlauf der Darmentzündung im IL-10-/--Mausmodell entgegenzuwirken. In der nachfolgenden Studie wurde untersucht, wie die Anwesenheit von A. muciniphila den Ausprägungsgrad einer intestinalen Salmonella enterica Typhimurium (STm) induzierten Darmentzündung beeinflusst. Dafür wurden gnobiotische C3H-Mäuse mit einem mikrobiellen Hintergrund von acht Bakterienspezies (SIHUMI) verwendet. Die gleichzeitige Anwesenheit von A. muciniphila und STm verursachte eine drastische Veränderung der Mikrobiota-Zusammensetzung des SIHUMI-Konsortiums. Diese Ergebnisse zeigen, dass A. muciniphila durch seine Fähigkeit, die Homöostase/Selbstregulation der Schleimbildung zu stören, die STm-induzierte Darmentzündung verschärft. Es kann geschlußfolgert werden, dass eine abweichende Zusammensetzung der Mikrobiota in Kombination mit einem massiven Abbau des Mucus zur schweren intestinalen Entzündung im empfänglichen Wirt beiträgt.
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Knight, Sue. "Metabolism of dietary polyphenols by gut flora." Thesis, University of Surrey, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402814.
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Suau, Antonia. "Molecular characterisation of the human gut microflora." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367720.
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Spreckley, Eleanor. "The regulation of appetite by gut hormones." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/56218.
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Food intake is essential to life, and thus the drive to eat is a priority. Hunger and satiety are governed by homeostatic and hedonic pathways. The homeostatic control of food intake is primarily mediated by nuclei of the hypothalamus and brainstem, while non-homeostatic control is predominantly afforded by the mesocortical and mesolimbic pathways. Hedonic drive to eat may override homeostatic control, leading to increased food intake. The increasing intake of calorie-dense, highly palatable food has contributed to escalating levels of obesity, which now represents a major public health burden. Thus, the development of appetite-reducing agents to combat the obesity epidemic is a priority. Non-specific appetite inhibitors often result in side-effects such as alterations in blood pressure, locomotor activity and disrupted eating patterns. If an appetite-reducing agent is observed to be acting specifically, it may represent a better target for the development of anti-obesity drugs. The anorectic gut hormones, peptide YY (PYY) and glucagon-like-peptide-1 (GLP-1), reduce food intake by peripheral mechanisms, and also have effects on central homeostatic and hedonic pathways. However, exogenous administration of these peptides results in nausea in humans and aversion in rodents at higher doses. This project investigated the effects of peripheral administration of GLP-1 and PYY on food intake, cardiovascular parameters and behaviour in rats. Feeding studies in fasted animals identified 1.5 nmol/kg as the minimally effective anorectic dose of PYY, while conditioned taste aversion (CTA) was present from doses of 2.5 nmol/kg PYY. Peripheral administration of 300 nmol/kg PYY significantly decreased food intake and led to significant changes in blood pressure. This dose also produced a trend for increased latency to feeding, and decreased activity. In c-Fos studies, peripheral administration of 300 nmol/kg PYY increased neuronal activation in several nuclei of the mesocorticolimbic pathways, and the area postrema (AP). Signalling in these pathways may mediate the aversive properties of PYY, while the AP may detect concurrent alterations in cardiovascular parameters. Feeding studies in fasted animals identified 10 nmol/kg as the minimally effective anorectic dose of GLP-1. Food intake was significantly reduced by 300 nmol/kg GLP-1, including decreased intake in the first feeding bout and a trend for increased latency to feeding. The same dose significantly depressed ambulatory activity and increased heart rate. A CTA was not established following peripheral GLP-1 administration at any dose tested, though patterns in activity and feeding would suggest that aversion was present at high doses. A dose of 300 nmol/kg GLP-1 increased neuronal activation in several areas important in the acquisition of aversion, including the central nucleus of the amygdala (CeA), nucleus of the solitary tract (NTS) and the mesocorticolimbic system. Activation of brain regions by high doses of PYY and GLP-1 correspond to neuronal activation by administration of LiCl. However, 32 mg/kg LiCl increased activation to a far greater degree, suggesting a distinction between substances that reduce food intake purely by aversion, and those that have endogenous homeostatic functions. The effects of GLP-1 and PYY on appetite and aversion are complex, but likely represent separate systems that are activated differentially by different circulating levels of these hormones. By collaborating with the Mathematical Department, Imperial College London, we hope to develop a mathematical model that distinguishes between specific satiety and aversive behaviours. Further work is now required to determine the utility of such modelling in detecting specific appetite inhibitors and reducing animal use.
