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Role of the gastrointestinal tract in postprandial blood pressure regulationGentilcore, Diana January 2006 (has links)
This thesis presents studies relating to the role of the gastrointestinal tract in postprandial blood pressure regulation. The areas that have been addressed include : ( i ) the methodological approaches to the evaluation of gastric emptying, blood pressure, splanchnic blood flow, intraluminal manometry and gut hormones and ( ii ) the pathophysiological mechanisms underlying postprandial hypotension, with a particular focus on ' gastric ' and ' small intestinal ' mechanisms and their potential therapeutic relevance. All of the studies have been either published or manuscripts have been prepared for publication. While scintigraphy represents the ' gold standard ' for the measurement of gastric emptying, recent studies suggest that three - dimensional ( 3D ) ultrasonography may also allow a precise measure of gastric emptying. Concurrent scintigraphic and ultrasonographic measurements of gastric emptying of liquids were performed in healthy young volunteers. There was a good correlation and agreement between scintigraphic measurements of gastric emptying and 3D ultrasonography after ingestion of both low - and high - nutrient drinks, indicating that 3D ultrasonography, provides a valid measure of gastric emptying of liquid meals in normal subjects. Postprandial hypotension, defined as a fall in systolic blood pressure of ≥ 20mmHg,occurring within two hours of a meal is now recognised as an important clinical problem, particularly in the elderly and in patients with type 2 diabetes. The mechanisms mediating postprandial hypotension are poorly understood. The effects of variations in concentration of intraduodenal glucose on the magnitude of the fall in blood pressure were evaluated in healthy elderly subjects. Blood pressure fell, and heart rate and blood glucose increased over time during infusions, however, there was no difference in blood pressure, heart rate or blood glucose concentrations between the study days. These observations suggest that glucose induced postprandial hypotension is a load rather, than concentration, dependent phenomenon. The effect of meal composition has been reported to influence the hypotensive response to a meal and information relating to the effects of triglyceride and protein on blood pressure is inconsistent. The comparative effects of isocaloric and isovolaemic intraduodenal infusions of glucose, triglyceride and protein on the magnitude of the postprandial fall in blood pressure and rise in heart rate and superior mesenteric artery blood flow were evaluated in healthy elderly subjects. There were comparable falls in systolic blood pressure and rises in heart rate, however, the maximum fall in systolic blood pressure occurred later after triglyceride and protein and the stimulation of superior mesenteric artery blood flow was less after protein. These observations suggest that the relatively slower systolic blood pressure response after triglyceride and protein may potentially reflect the time taken for digestion of triglyceride to free fatty acids and protein to amino acids. Acarbose is an antidiabetic drug that slows both gastric emptying and small intestinal glucose absorption. The effects of acarbose, on blood pressure, heart rate, gastric emptying of, and the glycaemic, insulin, glucagon - like peptide - 1 ( GLP - 1 ) and glucosedependent insulinotropic - polypeptide ( GIP ) responses to, an oral sucrose load were evaluated in healthy elderly subjects. Acarbose attenuated the fall in blood pressure and increase in heart rate induced by oral sucrose. Acarbose slowed gastric emptying and was associated with increased retention in the distal stomach. Stimulation of GLP - 1 may contribute to the slowing of gastric emptying and suppression of postprandial glycaemia by acarbose. These findings suggest that acarbose may represent a therapeutic option for the treatment of patients with postprandial hypotension. Recent studies indicate that gastric distension attenuates the postprandial fall in blood pressure. The effects of gastric distension on blood pressure and heart rate during intraduodenal infusion of glucose at a constant load and concentration were evaluated in healthy elderly subjects. Intragastric administration of water markedly attenuated the falls in systolic and diastolic blood pressure induced by intraduodenal glucose. Heart rate increased, with and without gastric distension, in response to intraduodenal glucose infusion but not after intraduodenal saline infusion. This study suggests that gastric distension may potentially be used as a simple adjunctive treatment in the management of postprandial hypotension. Studies employing nitric oxide synthase blockers have established, in animals, that nitric oxide mechanisms are important in the regulation of splanchnic blood flow and, hence, may effect postprandial blood pressure. The role of the nitric oxide synthase inhibitor, NG - nitro - L - arginine - methyl - ester ( L - NAME ), on gastric emptying, postprandial blood pressure, plasma insulin concentration and incretin hormone ( ie GIP and GLP - 1 ) release, following an oral glucose load, were evaluated in healthy elderly subjects. L - NAME attenuated the postprandial fall in blood pressure and increase in heart rate but had no effect on gastric emptying of glucose. L - NAME attenuated the glucose - induced rise in plasma insulin but had no effect on the incretin ( GIP and GLP - 1 ) hormone response to oral glucose. The study indicates that the magnitude of the fall in blood pressure and increase in heart rate and stimulation of insulin secretion induced by oral glucose in healthy elderly subjects are mediated by nitric oxide mechanisms by an effect unrelated to changes in gastric emptying, or the secretion of GIP and GLP - 1. Studies utilising 5 - hydroxytryptamine ( 5 - HT ) infusions in animals have demonstrated regional variations in intestinal blood flow suggesting a role for 5 - HT in postprandial haemodynamic responses. The effects of the 5 - hydroxytryptamine 3 ( 5 - HT3 ) antagonist, granisetron, on the blood pressure, heart rate, antropyloroduodenal motility and glycaemic responses to intraduodenal glucose infusion were assessed in healthy elderly subjects. Granisetron had no effect on blood pressure, heart rate or antral and pyloric motor responses but modulated the duodenal motor response, to intraduodenal glucose. This study indicates that while the cardiovascular response to intraduodenal glucose does not appear to be influenced by the stimulation of 5 - HT3 receptors, this receptor may be involved in the modulation of the duodenal motor activity. / Thesis (Ph.D.)--School of Medicine, 2006.
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Expression of genes encoding bacteriocin ST4SA as well as stress proteins by Enterococcus mundtii ST4SA exposed to gastro-intestinal conditions, as recorded by real-time polymerase chain reaction (PCR)Granger, Monique 03 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The tolerance of Enterococcus mundtii ST4SA to stressful gastro-intestinal conditions in
humans and animals is vital to its success as a probiotic. The need for new effective
probiotics with stronger inhibitory (bacteriocin) activity has arisen due to the increasing
number of antibiotic resistant pathogens. Enterococci are used in the fermentation of
sausages and olives, cheese making and as probiotics. Their role as opportunistic
pathogens in humans makes them a controversial probiotic (Moreno et al., 2005).
