Summary
Background Gut microflora‐mucosal interactions may be involved in the pathogenesis of irritable bowel syndrome (IBS).
Aim To investigate the efficacy of a novel prebiotic ...trans‐galactooligosaccharide in changing the colonic microflora and improve the symptoms in IBS sufferers.
Methods In all, 44 patients with Rome II positive IBS completed a 12‐week single centre parallel crossover controlled clinical trial. Patients were randomized to receive either 3.5 g/d prebiotic, 7 g/d prebiotic or 7 g/d placebo. IBS symptoms were monitored weekly and scored according to a 7‐point Likert scale. Changes in faecal microflora, stool frequency and form (Bristol stool scale) subjective global assessment (SGA), anxiety and depression and QOL scores were also monitored.
Results The prebiotic significantly enhanced faecal bifidobacteria (3.5 g/d P < 0.005; 7 g/d P < 0.001). Placebo was without effect on the clinical parameters monitored, while the prebiotic at 3.5 g/d significantly changed stool consistency (P < 0.05), improved flatulence (P < 0.05) bloating (P < 0.05), composite score of symptoms (P < 0.05) and SGA (P < 0.05). The prebiotic at 7 g/d significantly improved SGA (P < 0.05) and anxiety scores (P < 0.05).
Conclusion The galactooligosaccharide acted as a prebiotic in specifically stimulating gut bifidobacteria in IBS patients and is effective in alleviating symptoms. These findings suggest that the prebiotic has potential as a therapeutic agent in IBS.
Summary
Background
Prebiotics have been shown to reduce abdominal symptoms in patients with functional gut disorders, despite that they are fermented by colonic bacteria and may induce gas‐related ...symptoms.
Aim
To investigate changes in the metabolic activity of gut microbiota induced by a recognised prebiotic.
Methods
Healthy subjects (n = 20) were given a prebiotic (2.8 g/day HOST‐G904, HOST Therabiomics, Jersey, Channel Islands) for 3 weeks. During 3‐day periods immediately before, at the beginning and at the end of the administration subjects were put on a standard diet (low fibre diet supplemented with one portion of high fibre foods) and the following outcomes were measured: (i) number of daytime gas evacuations for 2 days by means of an event marker; (ii) volume of gas evacuated via a rectal tube during 4 h after a test meal; and (iii) microbiota composition by faecal Illumina MiSeq sequencing.
Results
At the beginning of administration, HOST‐G904 significantly increased the number of daily anal gas evacuations (18 ± 2 vs. 12 ± 1 pre‐administration; P < 0.001) and the volume of gas evacuated after the test meal (236 ± 23 mL vs. 160 ± 17 mL pre‐administration; P = 0.006). However, after 3 weeks of administration, these effects diminished (11 ± 2 daily evacuations, 169 ± 23 mL gas evacuation). At day 21, relative abundance of butyrate producers (Lachnospiraceae) correlated inversely with the volume of gas evacuated (r = −0.52; P = 0.02).
Conclusion
The availability of substrates induces an adaptation of the colonic microbiota activity in bacterial metabolism, which produces less gas and associated issues. Clinical trials.gov NCT02618239.
Linked ContentThis article is linked to Staudacher paper. To view this article visit https://doi.org/10.1111/apt.13976.
Background
We have shown that a galactooligosaccharide prebiotic administration (HOST‐G904) initially increased intestinal gas production and this increase declined back to baseline after 2 week ...administration. Our aim was to determine the mechanism of microbiota adaptation; i.e., to determine whether the net reduction is due to decreased overall production or increased gas consumption.
Methods
In 10 healthy subjects, intestinal gas production and intraluminal disposal was measured before, at the beginning and after 2 week of HOST‐G904 prebiotic administration. Anal gas was collected for 4 hour after a probe meal. Paired studies were performed without and with high‐rate infusion of exogenous gas (24 mL/min) into the jejunum to wash‐out the endogenous gas produced by bacterial fermentation. The exogenous gas infused was labeled (5% SF6) to calculate the proportion of endogenous gas evacuated.
Key Results
The volume of intestinal gas produced i.e., endogenous gas washed‐out, increased by 37% at the beginning of HOST‐G904 administration (P=.049 vs preadministration) and decreased down to preadministration level after 2 week administration (P=.030 vs early administration). The proportion of gas eliminated from the lumen before reaching the anus tended to increase after 2‐week administration (87±3% vs 78±5% preadministration; P=.098).
Conclusions & Inferences
Adaptation to regular consumption of HOST‐G904 prebiotic involves a shift in microbiota metabolism toward low‐gas producing pathways, with a non‐significant increase in gas‐consuming activity. Hence, regular consumption of HOST‐G904 regulates intestinal gas metabolism: less gas is produced and a somewhat larger proportion of it is consumed.
Effect of HOST‐G904 administration on the volume of gas evacuated. Anal evacuation of endogenous gas (produced by bacterial fermentation) 2‐4 hours after a probe meal with and without gaseous wash‐out measured before, at the beginning and after 2 week administration (n=10). With gaseous wash‐out, most endogenous gas produced by colonic fermentation was flushed out and evacuated per anus: gas production increased in the early administration phase and returned back to baseline. Without wash‐out, a large proportion of the gas produced by bacterial fermentation was eliminated from the lumen before reaching the anus and the proportion tended to increase during HOST‐G904 administration.
