150 research outputs found
Composition and stability of intestinal microbiota of healthy children within a Dutch population
No full textNumerous diseases linked to microbial imbalance can be traced back to childhood, illustrating the impact of the juvenile microbiota development from infancy toward adulthood. However, knowledge on this subject is currently very limited. The primary aim of this study was to characterize composition and short- and long-term stability of the intestinal microbiota in healthy children. Between November 2011 and June 2014, 61 children 2 to 18 yr of age from different areas in The Netherlands were included and instructed to collect fecal samples weekly, for 6 wk, and a follow-up sample after 18 mo. The intergenic spacer profiling technique (IS-pro) was used to analyze all available fecal samples. Microbial diversity was calculated by the Shannon diversity index and individual compositional stability by comparing all collection time points. Microbial stability varied per phylum (P < 0.0005), declined rapidly in a short time period, and subsequently stabilized on the long run with very gradual variation, leading to an overall compositional stability of 70% on average over a period of 18 mo. Higher species diversity was correlated to a higher overall compositional stability (P < 0.001). We observed an age-independent bacterial shared core consisting of a limited number of species. In conclusion, in this study, we showed that microbial composition stability in children varied per phylum, at both short-term and long-term intervals. Healthy children seem to share a microbiome core consisting of a limited number of species.-De Meij, T. G. J., Budding, A. E., de Groot, E. F. J., Jansen, F. M., Kneepkens, C. M. F., Benninga, M. A., Penders, J., van Bodegraven, A. A., Savelkoul, P. H. M. Composition and stability of intestinal microbiota of healthy children within a Dutch population
Agent-Based Modeling of Culture's Consequences for Trade
No full textIn this thesis, culture is interpreted as a property of a group of people who share the meaning they attach to symbols, have a common way of expressing their opinions and feelings, and share value systems to judge what is good or bad. The unwritten rules of a culture govern the interpretation of observations and emotions and how to react appropriately. The rules are embedded in an individuals’ mind, form childhood on, by interactions with group members. People often are not aware of differences between their own unwritten rules and those of people having a different cultural background. This may result in unwarranted distrust or unwarranted trust, with serious consequences for the future of relationships. Cultural differences are known to have their effects on trade. Signals that indicate benevolence and trustworthiness of a trade partner in one’s own culture may be interpreted differently by people having a different cultural background. Hofstede (2001) has identified five dimensions of cultural differences: ? Given ingroup relation with relatives and community members may have a different impact on professional relationships in different cultures. ? The impact of hierarchical relationships on the freedom of action of trade partners may be different across cultures. ? Some cultures are oriented toward cooperation and care-taking; others are oriented toward performance and competition. ? Xenophobia is a wide-spread phenomenon in some cultures, while people in other cultures may be more open to the unknown. ? In some cultures people are anxious to keep up their status and display their societal success, while in other cultures thrift and perseverance are seen as virtues. Cultural differences may have their effects in trade on the acceptability of potential partners, on progress and success of negotiations, and on the extent to which partners live up to the negotiated contracts. In a research project Meijer (2009) developed a gaming simulation to study the role of trust in supply networks of food products. The game is called the TRUST & TRACING game. In this game, the producers are informed about product quality. The other players either have to trust the suppliers on their quality statements, or they can have the products traced by an independent authority, but the latter will cost them a fee. In addition to the financial considerations, they must take into account that showing distrust may bring damage to their relationships. Experiments with human subjects in different cultures have shown that the considerations lead to different actions in different countries. It was also found that the inclination to grab an opportunity to defect was different across countries. The subject of this thesis is a computer simulation of the TRUST & TRACING GAME. The purposes of the computer simulation are: ? Validation of theories about, implemented in models of, the players’ behaviors ? testing of hypotheses about relations of rules of the game and parameters of individual players with aggregated game statistics, ? the design of useful game configurations to be played with human players. In the computer simulation the players’ rolls are realized by software agents. The questions which are answered in this thesis concern the modeling of culture’s consequences for the decisions taken by the agents. Such an agent is a computer program which simulates the behavior of human players. In a multi-agent simulation a group of software agents is acting and interacting simultaneously. Autonomy is an important property of software agents. The agents decide what to do; there