Enterococci occur naturally in the gastro-intestinal tract which renders them intrinsic acid
and bile resistance characteristics. E. mundtii ST4SA produces a 3950 Da broad-spectrum
antibacterial peptide active against Gram-positive and Gram-negative bacteria, and
viruses. The bacteria include Enterococcus faecalis, Streptococcus spp., Pseudomonas
aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae and Staphylococcus
aureus. E. mundtii ST4SA inactivates the herpes simplex viruses HSV-1 (strain F) and
HSV-2 (strain G), a measles virus (strain MV/BRAZIL/001/91, an attenuated strain of
MV), and a polio virus (PV3, strain Sabin).
This study focuses on the genetic stability of E. mundtii ST4SA genes when exposed to
stress factors in the human and animal gastrointestinal tract. Based on results obtained by
real-time PCR, the expression of genes encoding bacST4SA, RecA, GroES and 23S
rRNA by E. mundtii ST4SA were not affected when the cells were exposed to acid, bile
and pancreatic juice. This suggests that these genes of E. mundtii ST4SA will remain
stable in the intestine. This could indicate that other genes of E. mundtii ST4SA could
remain stable in the host. Further studies on the stability of genes encoding antibiotic
resistance and virulence factors should be conducted to determine their stability and
expression in the host in stress conditions. Concluded from this study, E. mundtii ST4SA
is an excellent probiotic strain. / AFRIKAANSE OPSOMMING: Enterococcus mundtii ST4SA se weerstandsvermoë teen stresvolle gastrointestinale
kondisies is essensieel vir die sukses van hierdie organisme as ‘n probiotikum. Die
aanvraag vir nuwe, meer effektiewe probiotika met sterker inhibitoriese (bakteriosien)
aktiwiteit is as gevolg van die toename in antibiotikum weerstandbiedende patogene.
Enterococci word algemeen gebruik as probiotika, sowel as in die fermentasie van worse,
olywe en kaas. Hulle rol as oppertunistiese patogene in mense veroorsaak kontroversie as
gevolg van hul toenemende gebruik as probiotika. Enterococci is deel van die natuurlike
mikroflora in die gastrointestinale weg van mense en diere. Dit verleen aan hierdie
spesies ‘n natuurlike weerstandsvermoë teen maagsure, galsoute en pankreatiese
afskeidings. E. mundtii ST4SA produseer ‘n 3950 Da wye spektrum anti-bakteriese
peptied, aktief teen Gram positiewe en Gram negatiewe bakterieë sowel as virusse.
Hierdie bakterieë sluit Enterococcus faecalis, Streptococcus spp., Pseudomonas
aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae en Staphylococcus
aureus in. E. mundtii ST4SA inaktiveer die herpes simpleks virus HSV-1 en HSV-2, ‘n
masels virus (MV/BRAZIL/001/91), en ‘n polio virus (PV3, stam Sabin).
Hierdie studie fokus op die genetiese stabiliteit van E. mundtii ST4SA gene, wanneer
hulle blootgestel word aan stress faktore in die mens en dier gastrointestinale weg.
“Intydse” PKR data gebasseer op die uitdrukking van die bacST4SA, RecA, GroES en
23S rRNA gene in stresvolle kondisies dui aan dat E. mundtii ST4SA nie geaffekteer
word wanneer die sel blootgestel word aan suur, gal en pankreatiese vloeistowwe nie.
Hierdie resultate dui aan dat hierdie gene van E. mundtii ST4SA stabiel sal bly in die
intestinale weg van die mens en dier. Dit kan aandui dat ander gene van E. mundtii
ST4SA soos die wat kodeer vir virulensie faktore en antibiotikum se weerstandsvermoë
stabiel mag bly in die gasheer. Verdere studies wat fokus op die stabiliteit van gene wat
kodeer vir antibiotikum weerstandbiedendheid en virulensie faktore moet uitgevoer word
om hulle stabiliteit en uitdrukking in die gasheer te bepaal. Bevindings van hierdie studie
dui aan dat E. mundtii ST4SA goeie potensiaal het as ‘n probiotikum.
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Gastro-duodenal motility & nutrition in the critically ill.Chapman, Marianne January 2008 (has links)
Inadequate delivery of nutrition to the critically ill is common, and may adversely affect clinical outcomes, including survival. This thesis reports studies designed to characterise the gastrointestinal dysfunction underlying feed intolerance in the critically ill, as well as the pathophysiology of these dysfunctions, and investigate potential therapeutic measures. While it has been established that enteral nutrition is frequently unsuccessful in the critically ill, assessment of the success of feeding in an Australian intensive care unit (ICU) had not been performed previously. A prospective survey examined the incidence of, and risk factors for, feed intolerance in the ICU at the Royal Adelaide Hospital and demonstrated that, in 40 patients receiving enteral feeding, only about 60% of their nutritional requirements were met at the end of the first week. The main cause for this lack of success was large gastric residual volumes, indicative of delayed gastric emptying (GE). This study, accordingly, quantified the limitations of nutritional delivery in contemporary practice in a local ICU. The results suggest that a better understanding of the pathogenesis underlying this problem is warranted in order to direct research into improved therapies. Scintigraphy is the most accurate technique to measure GE, but is difficult to perform in the ICU. A simpler, more convenient, test would increase the accessibility of GE measurement for both research and clinical purposes. A study comparing a breath test technique and gastric residual volume measurement to the scintigraphic measurement of GE in 25 mechanically ventilated patients demonstrated that GE measured by a breath test technique closely correlated with that measured by scintigraphy. While the breath test had a specificity of 100% it only had a sensitivity of about 60% in the prediction of delayed GE. Similarly, gastric residual volume measurement correlated with scintigraphic measurement of GE but also lacked sensitivity. The breath test has previously been demonstrated to be highly reproducible and it represents a useful option for repeated measurement of GE in the same patient. It is therefore likely to be useful to determine changes in GE over time or in response to a therapeutic intervention. There is a lack of information about the prevalence and determinants of delayed GE in the critically ill. Previous studies have substantial limitations and scintigraphic measurement of GE has only rarely been used. A study comparing GE measured by scintigraphy in 25 patients to 14 healthy subjects demonstrated that GE was delayed in approximately 50% of the ICU patients (>10% retention at 4h) and markedly delayed in about 20% (>50% retention at 4h). Patients with trauma and sepsis appeared to have a relatively higher prevalence of delayed GE (80% and 75% respectively). In addition, the longer the patient had been in ICU the more normal the rate of GE. Quantification of delayed GE may prove useful by defining patients who may benefit from preventative or therapeutic options. The abnormalities in gastrointestinal motility underlying delayed GE in the critically ill are poorly characterised. Simultaneous manometric and gastric emptying measurements were performed in 15 mechanically ventilated patients and 10 healthy subjects. These studies demonstrated that delayed GE was associated with reduced antral activity, increased pyloric activity and increased retrograde duodenal activity in the patients. Persistent fasting motility during feeding was also frequently observed. Furthermore, the feedback response to small intestinal nutrients was enhanced. This latter observation may provide an explanation for the delayed GE and warrants further investigation. Recent studies suggest that the hormone cholecystokinin may be a mediator