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Background/Objectives: Prebiotics have attracted interest for their ability to positively affect the colonic microbiota composition, thus increasing resistance to infection and diarrhoeal disease. ...This study assessed the effectiveness of a prebiotic galacto-oligosaccharide mixture (B-GOS) on the severity and/or incidence of travellers' diarrhoea (TD) in healthy subjects. Subjects/Methods: The study was a placebo-controlled, randomized, double blind of parallel design in 159 healthy volunteers, who travelled for minimum of 2 weeks to a country of low or high risk for TD. The investigational product was the B-GOS and the placebo was maltodextrin. Volunteers were randomized into groups with an equal probability of receiving either the prebiotic or placebo. The protocol comprised of a 1 week pre-holiday period recording bowel habit, while receiving intervention and the holiday period. Bowel habit included the number of bowel movements and average consistency of the stools as well as occurrence of abdominal discomfort, flatulence, bloating or vomiting. A clinical report was completed in the case of diarrhoeal incidence. A post-study questionnaire was also completed by all subjects on their return. Results: Results showed significant differences between the B-GOS and the placebo group in the incidence (P<0.05) and duration (P<0.05) of TD. Similar findings occurred on abdominal pain (P<0.05) and the overall quality of life assessment (P<0.05).
BACKGROUND: Aging is associated with reduced numbers of beneficial colonic bifidobacteria and impaired immunity. Galactooligosaccharides (GOSs) stimulate the growth of bifidobacteria in younger ...adults, but little is known about their effects in the elderly and their immunomodulatory capacity. OBJECTIVE: We assessed the effect of a prebiotic GOS mixture (B-GOS) on immune function and fecal microflora composition in healthy elderly subjects. DESIGN: In a double-blind, placebo-controlled, crossover study, 44 elderly subjects were randomly assigned to receive either a placebo or the B-GOS treatment (5.5 g/d). Subjects consumed the treatments for 10 wk, and then went through a 4-wk washout period, before switching to the other treatment for the final 10 wk. Blood and fecal samples were collected at the beginning, middle (5 wk), and end of the test period. Predominant bacterial groups were quantified, and phagocytosis, natural killer (NK) cell activity, cytokine production, plasma cholesterol, and HDL cholesterol were measured. RESULTS: B-GOS significantly increased the numbers of beneficial bacteria, especially bifidobacteria, at the expense of less beneficial groups compared with the baseline and placebo. Significant increases in phagocytosis, NK cell activity, and the production of antiinflammatory cytokine interleukin-10 (IL-10) and significant reduction in the production of proinflammatory cytokines (IL-6, IL-1β, and tumor necrosis factor-α) were also observed. B-GOS exerted no effects on total cholesterol or HDL-cholesterol production, however. CONCLUSIONS: B-GOS administration to healthy elderly persons resulted in positive effects on both the microflora composition and the immune response. Therefore, B-GOS may be a useful dietary candidate for the enhancement of gastrointestinal health and immune function in elderly persons.
The global kernel k-means clustering algorithm Tzortzis, G.; Likas, A.
2008 IEEE International Joint Conference on Neural Networks (IEEE World Congress on Computational Intelligence),
06/2008, Letnik:
10
Conference Proceeding, Journal Article
Kernel k-means is an extension of the standard k-means clustering algorithm that identifies nonlinearly separable clusters. In order to overcome the cluster initialization problem associated with ...this method, in this work we propose the global kernel k-means algorithm, a deterministic and incremental approach to kernel-based clustering. Our method adds one cluster at each stage through a global search procedure consisting of several executions of kernel k-means from suitable initializations. This algorithm does not depend on cluster initialization, identifies nonlinearly separable clusters and, due to its incremental nature and search procedure, locates near optimal solutions avoiding poor local minima. Furthermore a modification is proposed to reduce the computational cost that does not significantly affect the solution quality. We test the proposed methods on artificial data and also for the first time we employ kernel k-means for MRI segmentation along with a novel kernel. The proposed methods compare favorably to kernel k-means with random restarts.
BACKGROUND: Galactooligosaccharides are selectively fermented by the beneficial member of the colonic microflora contributing to the health of the host. OBJECTIVE: We assessed the prebiotic potential ...of a novel galactooligosaccharide produced through the action of β-galactosidases, originating from a probiotic Bifidobacterium bifidum strain, against a galactooligosaccharide produced through the action of an industrial β-galactosidase and a placebo. DESIGN: Fifty-nine healthy human volunteers participated in this study. Initially, the effect of the matrix on the prebiotic properties of a commercially available galactooligosaccharide (7 g/d) was assessed during 7-d treatment periods with a 7-d washout period in between. During the second phase, 30 volunteers were assigned to a sequence of treatments (7 d) differing in the amount of the novel galactooligosaccharide (0, 3.6, or 7 g/d). Stools were recovered before and after each intervention, and bacteria numbers were determined by fluorescent in situ hybridization. RESULTS: Addition of the novel galactooligosaccharide mixture significantly increased the bifidobacterial population ratio compared with the placebo (P < 0.05), whereas 7 g/d of the novel galactooligosaccharide significantly increased the bifidobacterial ratio compared with the commercial galactooligosaccharide (P < 0.05). Moreover, a significant relation (P < 0.001) between the bifidobacteria proportion and the novel galactooligosaccharide dose (0, 3.6, and 7 g/d) was observed. This relation was similar to the effect of the novel galactooligosaccharide on the prebiotic index of each dose. CONCLUSIONS: This study showed that galactooligosaccharide mixtures produced with different β-galactosidases show different prebiotic properties and that, by using enzymes originating from bifidobacterial species, an increase in the bifidogenic properties of the prebiotic product is achievable.
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