Uptake of Sialic Acid by Nontypeable Haemophilus influenzae Increases Complement Resistance through Decreasing IgM-Dependent Complement Activation.

Although nontypeable Haemophilus influenzae (NTHi) is a human-specific nasopharyngeal commensal bacterium, it also causes upper respiratory tract infections in children and lower respiratory tract infections in the elderly, resulting in frequent antibiotic use. The transition from symbiotic colonizing bacterium to opportunistic pathogen is not completely understood. Incorporation of sialic acids into lipooligosaccharides is thought to play an important role in bacterial virulence. It has been known for more than 25 years that sialic acids increase resistance to complement-mediated killing; however, the mechanism of action has not been elucidated thus far. Here, we provide evidence that growth of NTHi in the presence of sialic acids Neu5Ac and Neu5Gc decreases complement-mediated killing through abrogating the classical pathway of complement activation by preventing mainly IgM antibody binding to the bacterial surface. Therefore, strategies that interfere with uptake or incorporation of sialic acids into the lipooligosaccharide, such as novel antibiotics and vaccines, might be worth exploring to prevent or treat NTHi infections.

Should we assess clinical performance in single patient encounters or consistent behaviors of clinical performance over a series of encounters? A qualitative exploration of narrative trainee profiles.

BACKGROUND: A variety of tools have been developed to assess performance which typically use a single clinical encounter as a source for making competency inferences. This strategy may miss consistent behaviors. We therefore explored experienced clinical supervisors' perceptions of behavioral patterns that potentially exist in postgraduate general practice trainees expressed as narrative profiles to aid the grading of clinical performance. METHODS: We conducted semistructured interviews with clinical supervisors who had frequently observed clinical performance in trainees. Supervisors were asked to describe which behavioral patterns they had discerned in excellent and underperforming trainees, during different stages of training, in their careers as clinical supervisor. We analyzed the interviews using a grounded theory approach. RESULTS: The analysis resulted in a conceptual framework that distinguishes between desirable and undesirable narrative profiles. The framework consists of two dimensions: doctor-patient interaction and medical expertise. Personal values appear to be a moderating factor. CONCLUSIONS: According to experienced clinical supervisors, consistent behaviors do exist in GP trainees when observing clinical performance over time. The conceptual framework has to be validated by further observational studies to assess its potential for making robust and fair assessments of clinical performance and monitor the development of consultation performance over time.

Exopolysaccharide ß-(2,6)-levan-type fructans have a molecular-weight-dependent modulatory effect on Toll-like receptor signalling.

SCOPE: Fructans are a group of dietary fibers which are known to have many beneficial effects including immune-modulating effects. A family of fructans are ß-(2,6)-linked levan-type fructans that are known to serve as exopolysaccharides in the cell wall of many species of bacteria including commensal bacteria and probiotics. It is still largely unknown whether and how they can serve as immunomodulating molecules. RESULTS: Microbial ß-(2,6)-fructans were found to induce TLR-dependent activation of THP-1 cells, in a dose-dependent fashion. Low molecular weight (Mw), medium Mw and high Mw ß-(2,6)-fructans activated both TLR2 and 4 in a dose- and molecular weight-dependent fashion. In addition, it was found that ß-(2,6)-fructans were able to inhibit signalling of various TLRs with the strongest effect on TLR5 and 8, which were inhibited by all the ß-(2,6)-fructans in a dose- and molecular weight-dependent fashion. The final effect of this activation and inhibition of TLRs on cytokine responses in human dendritic cells (DCs) was minor which may be explained by the counter-activating effects of the different ß-(2,6)-linked levan-type fructans on inhibition of TLR signalling in the DCs. CONCLUSION: A mechanism by which exopolysaccharide levan ß-(2,6)-fructans can be immune-modulating is by impacting TLR signalling. This knowledge could lead to food in which exopolysaccharide levan ß-(2,6)-fructans are added for preventing disorders where TLR-signalling is modulated.

Exploring typologies of consultation performance using authentic clinical experiences to support learning and assessment in postgraduate medical training.