of increased small intestinal feedback and, if confirmed, this has clear therapeutic implications. Nutrient absorption has rarely been measured in the critically ill. GE and glucose absorption (using 3-O-methyl glucose) were measured simultaneously in 19 ICU patients and compared to 19 healthy subjects. Glucose absorption was shown to be markedly reduced in the patients. Slow GE was associated with delayed, and reduced, absorption. However, glucose absorption was also reduced in patients with normal GE suggesting that reduced glucose absorption in critical illness is only partly due to delayed GE. Accordingly, measures to improve the effectiveness of GE and thereby improve overall nutritional status may be compromised by abnormal small intestinal absorption. The mechanisms underlying this warrant further investigation. A number of therapeutic options directed at improving the delivery of nutrition were examined. In a study involving 20 mechanically ventilated patients, administration of 200mg erythromycin intravenously was shown to be superior to placebo for treating feed intolerance. The optimal dose of erythromycin, however, was unclear. In a subsequent study involving 35 ICU patients, GE was measured using a breath test technique, before and after 2 different doses of erythromycin or placebo and a ‘low’ intravenous dose (70mg) of erythromycin appeared to be as effective as a ‘moderate’ dose (200mg). Both doses were only effective in subjects who had delayed GE at baseline. Based on the outcome of these studies, low doses of erythromycin have subsequently been routinely used to treat feed intolerance in the critically ill patients at the Royal Adelaide Hospital. Animal and human studies suggested that the antibiotic, cefazolin, may have a prokinetic effect. Cefazolin, however, did not demonstrate similar prokinetic activity at a ‘low’ dose (50mg) in a critically ill cohort. The results of this study do not support the use of this agent, at this dose, as a prokinetic, in this population. If nasogastric administration of nutrition proves unsuccessful an alternative is to infuse nutrient directly into the small intestine. However, the placement of feeding tubes distal to the pylorus is technically difficult. A novel technique for postpyloric tube insertion was examined with promising results. In summary, the studies described in this thesis have provided a number of insights relevant to the management of the critically ill by quantifying the prevalence of feed intolerance and delayed GE, characterising some of the disturbances in gastrointestinal motility underlying this problem, and evaluating a number of therapeutic interventions. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1345143 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2008
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Gastro-duodenal motility & nutrition in the critically ill.Chapman, Marianne January 2008 (has links)
Inadequate delivery of nutrition to the critically ill is common, and may adversely affect clinical outcomes, including survival. This thesis reports studies designed to characterise the gastrointestinal dysfunction underlying feed intolerance in the critically ill, as well as the pathophysiology of these dysfunctions, and investigate potential therapeutic measures. While it has been established that enteral nutrition is frequently unsuccessful in the critically ill, assessment of the success of feeding in an Australian intensive care unit (ICU) had not been performed previously. A prospective survey examined the incidence of, and risk factors for, feed intolerance in the ICU at the Royal Adelaide Hospital and demonstrated that, in 40 patients receiving enteral feeding, only about 60% of their nutritional requirements were met at the end of the first week. The main cause for this lack of success was large gastric residual volumes, indicative of delayed gastric emptying (GE). This study, accordingly, quantified the limitations of nutritional delivery in contemporary practice in a local ICU. The results suggest that a better understanding of the pathogenesis underlying this problem is warranted in order to direct research into improved therapies. Scintigraphy is the most accurate technique to measure GE, but is difficult to perform in the ICU. A simpler, more convenient, test would increase the accessibility of GE measurement for both research and clinical purposes. A study comparing a breath test technique and gastric residual volume measurement to the scintigraphic measurement of GE in 25 mechanically ventilated patients demonstrated that GE measured by a breath test technique closely correlated with that measured by scintigraphy. While the breath test had a specificity of 100% it only had a sensitivity of about 60% in the prediction of delayed GE. Similarly, gastric residual volume measurement correlated with scintigraphic measurement of GE but also lacked sensitivity. The breath test has previously been demonstrated to be highly reproducible and it represents a useful option for repeated measurement of GE in the same patient. It is therefore likely to be useful to determine changes in GE over time or in response to a therapeutic intervention. There is a lack of information about the prevalence and determinants of delayed GE in the critically ill. Previous studies have substantial limitations and scintigraphic measurement of GE has only rarely been used. A study comparing GE measured by scintigraphy in 25 patients to 14 healthy subjects demonstrated that GE was delayed in approximately 50% of the ICU patients (>10% retention at 4h) and markedly delayed in about 20% (>50% retention at 4h). Patients with trauma and sepsis appeared to have a relatively higher prevalence of delayed GE (80% and 75% respectively). In addition, the longer the patient had been in ICU the more normal the rate of GE. Quantification of delayed GE may prove useful by defining patients who may benefit from preventative or therapeutic options. The abnormalities in gastrointestinal motility underlying delayed GE in the critically ill are poorly characterised. Simultaneous manometric and gastric emptying measurements were performed in 15 mechanically ventilated patients and 10 healthy subjects. These studies demonstrated that delayed GE was associated with reduced antral activity, increased pyloric activity and increased retrograde duodenal activity in the patients. Persistent fasting motility during feeding was also frequently observed. Furthermore, the feedback response to small intestinal nutrients was enhanced. This latter observation may provide an explanation for the delayed GE and warrants further investigation. Recent studies suggest that the hormone cholecystokinin may be a mediator of increased small intestinal feedback and, if confirmed, this has clear therapeutic implications. Nutrient absorption has rarely been measured in the critically ill. GE and glucose absorption (using 3-O-methyl glucose) were measured simultaneously in 19 ICU patients and compared to 19 healthy subjects. Glucose absorption was shown to be markedly reduced in the patients. Slow GE was associated with delayed, and reduced, absorption. However, glucose absorption was also reduced in patients with normal GE suggesting that reduced glucose absorption in critical illness is only partly due to delayed GE. Accordingly, measures to improve the effectiveness of GE and thereby improve overall nutritional status may be compromised by abnormal small intestinal absorption. The mechanisms underlying this warrant further investigation. A number of therapeutic options directed at improving the delivery of nutrition were