Biomedical subjects

Nina Rautonen

Publications and source records attributed to Nina Rautonen.

7 recordsLinked to original sources

PubMed2005

Prebiotics and other microbial substrates for gut functionality.

The intestinal microbiota is of great importance to our health and wellbeing. Modulation of the intestinal microbiota by exogenous and endogenous substrates can be expected to improve various physiological functions of our body, not just those in the intestine. Recently, new targets such as immune function and areas outside the colon have been considered to be influenced by the intestinal microbiota. Novel approaches might include the application of prebiotics in different combinations or the provision of nutrients to different bacterial groups and to different parts of the intestine.

Bifidobacterium↗

PubMed2005

In vitro effects on polydextrose by colonic bacteria and caco-2 cell cyclooxygenase gene expression.

A 4-stage colon simulator and a cell culture-based human intestinal epithelial function model were combined to study the effects of a soluble fiber, polydextrose (PDX), on intestinal microbes and mucosal functions relevant to the risk of colon cancer. We observed sustained degradation of PDX throughout the different stages of the model. The fermentation was characterized by gradual degradation of PDX, production of short-chain fatty acids, and no increasing in putrefactive markers. We observed less marked effects in the microbial densities. When we applied colon fermentation metabolites obtained from the simulators with PDX to Caco-2 colon cancer cell line, a significant dose-dependent decreasing effect on cyclooxygenase-2 (COX-2) and an increasing effect on COX-3 expression levels were observed. PDX concentration appeared not to have effect on the expression levels of COX-1. Overexpression of COX-2 and decreased expression of COX-1 have been suggested to be characteristics of colon cancer. The exact physiological role of COX-3, an intron-retaining splice variant of COX-1, is not known, but it is suspected to play a role in transcriptional regulation of COX-1 and COX-2. In vitro modulation of COX expression by colon microbial fermentation products of polydextrose offers an interesting starting point for further studies on possible risk-decreasing effect of PDX on the development of colon cancer.

Bacteria↗

PubMed2004

Combination of polydextrose and lactitol affects microbial ecosystem and immune responses in rat gastrointestinal tract.

The effects of various dietary fibres on gut health have been studied extensively but their combined effects are scarcely documented. In the present study the effects of 2 % (w/w) polydextrose (PDX), 2 % (w/w) disaccharide lactitol, or 2 % (w/w) PDX+2 % (w/w) lactitol on gut microflora, microbial metabolism and gut immune responses were investigated in rats. Both PDX and lactitol alone had an effect on many of the studied parameters, but their combination had stronger than additive effects in some parameters. The PDX+lactitol combination altered the microbial community structure as seen by a culture-independent method, percentage guanine+cytosine (%G+C) profiling, increasing the areas of %G+C 35-39 (P<0.0001) and %G+C 45-49 (P=0.0002), and decreasing %G+C 65-74 (P<0.0003). These changes were also reflected in the microbial metabolism so that the production of biogenic amines and branched volatile fatty acids was significantly reduced, by 12 (P=0.03) and 50 % (P=0.002), respectively, indicating a shift from putrefactive towards saccharolytic metabolism. PDX increased the secretion of IgA in the caecum (P=0.007). Secretion of IgA increased even more, almost ten-fold, with the combination of PDX+lactitol (P<0.0001) when compared with the control group. Lactitol increased the production of butyrate by caecal microbes by two- to three-fold when compared with the PDX or control group (P<0.0001). Butyrate is a preferred energy source for mucosal cells; thus a boost in the availability of energy for immune cells may have still added to the synergistic effects of PDX and lactitol on immune cells. It is noteworthy that improvement in the IgA secretion occurred without signs of mucosal inflammation.

Animals↗

PubMed2004

Polydextrose, lactitol, and fructo-oligosaccharide fermentation by colonic bacteria in a three-stage continuous culture system.

In vitro fermentations were carried out by using a model of the human colon to simulate microbial activities of lower gut bacteria. Bacterial populations (and their metabolic products) were evaluated under the effects of various fermentable substrates. Carbohydrates tested were polydextrose, lactitol, and fructo-oligosaccharide (FOS). Bacterial groups of interest were evaluated by fluorescence in situ hybridization as well as by species-specific PCR to determine bifidobacterial species and percent-G+C profiling of the bacterial communities present. Short-chain fatty acids (SCFA) produced during the fermentations were also evaluated. Polydextrose had a stimulatory effect upon colonic bifidobacteria at concentrations of 1 and 2% (using a single and pooled human fecal inoculum, respectively). The bifidogenic effect was sustained throughout all three vessels of the in vitro system (P = 0.01 seen in vessel 3), as corroborated by the bacterial community profile revealed by %G+C analysis. This substrate supported a wide variety of bifidobacteria and was the only substrate where Bifidobacterium infantis was detected. The fermentation of lactitol had a deleterious effect on both bifidobacterial and bacteroides populations (P = 0.01) and decreased total cell numbers. SCFA production was stimulated, however, particularly butyrate (beneficial for host colonocytes). FOS also had a stimulatory effect upon bifidobacterial and lactobacilli populations that used a single inoculum (P = 0.01 for all vessels) as well as a bifidogenic effect in vessels 2 and 3 (P = 0.01) when a pooled inoculum was used. A decrease in bifidobacteria throughout the model was reflected in the percent-G+C profiles.