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Al, Hinai Eiman Abdulla Mohamed Zahir. "Protein fermentation, gut microbiota and colorectal cancer." Thesis, University of Reading, 2018. http://centaur.reading.ac.uk/81546/.
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The purpose of this project was to determine the interaction between dietary protein and the gut microbiome in the production of genotoxic metabolites, with a particular focus on the poorly characterised metabolite 4-cresol. The thesis describes, in the first instance, data from a large human observation study (n=205 healthy Omani adults). In which dietary records and urinary nitrogen excretion were used to estimate protein consumption in relation to urinary 4-cresol excretion. The study observed positive correlations between excreted 4 cresol and protein intake and then sought to explain the inter-individual variance in this by evaluating the influence of the colonic microbiota. Then the study focused on predicting 4-cresol exposures in the colon using in vitro gut fermentation models. The microbiota composition and metabolic profiles from these models are evaluated against different substrates, including comparisons of animal and plant proteins. We show that the total production of 4-cresol is dependent both on the host microbiota and also upon the dietary nitrogen source. The metabolite profiles of these fermentations may be used to predict DNA damage, with 4-cresol emerging as the greatest correlate of fermentation supernatant mediated genotoxicity. Finally, the study explored whether specific tumour isolates of F. nucleatum produce 4-cresol, or other genotoxins, that could drive intestinal carcinogenesis. At this stage the study is unable to conclude whether or not these isolates are passengers or drivers of intestinal disease. This work suggests the need for better models of the effects of the tumour environment on microbial growth. The most significant aspect of this thesis is that it evidences both the potential genotoxic contribution of 4-cresol in the colonic milieu, but also that urinary 4-cresol sulfate may be used as a biomarker of genotoxic colonic fermentation and thus, may be of use as a cancer risk endpoint in future dietary intervention study.
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Aboim, Catarina Fânzeres de Sousa Pinto. "Gut microbiome in healthy dogs and cats." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2019. http://hdl.handle.net/10400.5/17136.
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Dissertação de Mestrado Integrado em Medicina VeterináriaRecent studies show that the gut microbiome contributes to the vital physiologic and immunologic processes and is influenced by external factors such as diet, environment, medical interventions, and disease states. In this study, we describe the gut microbiome of healthy dogs and cats, from households and shelters, contributing for a better understanding of the effect that environment can have on it. The samples were collected between 2016 and 2017 and consisted of a household group (N=38, N=26 dogs and N=12 cats) and a shelter group (N=62, N=51 dogs and N=11 cats). DNA extraction was done directly from the faeces and the V4 region of the 16S rRNA gene was amplified, followed by sequencing using Illumina MiSeq. Raw sequences were treated using QIIME2 and Greengenes database was chosen for taxonomic classification alignment at 99% similarity. SAS statistical software was used, a p-value < 0.05 was considered. The Principal Coordinate Analysis plot demonstrated that the feline and canine microbiomes were well separated, as well as the household dog samples and the shelter dog samples, meaning that there is a difference in the gut microbiome between these groups. The same conclusion was not observed for the cat samples. The phyla Firmicutes and Bacteroidetes were the predominant ones in both species. For the dog samples, there was no difference between the two groups in Firmicutes and Bacteroidetes phyla (p>0.05), but the phyla Fusobacteria and Proteobacteria were in higher percentages in the shelter group (p<0.05). To our knowledge, this is the first study that describes and compares the gut microbiome composition of healthy household and shelter dogs and cats. This study demonstrates that the environment where animals are born and grow, as well as the amount of contact they have with humans, may have a great influence in their gut microbiome.
RESUMO - Microbioma entérico em cães e gatos saudáveis - Estudos recentes demonstram que o microbioma gastrointestinal tem um papel essencial nos processos fisiológicos e imunológicos do hospedeiro e que é fortemente influenciado pela dieta, ambiente, intervenções médicas e estados de doenças. Neste estudo pretendemos descrever o microbioma entérico de cães e gatos saudáveis provenientes de canis e de casas, contribuindo para uma melhor compreensão do efeito que o ambiente pode ter neste. As amostras foram colhidas entre 2016 e 2017 e consistiam num grupo de casa (N=38, N=26 cães e N=12 gatos) e um grupo de canil (N=62, N=51 cães e N=11 gatos). Foi realizada extração de DNA diretamente a partir das fezes e amplificada a região V4 do gene 16S rRNA, seguindo-se de sequenciação com Illumina MiSeq. As sequências foram tratadas usando o QIIME2 e a biblioteca Greengenes foi escolhida para classificação taxonómica, com o alinhamento a 99% de semelhança. Foi usado o SAS e considerado um p-value<0.05. O Principal Coordinate Analysis plot demonstrou que os microbiomas felino e canino são diferentes, assim como o microbioma de cães de casa e canil. No entanto, não foi possível chegar à mesma conclusão nas amostras de gato. Os phyla Firmicutes e Bacteroidetes foram os predominantes em ambas as espécies sendo que, nas amostras de cão, não houve uma diferença estatisticamente significativa entre os dois grupos para estes phyla (p>0.05). Os phyla Fusobacteria e Proteobacteria foram identificados com maior frequência nas amostras de canil, tendo sido esta diferença estatisticamente significativa (p<0.05). Tanto quanto é do nosso conhecimento, este é o primeiro estudo a descrever e comparar o microbioma gastrointestinal de cães e gatos saudáveis provenientes de casa e canil. Este estudo demonstra que o ambiente em que os animais nascem e habitam, assim como a quantidade de contacto que têm com o ser humano, pode ter grande influência no seu microbioma gastrointestinal.