examined. In a study involving 20 mechanically ventilated patients, administration of 200mg erythromycin intravenously was shown to be superior to placebo for treating feed intolerance. The optimal dose of erythromycin, however, was unclear. In a subsequent study involving 35 ICU patients, GE was measured using a breath test technique, before and after 2 different doses of erythromycin or placebo and a ‘low’ intravenous dose (70mg) of erythromycin appeared to be as effective as a ‘moderate’ dose (200mg). Both doses were only effective in subjects who had delayed GE at baseline. Based on the outcome of these studies, low doses of erythromycin have subsequently been routinely used to treat feed intolerance in the critically ill patients at the Royal Adelaide Hospital. Animal and human studies suggested that the antibiotic, cefazolin, may have a prokinetic effect. Cefazolin, however, did not demonstrate similar prokinetic activity at a ‘low’ dose (50mg) in a critically ill cohort. The results of this study do not support the use of this agent, at this dose, as a prokinetic, in this population. If nasogastric administration of nutrition proves unsuccessful an alternative is to infuse nutrient directly into the small intestine. However, the placement of feeding tubes distal to the pylorus is technically difficult. A novel technique for postpyloric tube insertion was examined with promising results. In summary, the studies described in this thesis have provided a number of insights relevant to the management of the critically ill by quantifying the prevalence of feed intolerance and delayed GE, characterising some of the disturbances in gastrointestinal motility underlying this problem, and evaluating a number of therapeutic interventions. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1345143 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2008
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Identification and validation of new markers and potential therapeutic targets for gastrointestinal stromal tumors in murine models and in human pathological materialGromova, Petra 09 June 2011 (has links)
Les tumeurs gastro-intestinales stromales (Gastro-Intestinal Stromal Tumours - GIST en Anglais) sont les sarcomes les plus fréquents du tube digestif. Sur base de leur profil d'expression génique et de similitudes morphologiques, il a été établi que les GIST dérivent des cellules interstitielles de Cajal (Interstitial Cells of Cajal - ICC en Anglais) ou d'un précurseur commun. Le développement et le maintient des ICC sont dépendant de voies de signalisation du récepteur tyrosine kinase KIT. Des mutations oncogéniques de KIT, conduisant indépendamment du ligand à l'activation des voies de signalisation en aval, sont présentes dans environ 85% des GIST. Depuis une dizaine d'années, des molécules de synthèse qui inhibent la phosphorylation -et donc l'activation - de KIT ont été introduites avec succès dans le traitement clinique des GIST. Cependant des résistances, souvent causées par des mutations secondaires, apparaissent fréquemment et environ 50% des patients traités rechutent dans les 2 ans. Le développement de nouvelles stratégies diagnostiques et thérapeutiques pour les GIST demeure donc essentiel. Ces dernières années, de nouveaux marqueurs diagnostiques ou cibles thérapeutiques potentielles ont été rapportés dans la littérature (p.ex. Discovered on GIST-1 (DOG1, anoctamin 1), Protein kinase C theta (PKC theta), Carbonic anhydrase II (CAII)) .Il faut relever que tous ces gènes sont aussi exprimés par les ICC KIT+ du tube digestif normal et que leur présence dans les GIST reflète donc vraissemblablement essentiellement leur parenté avec les ICC.<p>Dans la présente étude, nous nous sommes attachés à identifier de nouveaux marqueurs diagnostiques ou cibles thérapeutiques potentielles exprimés par les GIST mais absent des ICC KIT+ normales.<p>Pour ce faire, nous avons comparé le profile d'expression géniques de l'antre gastrique de souris porteuses de la mutation oncogénique Kit K641E et de souris contrôles (wild type WT en Anglais) par la technique de cDNA microarray. Les différences d'expression génique ont été ensuite confirmées par réactions de PCR quantitative (qPCR) en temps réel et l'immunoréactivité (-ir) pour les candidats les plus prometteurs a été localisée par immunofluorescence (IF) dans la muscularis propria du tube digestif, avec une attention spéciale pour les cellules KIT+.<p>Plusieurs gènes identifiés appartenaient tant au profil d'expression génique des GIST qu'au profil d'expression des ICC Kit+ de l'intestin grêle murin, validant ainsi la pertinence du modèle murin KitK641E pour l'approche choisie (Chapitre 3). D'autre part, trois gènes identifiés (Neurotensin receptor 1 (Ntsr1), Trophoblast glycoprotein (Tpbg/5T) et Sprouty homolog 4 (Spry4)) étaient quant à eux présents dans la couche hypertrophié de cellules Kit+ de l'antre des souris KitK641E mais absentes des ICC Kit+ chez les souris WT (Chapitres 3, 4, 5). Ces gènes représentant donc de nouveaux candidats potentiels comme marqueurs spécifiques et/ou comme cibles thérapeutiques dans les GIST, nous avons, dans la seconde partie de notre travail, approfondi l'étude de leur expression et de leur régulation en utilisant des modèles cellulaires et tissulaires murins, ainsi que du matériel anatomopathologique de GIST humains.<p>Dans le tube digestif normal, NTSR1 et TPBG/5T4 ir ont été identifiés dans les neurones myentériques mais pas dans les ICCKIT+. Deux "tissue arrays" indépendants, totalisants 97 spécimens humains de GIST, ont révélés la présence de NTSR1-ir dans tous les GIST, en ce compris les cas négatifs pour KIT, tandis que TPBG/5T4-ir était présente dans 36/49 GIST. Un fort immunomarquage pour TPBG/5T4 était statistiquement associée aux tumeurs malignes et de haut risque (Chapitre 5; Annexe 1).<p>L'expression différentielle de membres de la famille des "Sprouty homologues" (Spry) dans l'antre des souris KitK641E a aussi été identifiée. Spry4-ir n'était pas détectable dans les ICC KIT+ des souris WT alors que Spry4-ir était présente dans la couche hyperplasique des cellules Kit+ chez les souris KitK641E. A l'opposé, l'ARN messager de Spry2 présentait un niveau d'expression similaire et Spry2-ir était détectée dans les cellules musculaires lisses - mais pas dans les cellules Kit+ - dans tous les génotypes (Chapitre 3). Pour sa part, l'expression de Spry1 apparaissait réprimée par le mutant oncogénique KitK641E, tant in vivo qu'in vitro, conduisant à la dérégulation de la boucle de rétrocontrôle négatif de la voie Ras/Erk (Chapitre 4). <p>Dans la dernière partie de cette thèse, nous avons étudié l'expression Endoglin (ENG) - aussi connues sous le nom de CD105 – dans le modèle murin de GIST KitK641E, dans les GIST humains et dans le modèle cellulaire murin Ba/F3 in vitro. ENG est une glycoprotéine transmembraire et un composant auxiliaire du complexe du récepteur au TGF-& / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished
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Nucleotide sequence variation and expression levels of TP53 in cancers of the upper gastro-intestinal tractBarnard, Desire 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The work presented in this thesis deals with the association between cancers of
the upper gastro-intestinal tract and the tumor suppressor gene, TP53, and can
be divided into three parts: (i) the analysis of the mutational spectrum of TP53
with respect to laryngeal cancer, (ii) the analysis of the mutational spectrum of
TP53 with respect to esophageal cancer and (iii) the analysis of TP53
transcriptional levels in esophageal cancer.
