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Classes of Compounds with GI Tract Toxicity
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
Amy L. Mihalchik, Erica N. Rogers
Alcohol has been shown to induce gut dysbiosis (microbial imbalance) in vivo and in humans; additionally, intestinal dysbiosis and translocation of pathogenic bacteria in the GI tract have been associated with pathogenesis of alcoholic liver disease (Cresci, 2015). The microbiome, composed of trillions of microorganisms sensitive to environmental and dietary changes, forms a symbiotic relationship with the GI tract, aiding in extraction of nutrients from food and barrier protection to pathogenic organisms (Engen et al., 2015). Hartmann et al. (2015) suggested that alcoholics, alcoholics with liver cirrhosis, and moderate drinkers all had observed changes in the quantity and ratio of microbial species present in the gut, with lower levels of beneficial commensal bacteria such as Lachnospiraceae, Ruminococcacaeae, and Clostridiales Family XIV Incertae sedis and increased levels of potentially pathogenic bacteria such as Enterobacteriaceae, Streptococcaceae, and Veillonellaceae, especially in cirrhotic patients. Upon cessation of alcohol use, eubiosis (microbial balance) can be at least partially restored (Hartmann et al., 2015).
Cough Formation in Viral Infections in Children
Published in Sunit K. Singh, Human Respiratory Viral Infections, 2014
O’Grady Kerry-Ann F., Ian M. Mackay, Anne B. Chang
Next-generation or high-throughput sequencing has been used to examine the diversity of bacteria in the URT.179,180 This diversity is usually quantified in terms of the 16S rDNA sequence. The healthy adult nasopharynx is notable for the presence of skin lineages, including Staphylococcaceae, Propionibacteriaceae, and Corynebacteriaceae, and those found in the oral cavity such as Streptococcaceae, Veillonellaceae, and Prevotellaceae, but that each adult’s URT and LRT microbial communities are more similar to within individuals than between individuals.180
Clinical Features of Colorectal Adenoma and Adenocarcinoma
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Jamie Murphy, Norman S. Williams
The bile-salt/bacteria theory gains credence when it is considered that the bile acids have a chemical structure similar to that of carcinogens such as methylcholanthrene. Furthermore, it is known that certain bacteria, particularly Clostridium paraputrificum, can dehydrogenate the steroid nucleus, an effect that might be important in the development of compounds with structures similar to that of known carcinogens. It is therefore of particular interest that some authors have found that C. paraputrificum is particularly prevalent in the intestinal flora of high-risk groups. Likewise, others have noted its presence in the faeces of colon cancer patients more often than in those of control subjects. Hill et al.55 also noted that the excretion of bile acids is greater and the ratio of anaerobic to aerobic bacteria in faeces is higher in subjects from countries with a high colorectal cancer incidence than in those with a low incidence. Certain anaerobes are more active in the degradation of bile acids, and it is found that excreted bile acids are more often degraded in high-incidence populations than in low-incidence ones. It thus appears that bacteria within the large bowel do have an important role in colon carcinogenesis. However, although certain organisms have been identified to be in higher concentrations within tumours as compared to normal colon (including Bacteroidaceae, Streptococcaceae, Fusobacteriaceae, Peptostreptococcaceae, Veillonellaceae and Pasteurellaceae species), there are no hard data linking a specific bacterium to the development of colorectal carcinoma.56 Many of the studies involve only small numbers of patients, and any given patient may have more than 400 identifiable species of bacteria in the gut. Thus, a number of practical factors make interpretation of these results difficult despite recent technical and conceptual advances in characterising the taxonomic composition, metabolic capacity and immunomodulatory activity of the human gut microbiota.
