Toxoplasma gondii
Peter D. Walzer, Robert M. Genta in Parasitic Infections in the Compromised Host, 2020
It has long been suggested that the activated macrophage plays a preeminent role in the resistance to toxoplasma infection. Peritoneal macrophages from mice acutely and chronically infected with Toxoplasma have a remarkable ability to kill not only intracellular Toxoplasma (203) but also other unrelated phylogenetically distinct facultative and obligate intracellular pathogens (204) as well as tumor target cells (205). Macrophages and human monocyte-derived macrophages become activated after being exposed to lymphokines produced by sensitized lymphocytes cocultured with Toxoplasma antigen (206-209). The ability of lympohcytes from acutely infected mice to activate macrophages in vitro correlated temporarily with the in vivo acquisition of activated macrophages (194). The major mediator of macrophage activation is gamma-interferon (210,211). As discussed earlier, the induction of increased microbial activity is associated with increased oxygen-dependent and independent mechanisms of microbial activity.
Gastrointestinal Tract Development and Its Importance in Toxicology
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
Mercury and arsenic are also metabolized in the gut. Methylmercury, for example, is demethylated by fecal bacteria to elemental mercury in rodent models, and in vitro models have shown that inorganic arsenic can be methylated to more toxic forms, such as monomethylarsonic and monomethylarsonous acids (National Academies of Science, Engineering, and Medicine, 2017). The translation of the in vitro findings to in vivo systems is yet to be verified (National Academies of Science, Engineering, and Medicine, 2017). Our understanding of microbial metabolism of pharmaceuticals is more advanced than that for environmental toxicants where the relative importance of their bioactivation and detoxification by the gut microbiome requires much further investigation.
Biological behavior of titanium, zirconia or PEEK dental implant-abutments
J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares in Biodental Engineering V, 2019
The oral cavity represents a challenging environment for all biomaterials since they are exposed to biofilm formation, which negatively affects their long-time performance. The biofilm is a complex microbial community with a large number of species, including bacteria and fungi, that gathers substances from food, saliva and microbial metabolism (Köunönen et al. 1992). The process starts when the implant-abutment is rapidly covered with a salivary protein pellicle. The adsorbed proteins offer a range of binding sites for oral bacteria to attach and initiate the development of a microbial biofilm (Dorkhan et al. 2014a, Rutkunas et al. 2015). Several bacterial species have been related to be involved in the pathogenesis of periodontal and peri-implantar diseases. Microbial adhesions on surfaces are typically tested by in vitro models with one or more bacterial strains. However, the oral microbial ecology contains hundreds of species, which is extremely difficult to simulate through in vitro studies (Xing et al. 2015).
Effects of chronic cadmium exposure on the structure and function of intestinal mucosal flora in mice
Published in Toxin Reviews, 2022
Xiaoya Li, Yi Wu, Guozhen Xie, Zhoujin Tan
Microbial activity often represents the overall activity of microbial hydrolase, which can be used as an important indicator of the ability of microorganisms to decompose substances (Tang 2020). FDA is hydrolyzed by nonspecific enzymes (esterases, proteases, lipases, etc.) in bacteria and fungi, whose hydrolytic activity is proportional to the number of microbial populations (Swisher and Carroll 1980). The mammalian intestine hosts the wide variety of microorganisms and the overall metabolic capacity of the microorganisms in the animal intestine can be reflected by measuring the FDA hydrolytic activity of the intestinal samples. Referring to the literature, the small intestinal mucosa of mice in each group was collected under aseptic environment (Schnürer and Rosswall 1982). The samples of the same group were collected together in sterile tubes and stored at −80 °C. 2.5 ml of FDA storage solution added to the prepared phosphate buffer solution to make A solution. 2 ml of A solution was added to 50 μL of the solution to be measured in a sterile test tube and shaken at 24 °C for 90 min, then 2 ml of acetone was added and the absorbance value was measured at 490 nm. Each sample was measured 3 times in parallel. The absorbance was measured at 490 nm. 2 ml of A solution was added to 2 ml of acetone and 50 μL of the solution to be measured, and the reaction was carried out for 90 min at 24 °C in a shaker as a blank control. The microbial activity per unit mass of sample was expressed as the fluorescein absorbance value.
Subsea tunnel reinforced sprayed concrete subjected to deterioration harbours distinct microbial communities
Published in Biofouling, 2018
Sabina Karačić, Britt-Marie Wilén, Carolina Suarez, Per Hagelia, Frank Persson
However, basic knowledge about the specific role of the community structure of the microbial biofilms in the subsea tunnels, as well as of biofilms on related concrete structures in marine environments, is lacking. In order to understand and ultimately prevent deterioration processes caused by microbial activity, such knowledge is pivotal. In this study high throughput amplicon sequencing of 16S rRNA genes was used to assess the composition, diversity and community assembly of microbial biofilms at three sites subjected to concrete deterioration in the Oslofjord subsea tunnel. The chemical microenvironment within the biofilm was measured in situ, using oxygen and pH microelectrodes, as well as measurement of the chemical composition of water and biofilm with the aim of providing a linkage between the biofilm community structure and the environmental conditions.
Effects of Fatty Acids on Hematological Neoplasms: A Mini Review
Published in Nutrition and Cancer, 2022
Silvia Giannattasio, Maria Dri, Giuseppe Merra, Giovanna Caparello, Tiziana Rampello, Laura Di Renzo
Nutrition plays a fundamental role in the composition of the microbiota, consequently the composition of the microbiota has a profound influence on human health (29). Several studies have highlighted the pronounced effect of diet on the microbiota which plays the role of mediator of the diet-induced modulation of host cell processes, probably through the generation of selective microbial metabolites. Many studies highlight the effect of microbial metabolites, including short-chain fatty acids (SCFA) in cancer and immune homeostasis (30, 31, ). In particular, in a study conducted on humans, they saw the effect of a high-fat Western diet in African Americans and the effect of a more restricted, high-fiber diet in a genetically similar rural African population. African Americans had a higher risk of developing cancer than white Americans (32). Additionally, when African Americans switched to a high-fiber, low-fat diet, an increase in SCFA butyrate-producing microbes, known for its protective and anticancer effects in mice, was observed. While rural Africans have switched to a diet low in fiber and high in fat, causing the increase in gene expression of the bacteria responsible for the production of bile acids. It is therefore interesting to note how the change in diet led to the modulation of microbial activity and the alteration of the production of microbial metabolites (33).
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