Laryngeal cancer (LC) is the 6th most common cancer in the world and the 2nd
most common respiratory cancer, with approximately 500 000 new cases per
annum detected worldwide. Over the last few years, LC has become
increasingly prevalent within the Coloured Community of the Western Cape. The
mechanisms of tumorigenesis in LC remain unknown, although smoking and
alcohol consumption are considered to be major risk factors. Mutations within
the gene TP53 have been strongly implicated as playing a role in cancer
development, as they are frequently found in several cancer types. We therefore
screened exons 5 - 8 of TP53 for mutations in DNA from tumor biopsies (n=44)
and blood samples (n=42) from Coloured LC patients, using polymerase chain
reaction - single strand conformation polymorphism (PCR-SSCP) analysis and
direct sequencing. Blood samples from a healthy, matched control group (n=40)
were included in the study as controls. Significant correlations were found
between the occurrence of LC and age and smoking, whereas daily meat
consumption was a possible protective factor. In tumor-derived samples,
mutations were found in 3 of the exons under investigation, representing 25% of
the samples. The mutations were unique to the tumor biopsies, indicating a
somatic origin for mutations. The data confirms that the region between codons
175 and 273 of TP53 is a mutational hotspot for cancers in general. This study
reports 6 novel mutations within this same region. Esophageal cancer (EC) has a very high incidence in South Africa, relative to the
rest of the world, and is particularly common amongst the Black Transkei
population. The goal of this study was to determine whether there are
differences in the TP53 mutational pattern observed in the Coloured Western
Cape community as compared to that observed in the Black Transkei community.
This required the analysis of the molecular structure of TP53, specifically exons 5
- 8, in a group of Coloured EC patients (n=44) treated at Tygerberg Hospital,
Cape Town, South Africa. DNA obtained from tumor biopsies and blood (from
patients) as well as from apparently healthy surrounding tissue was screened via
PCR-SSCP and direct sequencing analysis. Only 4 nucleotide changes were
observed from a total of 124 sequences obtained, of which two were novel to
esophageal squamous cell carcinoma. These 4 nucleotide alterations were
found only within the tumor biopsy sample set, representing 9% of the tumors
investigated. This study revealed that the mutational spectrum of TP53 within
the Coloured population of the Western Cape greatly differs from that of the
Black community of the Transkei. This suggests that a different set of etiological
factors are involved in the tumorigenic process for each of these distinct
geographical communities, which is the subject of an epidemiological study
undertaken by the MRC.
The final part of this thesis deals with the quantification and comparison of TP53
transcription levels in esophageal cancer tumor tissue to the TP53 levels in
healthy esophageal tissue obtained from patients from a unique geographical
and ethnic background. The cohort used in this study consisted of Coloured
patients (n=2) treated at Tygerberg Hospital. The LightCycler system was
implemented in order to try to accurately quantify TP53 mRNA levels.
Unfortunately, the desired results were unattainable due to unforeseen difficulties
encountered during the study. These difficulties included the insufficient
preservation of samples for RNA based studies. Several recommendations were
made concerning future similar studies, including an improved planning strategy
as well as the employment of an RNA stabilizing agent. Additionally, a few important contributions were made through this study, including the design and
optimization of TP53 primers specifically intended for future RNA studies. These
primers would enable the identification of the presence of TP53 RNA species as
well as the absence of DNA contamination in a single PCR amplification step.
Other contributions include the development of a well-optimized RNA extraction
method for the extraction of RNA from tough tissues (such as the human
esophageal tissue used in this study). This method makes the extraction of large
quantities of RNA from small amounts of tough tissue types possible.
In conclusion, this study has made a significant contribution to the field of cancer
research, by shedding light on the TP53 mutational spectrum with regards to
laryngeal as well as esophageal cancer in a population unique to the Western
Cape.
The first part of this thesis has been published in Cancer Genetics and
Cytogenetics (Barnard, D., K. Lehmann, E.G. Haal, P.O. van Heiden, and l.C.
Victor. 2003. The spectrum of mutations in TP53 in laryngeal cancer patients
from a high-incidence population shows similarities to many of the known
mutational hotspots. Cancer Genetics and Cytogenetics 145:126-132), of which
a copy can be found in Appendix I. This work has also been presented (by D.
Barnard) at an international conference entitled "Cancer of the Esophagus and
Gastric Cardia: From Gene to Cure", held in Amsterdam, the Netherlands during
the period 13 - 15 December 2002. / AFRIKAANSE OPSOMMING: Die werk wat in hierdie tesis voorgelê word handel oor die assosiasie tussen
kankers van die boonste gastrointestinale weg en die tumor suppressor geen,
TP53, en kan in 3 dele gedeel word, (i) die analise van die mutasiespektrum van
TP53 in laringiale kanker (LK), (ii) die analise van die mutasiespektrum van TP53
in slukderm kanker (SK) en (iii) die analise van die transkripsievlakke van TP53
in SK.
Laringeal kanker (LK) is die 6de algemeenste kanker in die wêreld en die 2de
algemeenste respiratoriese kanker, met "n benaderde 500 000 nuwe gevalle
jaarliks wêreldwyd. Oor die afgelope paar jare het LK "n toenemende probleem
geraak, veral in die Kleurling gemeenskap van die Wes Kaap. Die meganismes
van die tumorvorming in LK is onbekend, alhoewel rook-en alkoholgebruik
vername risiko faktore is. Die voorkoms van mutasies in TP53 is verskeie kere
aangetoon in verskillende kanker tipes en daar word vermoed dat dit "n rol speel
in tumorvorming. In hierdie studie is dus na mutasies in eksons 5 - 8 van TP53
gesoek in tumor biopsie weefsel (n=44) en bloed isolate (n=42) van Kleurling LK
pasiënte d.m.v. polimerase ketting reaksie - enkelstring konformasie
polimorfisme (PKR-ESKP) analisering en direkte volgorde bepaling. Bloed
monsters van "n vergelykbare groep (n=40) is ook in die studie ingesluit as "n
kontrole. Betekenisvolle positiewe korrelasies is gevind tussen die voorkoms van
LK en ouderdom sowel as rook. Daarmee saam is daaglikse vleisinname as
potensiële beskermende faktor gevind. In tumor biopsies is mutasies in 3 van
die ondersoekte eksons gevind, wat 25% van die biopsie monsters
verteenwoordig. Hierdie mutasies is uniek aan die tumor biopsie weefsels en dui
op "n somatiese oorsprong van mutasies. Hierdie bevindinge bevestig dat die
gedeelte tussen kodons 173 - 273 van TP53 "n hipermuteerbare gebied
geassosieer met kankers is. Hierdie studie bevestig 6 nuwe mutasies.