is no central computer program that imposes decisions on them. Important functions of agents in the present simulation are to approach new potential trade partners, to negotiate about a transaction and to exchange proposals, and, when the negotiation has ended successfully, to exchange products, and to decide and request a trace to be performed. The agents’ decision mechanisms are implemented according to models and data available from scientific literature. To model the influence of culture on the decision making, an expert systems approach is taken, using the Synthetic Cultures according to Hofstede en Pedersen (1999). To develop an expert system, knowledge engineers represent knowledge about some domain of application as a set of rules that can be interpreted by a computer system. Since culture is considered as a set of rules, such an approach is a natural way to model it. The development of expert systems always is an interdisciplinary project. In this case the work of Geert Hofstede has been used and an expert on this work and on Synthetic Cultures has been involved in the formulation of the rules. Synthetic Cultures are imaginary cultures in which the effects of a single dimension of culture are emphasized, isolated from the effects of the other dimensions. The purpose is to make the differences related to that dimension teachable. In reality the differences may be less pronounced and may be mixed with differences related with the other dimensions. In this thesis an approach has been elaborated to compute the simultaneous effect of several dimensions. The approach is based on the principle of weak disjunction, which implies that, if several dimensions have a similar effect, only the strongest effects counts. For instance, if dimension A would have an effect of 75% and dimension B would have an effect of 25%, then their simultaneous effect would be 75%. Expert systems must at least have face validity. An expert in the domain of application mustaccept the decisions that the system produces and the reasoning that leads to these decisions, as being believable. For this purpose computations for specific cases can be made, of which the results are judged by the expert. Further, the results of sensitivity analysis can be judged by an expert. Sensitivity analysis of a model is performed by studying how model outputs vary in relation with systematic variation of input parameter. In addition to face validity, the model must be tested empirically. To that end outputs from gaming simulations with human participants can be compared with outputs from multi-agent simulations. For example, Meijer et al. (2006) found different outcomes from the TRUST & TRACING game between games played in the United States and in the Netherlands. Compared with the Dutch, American players are found to be more eager to buy top quality products, have a stronger inclination to opportunism, anticipate to a greater extent on their partners to defect, and have a stronger preference for quality certification. These differences where reproduced by the multi-agent simulation. The main question of this research is, whether an expert systems approach is feasible to develop a valid model of cultural differentiation in multi-agent simulations, to be applied in research with gaming simulations. The conclusions are: 1. Effects of dimensions of culture can be modeled as an expert system based on Synthetic Cultures. Modeling the simultaneous effects of several dimensions as an expert system proved not feasible: the complexity exceeded the intellectual powers of both expert and modeler. 2. The simultaneous effect of several dimensions can be modeled by weak disjunction of effects. The results have face validity and have empirically been verified for a limited number of cases. 3. Sensitivity analysis of this model is a complex undertaking if both cultural parameters and other parameters are simultaneously varied, because of the strong interactions between these types of parameters. When only the culture parameters are varied (with a fixed setting of the other parameters), or only the other parameters are varied (in a fixed cultural setting), straightforward sensitivity analysis is feasible. Furthermore, it was found that the sensitivity of aggregate model outputs may greatly differ from sensitivity of individual level outputs: parameters that do not affect the aggregate system performance, may affect results of individual agents. 4. This thesis proves that multi-agent simulation is a potent instrument to be used in research with gaming simulations, in particular for the purpose of validation of behavioral models. A problematic issue is, that similarity of the outputs of gaming simulations and multi-agent simulations is no sound proof that the agent correctly implements the human decision making mechanism. This issue is known as under-determination. A validation method is proposed, which builds on the model’s composed structure. Under-determination can be avoided by separate validation of the components in micro-games. The results of this research contribute to the methodology of cultural adaptation of intelligent software agents. This is relevant for the development of research instruments (like the TRUST & TRACING game), educational and training applications to make people aware of cultural differences, and affective human-computer interfaces in a globalizing world.MediamaticsElectrical Engineering, Mathematics and Computer Scienc
Altered Tryptophan Levels in Patients With Inflammatory Bowel Disease Owing to Colonic Leakage, Metabolism, or Malabsorption?