Bacteria↗

PubMed2003

Imbalanced cytokine secretion in newborns.

In adults, a balance between Th1 and Th2 cytokine networks has been proposed to be associated with a healthy status. Newborn babies are reported to express Th2-type immune reactions. Further, the impaired protection of newborn babies against infections has been attributed to a deficient secretion of interferon gamma (IFN-gamma) and interleukin-10 (IL-10). Using IFN-gamma and IL-10 as surrogate markers of Th1 and Th2 orientation, we compared the patterns of IFN-gamma and IL-10 secretion by peripheral blood mononuclear cells between 52 healthy newborns and 35 adults. The baseline secretion of IFN-gamma in adults was similar to that of newborns. The lipopolysaccharide-stimulated IFN-gamma secretion was higher in newborns than in adults, whereas the concanavalin-A-stimulated IFN-gamma secretion was higher in adults. The unstimulated and stimulated IL-10 secretion was significantly lower in newborns than in adults. Using a threshold level of 1,000 pg/ml, we classified neonates and adults on the basis of their stimulated IL-10 and IFN-gamma secretion. Four different groups were identified: IL-10-oriented secretion, IFN-gamma- oriented secretion, balanced high secretion, and balanced low secretion. Only 25% of the neonates had a high IL-10 and a high IFN-gamma secretion as compared with 77% of the adults. Eight percent of the newborns, but none of the adults, had a low secretion of both cytokines. Thirty-six percent of the neonates, but only 5% of the adults, had a high IL-10 and a low IFN-gamma secretion. Thirty-one percent of the neonates and 18% of the adults had a high IFN-gamma secretion, but a low IL-10 secretion. We conclude that neonates have an immature IL-10 and IFN-gamma response as compared with adults. However, individual neonates may have a mature cytokine secretion, whereas others may have a Th1- or a Th2-directed immune response.

Adult↗

PubMed2002

Culture-independent microbial community analysis reveals that inulin in the diet primarily affects previously unknown bacteria in the mouse cecum.

Inulin is a well-known fructose-based prebiotic which has been shown to stimulate the growth of bifidobacteria, a bacterial group generally considered beneficial for intestinal health. In the present study, we analyzed inulin-associated shifts in the total bacterial community of wild-type mice and mice carrying a genetically inactivated adenomatous polyposis coli tumor suppressor gene by using DNA-based approaches independent of bacterial culturability. Mice were fed a high-fat, nonfiber diet with or without inulin inclusion at a 10% (wt/wt) concentration. Cecal contents were analyzed after 0, 3, and 9 weeks on the experimental diets. Inulin inclusion significantly affected the total bacterial community structure of the cecum as determined by both a nonselective percent-guanine-plus-cytosine-based profiling analysis and a more specific 16S ribosomal DNA sequence analysis. The shifts included stimulation of bifidobacteria and suppression of clostridia, but sequence comparison revealed that the major shifts were within previously unknown bacterial taxa. Concomitantly, significantly higher bacterial densities, determined by flow cytometry, were observed with the inulin-amended diet, and the metabolism of the cecal bacterial community was altered, as indicated by higher levels of residual short-chain fatty acids, particularly lactic acid. With regard to all of the microbiological parameters measured, the wild-type mice and mice carrying a genetically inactivated adenomatous polyposis coli tumor suppressor gene were essentially identical. Studies of the implications of pre- and probiotics may need to be expanded to include careful analysis of their effects on the entire microbial community, rather than just a few well-known species. Further studies are needed to increase our understanding of the possible roles of currently unknown gastrointestinal bacteria in health and disease.

Animal Feed↗

PubMed2002

In vitro adhesion specificity of indigenous Lactobacilli within the avian intestinal tract.

In vitro adherence of Lactobacillus strains to cell and tissue types along the chicken alimentary tract and to ileal mucus were determined. Fresh isolates from chickens adhered to the epithelium of crop and, in a strain-dependent manner, to follicle-associated epithelium and the apical surfaces of mature enterocytes of intestinal villi. No adherence to the apical surfaces of undifferentiated enterocytes, the mucus-producing goblet cells, or the ileal mucus was detected.

Adhesins, Bacterial↗