Daar is 'n hoë insidensie van slukderm kanker (SK) in Suid Afrika relatief tot die
res van die wêreld. Hierdie soort kanker word veral gevind by die Swart
populasie van die Transkei. Die doel van hierdie studie was om verskille tussen
die TP53 mutasie patroon van die Kleurling gemeenskap van die Wes Kaap en
die Swart gemeenskap van die Transkei te vergelyk. Hiervoor is die molekulêre
struktuur van TP53, veral eksons 5 - 8, in 'n groep Kleurling SK pasiënte (n=42)
wat behandel is by Tygerberg Hospitaal, Kaapstad, Suid Afrika, geanaliseer.
Analisering is gedoen deur DNS van tumor, bloed en ook oënskynlike gesonde
aangrensende weefsel van dieselfde pasiënte te onderwerp aan PKR-ESKP
analise en direkte volgorde bepaling. Slegs 4 nukleotied veranderings is gevind
in 124 volgorde bepalings, waarvan 2 nuwe veranderings is in SK. Hierdie 4
nukleotied veranderinge verteenwoordig 9% van al die tumors wat ondersoek is
in die studie. Hierdie studie bewys dat die mutasiespektrum van TP53 in die
Kleurling gemeenskap van die Wes Kaap grootliks verskil van die Swart
gemeenskap van die Transkei. Dit impliseer dat verskillende etiologiese faktore
moontlik 'n rol mag speel op die tumorvormingsproses in die 2 afsonderlike
geografiese gemeenskappe. Hierdie is die onderwerp van 'n epidemiologiese
studie wat deur die MNR onderneem word.
Die laaste deel van hierdie tesis handel oor die kwantifisering en vergelyking van
TP53 transkripsievlakke in SK tumor weefsel teenoor TP53 vlakke in gesonde
slukderm weefsel van pasiënte in 'n unieke geografiese en etniese agtergrond.
Die studie populasie in hierdie projek het bestaan uit Kleurling pasiënte (n=2) wat
by Tygerberg hospitaal behandel is. Die "LightCycler" sisteem is gebruik vir die
akkurate kwantifisering van TP53 boodskapper RNS vlakke. Ongelukkig is die
verlangde resultate nie gekry nie as gevolg van onvoorsiene probleme wat
ondervind is tydens die studie. Hierdie probleme sluit in die onvoldoende
preserv RNS studies. Hierdie inleiers maak dit nou moontlik om die teenwoordigheid van
TP53 RNS spesies sowel as die afwesigheid van DNS kontaminasie in een PKR
amplifikasie stap te kan identifiseer. 'n Ander belangrike bydrae is die
ontwikkeling van 'n goed geoptimaliseerde RNS ekstraksie metode vir moeilike
starre weelfsel tipes (soos menslike slukderm weefsel in hierdie studie) en maak
die ekstraksie van groot hoeveelhede RNS uit klein hoeveelhede van moeilik
hanteerbare weefsel tipes moontlik.
Om saam te vat, hierdie studie het betekenisvolle bydraes gemaak tot die veld
van kankernavorsing deur die ontrafeling van die TP53 mutasiespektrum in beide
laringeale sowel as slukderm kanker, in 'n populasie uniek aan die Wes Kaap.
Die eerste deel van hierdie tesis is gepubliseer in Cancer Geneties and
Cytogenetics (Barnard, D., K. Lehmann, E. G. Hoal, P. D. van Heiden, and T. C.
Victor. 2003. The spectrum of mutations in TP53 in laryngeal cancer patients
from a high-incidence population shows similarites to many of the known
mutational hotspots. Cancer Genetics and Cytogenetics 145: 126-132) en 'n
afskrif van die artikel is ingesluit in Appendix I. Hierdie werk is ook voorgedra
(deur D. Barnard) by 'n internasionale kongres getiteld "Cancer of the
Esophagus and Gastric Cardia: From Gene to Cure", wat in Amsterdam,
Nederland gehou is gedurende 13 - 15 Desember 2002
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Nutrient intake, gastrointestinal microbiota and the effect of Lactobacillus plantarum 299V in irritable bowel syndrome patientsStevenson, Cheryl 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Background: Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder. GI symptoms and impaired quality of life affect between 10-20% of all adults, corresponding to about 25-50% of all patients who visit a gastroenterologist’s clinic. In recent years, several novel mechanisms of IBS that likely relate to previously established theories have been identified. Inflammation, postinfectious low-grade inflammation, immunological and genetic predisposition along with altered microbiota are critical in IBS development, while several dietary factors may also play a role in this syndrome. However, none of these factors accounts for the full repertoire of IBS symptoms, and the pathophysiology of this condition is not fully understood. The overarching aim of this study was to investigate the nutrient intakes, GI microbiota and the effect of Lactobacillus plantarum (L.plantarum) 299v in IBS patients.