Interaction effect between NAFLD severity and high carbohydrate diet on gut microbiome alteration and hepatic de novo lipogenesis
Published in Gut Microbes, 2022
Hyena Kang, Hyun Ju You, Giljae Lee, Seung Hyun Lee, Taekyeong Yoo, Murim Choi, Sae Kyung Joo, Jeong Hwan Park, Mee Soo Chang, Dong Hyeon Lee, Won Kim, GwangPyo Ko
Alterations in the gut microbiome according to NAFLD severity in the HC group were confirmed by comparing the gut microbiome composition of the NAFLD cohort with that of the non-NAFLD cohort. The gut microbiome composition of the non-NAFLD cohort, unlike that of the NAFLD cohort, stratified by the HSI in the HC group was not significantly altered by the HSI. This indicates that the contributing factor to the alteration of the gut microbiome composition is the interaction between NAFLD severity and an HC diet rather than their individual effects. On the other hand, univariate and multivariate analyses of the gut microbiome in the NAFLD cohort showed that the abundance of Veillonellaceae was not significantly enriched with worsening NAFLD severity in the HC group. However, the abundance of Veillonellaceae significantly increased with high HSI (>30) in the HC group of the non-NAFLD twin cohort. Thus, we speculate that the enrichment of the abundance of Veillonellaceae in the HC group is related with hepatic steatosis but not with severe NASH. Although several previous studies reported the association between Veillonellaceae and NAFLD,11,34 further studies on the colonization of Veillonellaceae during the certain stages of NAFLD under HC consumption are warranted.
Gut microbiota in mucosa and feces of newly diagnosed, treatment-naïve adult inflammatory bowel disease and irritable bowel syndrome patients
Published in Gut Microbes, 2022
Hana Čipčić Paljetak, Anja Barešić, Marina Panek, Mihaela Perić, Mario Matijašić, Ivana Lojkić, Ana Barišić, Darija Vranešić Bender, Dina Ljubas Kelečić, Marko Brinar, Mirjana Kalauz, Marija Miličević, Dora Grgić, Nikša Turk, Irena Karas, Silvija Čuković-Čavka, Željko Krznarić, Donatella Verbanac
Compared to microbiota footprint of healthy individuals (Table 3), both IBD and IBS had a marked increase in the abundance of Proteobacteria, most notably Enterobacteriaceae, as well as Eubacterium. Relative enrichment of Dialister was noted in CD and UC patients. At the same time, IBD specimens (CD in particular) display decreased abundance of several families belonging to the order Clostridiales, most notable being the depletion of Christensenellaceae. IBD affected individuals had several protective taxa depleted, particularly a significant depletion of Anaerostipes and Ruminococcus, a marked reduction of A. muciniphila, and a moderate decrease of F. prausnitzii. Adlercreutzia and Lactobacillus were also depleted in IBD. In CD patients, depletion of Veillonellaceae is noted, with significant reduction in the abundance of Phascolarctobacterium genus. R. gnavus was more abundant in all patients compared to healthy group, reaching statistical significance in CD. Although there is an increase in taxa belonging to the Bacteroidetes phylum across patient groups, the most prominent difference distinguishes IBS from healthy controls.
Fecal microbiota transplantation in hepatic encephalopathy: a systematic review
Published in Scandinavian Journal of Gastroenterology, 2021
Mathias Madsen, Nina Kimer, Flemming Bendtsen, Andreas Munk Petersen
FMT was found to have a positive effect on liver function parameters, indicating that it could be a useful therapeutic component in decompensated cirrhosis in general. Furthermore, it was associated with a reduction in inflammatory mediators, which are known to be an important driver of cirrhosis-associated complications [10–12]. The exact mechanism responsible for the reduction in inflammatory mediators was not investigated in depth, but as gut bacterial translocation is anticipated to be a main causal factor in the development of inflammation among patients with cirrhosis [7,8], FMT may attenuate translocation by restoring the intestinal lining [9,20]. Improved liver function parameters may also be ascribed to this same mechanism, as well as the immunomodulatory effects of increased SCFA synthesis [23,24]. Notably, comparison of changes in taxon relative abundance among studies that assessed liver function parameters, showed a sixfold increased relative abundance of the Veillonellaceae species Megasphaera elsdenii post-FMT in patients with drastically improved MELD score and ascites resolution [33]. The Veillonellaceae family decreased in relative abundance among patients that showed no improvement in liver function parameters [21,29]. The Megasphaera genus has previously been shown to correlate with HE [25]; however, low levels of Clostridium cluster IX, which comprises Megasphaera, have been shown to correlate with portal hypertension [41], although findings need to be supported by further studies.