No full textSerial Microbiota Analysis after Fecal Microbiota Transplantation in a Child with Down's Syndrome
No full textFecal microbiota transplantation (FMT) is a very effective treatment for recurrent Clostridium difficile infection (CDI) in adults. However, there is a paucity of data on FMT in children and associated microbiome changes in this particular group. We describe a child with Down's syndrome and intracranial malignancy, who received FMT for recurrent CDI. Detailed microbiota analysis before and after FMT, and pre- and post-recurrence, linked to microbial communities in the donor feces showed that the patient developed a unique microbiota profile after FMT which was very stable over time despite CDI recurrence and subsequent fidaxomicin therapy. Bacteroidetes were stably acquired from donor feces, while Firmicutes, Actinobacteria, Fusobacteria, Verrucomicrobia, and Proteobacteria were unique to the patient. The diversity of microbiota of the patient increased from a Shannon diversity index of 2.08 pre-FMT to 3.12 post-FMT. Our findings underscore that patients with Down's syndrome may well tolerate and benefit from FMT even in a severely immunocompromised state
Ulcerative Gastritis and Esophagitis in Two Children with Sarcina ventriculi Infection
No full textSarcina ventriculi is a Gram-positive, obligate anaerobic coccus, with a characteristic morphology. Only 22 cases of human infections by this microorganism, including 7 in children, have been reported in literature so far. Affected subjects usually present with abdominal pain, nausea, vomiting, and delayed gastric emptying. However, life-threatening complications, like emphysematous gastritis and gastric perforation have also been described. Gastroparesis and gastric outlet obstruction have been considered as a potential etiologic factor. All pediatric cases described thus far presented with concomitant gastrointestinal pathology, such as Helicobacter pylori gastritis, celiac disease, infection with Giardia lamblia or Candida spp. Here, we report two children with S. ventriculi infection, in whom the diagnosis was established by typical histological findings in mucosal biopsies. The first child presented with hematemesis due to ulcerative esophagitis and gastritis, the second child with a history of esophageal stricture had ulcerative gastritis. Confirmation of S. ventriculi infection is feasible by molecular microbiota detection methods, since this microorganism cannot be detected by classical culture techniques. Prompt treatment with antibiotics could prevent life-threatening complications
Prediction of inflammatory bowel disease course based on fecal scent
No full textThe early prediction of changes in disease state allows timely treatment of patients with inflammatory bowel disease (IBD) to be performed, which improves disease outcome. The aim of this pilot study is to explore the potential of fecal volatile organic compound (VOC) profiles to predict disease course. In this prospective cohort, IBD patients were asked to collect two fecal samples and fill in a questionnaire at set intervals. Biochemically, active disease was defined by FCP ≥ 250 mg/g and remission was defined by FCP 100 mg/g. Clinically, active disease was defined by a Harvey Bradshaw Index (HBI) ≥ 5 for Crohn’s disease or by a Simple Clinical Colitis Activity Index (SCCAI) ≥ 3 for ulcerative colitis. Clinical remission was defined by an HBI 4 or SCCAI ≤ 2. Fecal VOC profiles were measured using gas chromatography-ion mobility spectrometry (GC-IMS). The fecal samples collected first were included for VOC analysis to predict disease state at the following collection. A total of 182 subsequently collected samples met the disease-state criteria. The fecal VOC profiles of samples displaying low FCP levels at the first measurements differed between patients preceding exacerbation versus those who remained in remission (AUC 0.75; p 0.01). Samples with FCP levels at the first time point displayed different VOC profiles in patients preceding remission compared with those whose disease remained active (AUC 0.86; p 0.01). Based on disease activity scores, there were no significant differences in any of the comparisons. Alterations in fecal VOC profiles preceding changes in FCP levels may be useful to detect disease-course alterations at an early stage. This could lead to earlier treatment, decreased numbers of complications, surgery and hospital admission
Intestinal lymphangiectasia—A novel finding in Van Maldergem syndrome challenging the role of lymphedema for the distinction from Hennekam syndrome
No full textFecal volatile organic compounds for early detection of colorectal cancer: where are we now?
No full textIntroduction: The fecal volatolome, which is composed of fecal volatile organic compounds (VOCs), seems to hold potential as non-invasive biomarker for the detection of colorectal cancer (CRC) and its precursor lesions advanced adenomas (AA). The potential of the fecal volatolome has been subject of various studies using either chemical analytical or pattern-recognition techniques. The available literature on the potential of the fecal volatolome as CRC and AA biomarker was reviewed. Methods: A systematic literature search was conducted in PubMed, Embase, the Cochrane Library, Google Scholar and ResearchGate using the following keywords: Colorectal Cancer, Advanced Adenoma, Volatile Organic Compound, Metabolome, Gas Chromatrography–Mass Spectrometry, Selected-Ion Flow-Tube Mass Spectrometry, eNose, and Fecal Biomarkers. Results: Eighty-eight titles or abstracts were identified from the search, of which 11 papers describing the potential of the fecal volatolome for CRC detection were selected. In these studies, different techniques were used for the headspace analyses of fecal VOCs, limiting the possibility to compare outcomes. Increased levels of amino acids and short chain fatty acids, and decreased levels of bile acids and polyol alcohols in the gas phase of feces were observed repeatedly. All selected papers reported high diagnostic value for the detection of both CRC and AA based on fecal VOCs. Conclusion: Based on the included studies, fecal VOC analyses seem promising for future screening of CRC and AA, with potentially improved test performances allowing for earlier detection of AA and CRC and consequently earlier initiation of treatment, possibly reducing morbidity and mortality rates next to lower rates of (unnecessary) colonoscopies
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