Sub-aims: 1) Update healthcare professionals on current probiotic information and provide an overview of probiotic treatment approaches, with special emphasis on IBS, 2) conduct a well designed randomised, double blind, placebo-controlled trial (RCT) with L. plantarum 299v as part of an intervention and establish whether a course of probiotics may alleviate undesirable symptoms of IBS and improve quality of life, 3) assess nutrient intake in patients with irritable bowel syndrome (IBS) compared to dietary recommendations, 4) validate and assess the reproducibility of food records and 5) identify possible nutrient risk components for establishing GI microbiota involved in IBS and as part of an intervention, determine whether a course of probiotics may alter stool microbiota. Results: 1) A review article published by the author provides an overview of current probiotic treatment options to health care professionals and indicates certain probiotics are a promising therapeutic treatment option for management of IBS symtpoms, 2) the effects of the single strain probiotic, L. plantarum 299v, supplementation was evaluated in a RCT. Compared to placebo, the probiotic supplementation showed no significant reduction in GI symptom severity scores, particularly abdominal pain relief. Quality of life was also not improved in the treatment versus control group. Both the treatment and placebo groups improved significantly over the trial period, indicating a large placebo effect, 3) nutrient intakes of the IBS patients compared to current dietary reference recommendations indicates that this group of patients are at risk for nutrient inadequacies in key macro and micronutrients, 4) the validity and reliability of the dietary data showed good reliability but poor validity as measured by plasma fatty acids and 5) the GI microbiota composition in the phenotypically different diarrhoea-predominant IBS (D-IBS) vs. constipation-predominant IBS (C-IBS) showed that D-IBS patients had significantly lower counts of Lactobacillus plantarum compared to C-IBS patients. The probiotic had no significant effects on the GI microbiota as measured by quantitative polymerase chain reaction (qPCR). It was found that nutrient intakes had a significant impact on the microbiota. Lower fibre intakes were associated with higher Bacteroides spp., lower Bifidobacteria bifidum and Lactobacillus plantarum counts in both IBS groups. Conclusion: Taken together, L.plantarum 299v did not alleviate the GI symptoms of IBS, nor was it associated with significant changes in the GI microbiota. IBS patients may be at risk of key nutrient inadequacies. The influence of nutrient intakes on the GI microbiota provides an attractive explanation as a potential pathophysiological factor for IBS. / AFRIKAANSE OPSOMMING: Agtergrond: Prikkelbare derm-sindroom (PDS) is ‘n algemene gastro-intestinale (GI) stoornis. GI simptome affekteer die lewenskwaliteit van 10-20% van alle volwassenes. Dit stem ooreen met ongeveer 25-50% van alle pasiënte wat ‘n gastroënteroloog konsulteer. Verskeie oorspronklike meganismes vir die ontwikkeling van PDS is onlangs identifiseer. Inflammasie, post-infektiewe lae-graadse inflammasie, immunologiese en genetiese vatbaarheid tesame met veranderde mikrobiota is krities vir die ontwikkeling van PDS. Sekere dieetfaktore mag ook bydraend wees tot hierdie sindroom. Geen van hierdie faktore is egter verantwoordelik vir die volle spektrum van PDS simptome nie en die patofisiologie van die toestand word ook nog nie ten volle verstaan nie. Die oorkoepelende doel van hierdie studie is om nutriëntinname, GI mikrobiota en die uitwerking van L.plantarum 299v in PDS pasiënte bepaal. Sub-doelwitte: 1) Om gesondheidswerkers in te lig aangaande die nuutste inligting oor probiotika en om ‘n oorsig van probiotika behandelingsopsies te verskaf, met spesiale klem op PDS, 2) om ‘n goed beplande ewekansige, dubbel-blinde, plasebo-beheerde kliniese studie met L.plantarum 299v as deel van die intervensie uit te voer om sodoende te bepaal of ‘n kursus probiotika ongewensde simptome van PDS kan verbeter en lewenskwaliteit sodoende verhoog, 3) om nutriëntinname in pasiënte met PDS te bepaal vergeleke met dieet aanbevelings, 4) om die geldigheid en herhaalbaarheid van voedselrekords te bepaal en 5) om moontlike nutriënt risikokomponente vir die ontwikkeling van GI mikrobiota betrokke in PDS te identifiseer en om as deel van ‘n intervensie te bepaal of ‘n kursus probiotika stoelgang mikrobiota patrone verander.
Resultate: 1) ‘n Oorsigartikel gepubliseer deur die kandidaat dui probiotika aan as ‘n belowende terapeutiese opsie in die behandeling van PDS simptome, 2) die effek van ‘n enkelstam probiotikum, L.plantarum 299v, is evalueer deur ‘n ewekansige, dubbel-blinde, plasebo-beheerde kliniese studie. Vergeleke met die plasebo, het probiotiese aanvulling geen betekenisvolle vermindering in die GI simptome in PDS pasiënte tot gevolg gehad nie. Lewenskwaliteit het ook nie verbeter in die behandelde versus die kontrole groep nie. Beide die behandelde en plasebo groepe het aansienlik verbeter oor die studietydperk, wat ‘n groot plasebo effek aandui, 3) nutriëntinname van die PDS groep vergeleke met huidige dieetaanbevelings, dui daarop dat hierdie groep pasiënte ‘n risiko het vir die ontwikkeling van kern nutriënttekorte (makro- en mikronutriënte), 4) die geldigheid en betroubaarheid van die dieetdata dui op goeie betroubaarheid, maar swak geldigheid soos bepaal deur plasma vetsure en 5) die dermkanaal mikrobiotiese samestelling in die verskillende fenotipes, diarree-oorheersende PDS (D-PDS) vs. konstipasie-oorheersende PDS (K-PDS) dui daarop dat D-PDS pasiënte aansienlike minder Lactobacillus plantarum gehad het vergeleke met K-PDS pasiënte. Die probiotikum het geen beduidende uitwerking op die oorheersende mikrobiota gehad nie, soos gemeet deur kwantitatiewe polimerase kettingreaksie (kPKR). Daar is gevind dat dieet ‘n beduidende impak op die mikrobiota gehad het. Daar is ‘n verband tussen laer vesel inname en hoёr Bacteroides spp. en laer Bifidobacteria bididum en Lactobacillus plantarum tellings gevind in beide PDS groepe. Gevolgtrekking: Die L.plantarum 299v enkelstam probiotikum het nie die gastrointestinale simptome van PDS pasiënte verlig nie en daar is ook geen beduidende veranderinge in die mikrobiota gevind nie. PDS pasiënte mag ‘n verhoogde risiko toon vir kern nutriënttekorte. Die invloed van nutriëntinname op GI mikrobiota verskaf ‘n belowende verduideliking as ‘n potensiële patofisiologiese faktor in PDS.
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Probiotic properties of lactic acid bacteria evaluated in a gastro-intestinal model and in in vivo pig trialsMare, Louise 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: This study describes the use of a gastro-intestinal model to screen lactic acid bacteria isolated
from the gastro-intestinal tract of post-weaned piglets (raised on six different diets) for
probiotic properties. Intestinal bacteria were isolated from ,the stomach, duodenum, jejunum,
caecum, ileum and colon. The highest cell numbers (6 x 107 cfulg) were isolated from the
ileum. No significant differences in viable cell counts were recorded for piglets raised on the
six diets.
Isolates with the best overall probiotic properties were identified as members of Lactobacillus
salivarius and Lactobacillus fermentum. The two strains selected for further studies were
Lactobacillus plantarum 423 (originally isolated from sorghum beer) and Lactobacillus
salivarius 241 (isolated from pig intestine). Enterococcus faecalis FAIR E 92 was originally
isolated from pig intestine and was included in this study as a non-pathogenic challenge
strain. L. plantarum 423 produces a bacteriocin plantaricin 423, active against E. faecalis
FAIRE 92.
L. plan/arum 423 and L. salivarius 241 were included in the gastro-intestinal model and their
adhesion to the mucus of porcine ileum studied with fluorescent-in-si/u-hybridization (FISH).
A decrease in viable cell numbers of L. plan/arum 423 was recorded in the duodenum,
jejunum and ileum in the presence of bile and pancreatic juice. However, higher cell numbers
were recorded in the caecum and anterior colon, which suggested that strain 423 recovered
from these stress factors. Plantaricin 423 was detected for up to 28 hours in the duodenum,
jejunum, ileum and middle colon. Lower cell numbers (one log unit) of L. salivarius 241
were recorded in the gastro-intestinal model over seven days, compared to strain 423.