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Põlajev, Aleksei. "Selfish, mobile genes in honeybee gut bacteria." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-360510.
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Transposons are selfish, mobile genetic elements, moving within the genome. The transposase genemakes this possible, as it codes for the enzyme that catalyzes the movement. In the case of bacteria,they can also move horizontally between individual bacteria, and sometimes even between species.By default, they are a burden for the host organism, coding for a protein that the host does not need.They also pose the risk of disabling the host’s crucial genes by inserting themselves into it.Transposons are under some pressure to benefit the host, to help propagate themselves moreeffectively. And some transposons have indeed evolved to benefit the host. Lactobacillus kunkeei is a bacterial species known to reside in honeybee guts. It is known for itsrole in honey preservation and wine spoilage. The genome of L. kunkeei is reduced because it is asymbiont, however it contains an unusually high amount of transposons in its genome. In this study, the transposase genes (transposon enzymes) found in L. kunkeei are studied andcategorized. The L. kunkeei have been extracted from honeybees (Apis mellifera). The honeybeesthemselves have been collected from the islands Åland and Gotland. This study focuses on the transposase genes that come in pairs, one after another in the genome.Transposase genes were identified using annotation software and orthology-based methods. Theannotation software provides numbering for the genes, which allows finding paired genes. Thepaired genes were categorized based on alignments and phylogenetic software. Pseudogenizedtransposons were identified based on length and/or clustering into triplets. A total of 766 paired transposase genes were found. The transposase genes were found to take up1.9% of the genome, on average. A low level of diversity has been found when performingalignments and generating phylogenetic trees. The positions of the transposase genes are generallyconserved within phylogenetic groups. Pseudogenization has been detected for some transposasegenes – 4.5 per genome, on average. All of the studied transposons belong to the IS3 family, whichis a family of Class I transposons.
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MacNeill, Morgan T. "Strawberries and Gut Health in Postmenopausal Women." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2072.
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The gut microbiota has been implicated in both health and disease. As such, diet is a significant determinant of gut health, whereby diet induced dysbiosis is associated with cardiometabolic risk. Interestingly, a higher proportion of Firmicutes and a lower proportion of Bacteroidetes are implicated in obesity. Strawberry polyphenols have been shown to reduce cardiovascular disease risk in addition to exhibiting prebiotic activity by increasing probiotic bacteria in the gut. Polyphenols have also been shown to reduce the ratio of Firmicutes to Bacteroidetes. Therefore, dietary modifications such as strawberry consumption may help improve health outcomes through the gut. The objective of this study was to analyze whether 13 g freeze dried strawberry powder (~1 cup/d fresh) consumption reduces the Firmicutes:Bacteroidetes ratio and increases microbial diversity and beneficial bacteria like Lactobacillus and Bifidobacterium. This study was a 5-week free-living diet intervention trial conducted at California Polytechnic State University, San Luis Obispo with expansion to the Eye Medical Center of Fresno. Participants (n=10) had a mean age of 60.5 ± 9.13 years and had a mean body weight of 74.71 ± 10.61 kg. The participants completed a 3-week washout before a 2-week diet intervention. Participants maintained their normal diet throughout the study while eliminating foods high in polyphenols and probiotics. Upon completion of the study, no significant differences were found for body weight (p=0.22) or BMI (p=0.26). Likewise, no significant differences were found for macronutrient, vitamin, or mineral intake except for sugar (p=0.03), vitamin B12 (p=0.03), and fruit (p=0.0014). Bacteria abundance and diversity were not found to be statistically significant following intervention. Since strawberry supplementation was not associated with a significant change in the relative abundance of bacteria with the dose and duration administered, a randomized controlled trial would better determine the effect of strawberry consumption on gut health.