Piglets of one, 14 and 28-days-old were dosed with L. plan/arum 423 and L. salivarius 241,
separately and in combination (1: 1). In a separate experiment, 14-day-old piglets were
challenged twice with E. faecalis FAIRE 92, followed by dosage with strains 423 and 241.
New-borne piglets dosed with L. plantarum 423 gained more weight (4 kg over 19 days)
compared to piglets dosed with L. salivarius 241 (2.2 kg over 19 days), or a combination of
the two strains (2 kg over 19 days). Piglets of 14 and 28-days-old, on the other hand, gained
more weight when dosed with a combination of strains 423 and 241. The cell numbers of E.
faecalis FAIR E 92 and other enterococci decreased drastically (two log units) when the piglets were dosed with the latter two strains. Overall, piglets of various ages reacted
differently when administered L. plantarum 423 and L. salivarius 241, separately or in
combination.
Fluorescent-in-situ-hybridization (FISH) was used to study the in vivo adhesion of L.
plantarum and L. salivarius to mucus in the stomach, duodenum, jejunum, ileum, caecum and
colon. The highest number of L. plantarum cells was recorded in the ileum, whereas L.
salivarius favoured adhesion to the duodenum. A decrease in cell numbers of E. faecalis in
the ileum mucus was recorded when a combination of the probiotic strains 423 and 241 was
administered. This study provided a reliable estimation of the presence and/or adhesion of L.
plantarum and L. salivarius to various parts of the porcine gastro-intestinal tract, without the
use of expensive cultivation techniques. Insight was gained into the co-evolution existing
between probiotic bacteria and the porcine gastro-intestinal tract, emphasizing the use of
gastro-intestinal models to study the dynamics of the gastro-intestinal tract. / AFRIKAANSE OPSOMMING: Hierdie studie beskryf die gebruik van 'n gastro-intestinale model, om melksuurbakterieë wat
geïsoleer is uit die spysverteringskanaal (SVK) van reeds gespeende varkies (gevoed op ses
verskillende diëte) vir probiotiese eienskappe te toets. Ingewandsbakterieë is uit die maag,
duodenum, jejunum, caecum, ileum en kolon geïsoleer. Die hoogste aantal selle (6 x 107
kve/g) is geïsoleer uit die ileum. Geen betekenisvolle verskille in lewensvatbare seltellings,
vir varkies gevoed op ses verskillende voere is aangeteken nie.
Isolate met die beste algehele probiotiese eienskappe is as Lactobacillus salivarius en
Lactobacillus fermentum geïdentifiseer. Vir verdere studie is twee isolate Lactobacillus
plantarum (oorspronklik uit sorghum-bier geïsoleer) en Lactobacillus salivarius (uit die
varkdermkanaal geïsoleer) geselekteer. Enterococcus faecalis FAIRE 92, oorspronklik uit
die varkdermkanaal geïsoleer, is in hierdie studie as 'n nie-patogeniese indikator gebruik. L.
plantarum 423 produseer 'n bakteriosien plantarisien 423 wat aktief is teen E. faecalis FAIR
E92.
L. plantarum 423 en L. sa/ivarius 241 is ingesluit in die gastro-intestinale model, en
vashegting van die bakterieë aan die mukus van vark-ileum is met fluoresensie-in-si/uhibridisasie
(FISH) bestudeer. 'n Afname in lewende selgetalle van L. plan/arum 423 in die
duodenum, jejunum en ileum is aangetoon in reaksie tot die byvoeging van gal en
pankreatiese sappe. Hoër selgetalle is nietemin aangeteken in die caecum en voorste gedeelte
van die kolon, wat 'n aanduiding gee dat isolaat 423, ten spyte van hierdie stres-faktore,
oorleef. Plantaricin 423 is vir 'n tydperk (28 uur) in die duodenum, jejunum, ileum en
sentrale kolon gevind. Laer selgetalle (een logaritmiese eenheid) van L. salivarius 241 is in
die gastro-intestinale modeloor 'n tydperk van sewe dae aangetoon, in vergelyking met
isolaat 423.
Een, 14 en 28 dag oud varkies is met L. plantarum 423 en L. salivarius 241 (afsonderlik en in
kombinasie 1:1) twee keer gedaag met E. faecalis FAIR E 92, opgevolg met dosering van
423 en 241. Pasgebore varkies het die hoogste gewigstoename getoon (4 kg oor 19 dae) na
dosering met L. plantarum 423 in vergelyking met varkies gedoseer met L. salivarius 241
(2.2 kg oor 19 dae) of 'n kombinasie van die twee isolate (2 kg oor 19 dae). Daarenteen het
veertien- en 28 dag oud varkies beter gewigstoename getoon na dosering met 'n kombinasie van isolate 423 en 241. Die selgetalle van E. faecalis FAIRE 92 en ander enterococci het
drasties afgeneem (twee logaritmiese eenhede) nadat die varkies met laasgenoemde twee
isolate gedoseer is. Varkies van onderskeie ouderdom het verskillend gereageer na dosering
met L. plantarum 423 en L. salivarius 241 afsonderlik of in kombinasie.
Fluoresensie-in-situ-hibridisasie (FISH) is gebruik om die in vivo vashegting van L
plantarum en L. salivarius tot die vark mukus in die maag, duodenum, jejunum, ileum,
caecum en kolon te bestudeer. Die hoogste telling van L. plantarum selle is aangeteken in die
ileum, terwyl L. salivarius aanhegting tot die duodenum verkies het. 'n Afname in seltellings
van E. faecalis in die ileum mukus was aangeteken na toediening met 'n kombinasie van
probiotiese isolate 423 en 241. Hierdie studie het 'n betroubare bepaling van die voorkoms
en/ofvashegting van L. plantarum en L. sa/ivarius isolate in verskeie gedeeltes van die varkspysverteringskanaal
voorsien, sonder die hulp van duur kwekings tegnieke. Probiotiese
bakterieë is in 'n gastro-intestinale model, wat die natuurlike omgewing verteenwoordig,
bestudeer. Insig oor die ko-evolusie tussen probiotiese bakterieë en die SVK van die vark is
verkry. Die gebruik van 'n gastro-intestinale model om die dinamika van die SVK te
bestudeer is met hierdie studie beklemtoon.
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Novel IGH translocations in gastric non-Hodgkin's B-cell lymphomaHu, Xiaotong., 胡曉彤. January 2007 (has links)
published_or_final_version / abstract / Pathology / Doctoral / Doctor of Philosophy
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Expression analysis of Hoxb5 in enteric neurons and generation of Tamoxifen inducible Cre mice for neuronal Hoxb5 signalingperturbationKam, Ka-man., 甘嘉敏. January 2008 (has links)
published_or_final_version / Surgery / Master / Master of Philosophy
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