OBJECTIVE: To validate and refine typologies of consultation performance from previous research to identify learning needs associated with each typology. METHODS: We performed a qualitative study in a General Practice Specialty Training programme, using a two-stage design. First, we selected four exemplars from 80 videotaped consultations of 7 first-year and 6 third-year trainees that reflected the four typologies. We subsequently held individual interviews with clinical supervisors (N = 20) who observed these consultations to identify recurrent trainee behaviours. RESULTS: The 'doctor-patient interaction' dimension from previous research was specified to encompass relationship-building, exploring, structuring, and shared decision-making competencies. Medical expertise was a moderating factor. The attitude and consultation behaviours included in the typologies were validated and we formulated directions for learning based on learning needs identified per typology. CONCLUSION: Supervisors have a shared frame of reference for the behaviours reflecting proficient consultation performance. Serving as a developmental road map, all learning needs emphasised contextual adaptation, calling for an improved balance between patient-centred relationship building and application of medical expertise. PRACTICE IMPLICATIONS: By providing rich and tailored feedback on consultation performance, the refined typologies - albeit subject to additional refinement in future research - may promote the monitoring of individual competence development over time.

Efficient isolation of membrane-associated exopolysaccharides of four commercial bifidobacterial strains.

Bifidobacteria confer many health effects, such as fiber digestion, pathogen inhibition and immune system maturation, especially in the newborn infant. The bifidobacterial exopolysaccharides (EPS) are often associated with important health effects, but their thorough investigation is hampered by lack of knowledge of the EPS localization, which is important for efficient EPS isolation. Here we present a straightforward isolation procedure to obtain EPS of four commercial bifidobacterial strains (B. adolescentis, B. bifidum, B. breve, and B. infantis), that are localized at the cell membrane (evidenced using cryo-EM). This procedure can be applied to other bifidobacterial strains, to facilitate the easy isolation and purification for biological experiments and future application in nutraceuticals. In addition, we demonstrate structural differences in the EPS of the four bifidobacterial strains, in terms of monosaccharide composition and size, highlighting the potential of the isolated EPS for determining specific structure-activity effects of bifidobacteria.

Distinct fermentation of human milk oligosaccharides 3-FL and LNT2 and GOS/inulin by infant gut microbiota and impact on adhesion of Lactobacillus plantarum WCFS1 to gut epithelial cells.

Human milk oligosaccharides (hMOs) are unique bioactive components in human milk. 3-Fucosyllactose (3-FL) is an abundantly present hMO that can be produced in sufficient amounts to allow application in infant formula. Lacto-N-triaose II (LNT2) can be obtained by acid hydrolysis of lacto-N-neotetraose (LNnT). Both 3-FL and LNT2 have been shown to have health benefits, but their impact on infant microbiota composition and microbial metabolic products such as short-chain fatty acids (SCFAs) is unknown. To gain more insight in fermentability, we performed in vitro fermentation studies of 3-FL and LNT2 using pooled fecal microbiota from 12-week-old infants. The commonly investigated galacto-oligosaccharides (GOS)/inulin (9 : 1) served as control. Compared to GOS/inulin, we observed a delayed utilization of 3-FL, which was utilized at 60.3% after 36 h of fermentation, and induced the gradual production of acetic acid and lactic acid. 3-FL specifically enriched bacteria of Bacteroides and Enterococcus genus. LNT2 was fermented much faster. After 14 h of fermentation, 90.1% was already utilized, and production of acetic acid, succinic acid, lactic acid and butyric acid was observed. LNT2 specifically increased the abundance of Collinsella, as well as Bifidobacterium. The GOS present in the GOS/inulin mixture was completely fermented after 14 h, while for inulin, only low DP was rapidly utilized after 14 h. To determine whether the fermentation might lead to enhanced colonization of commensal bacteria to gut epithelial cells, we investigated adhesion of the commensal Lactobacillus plantarum WCFS1 to Caco-2 cells. The fermentation digesta of LNT2 collected after 14 h, 24 h, and 36 h, and GOS/inulin after 24 h of fermentation significantly increased the adhesion of L. plantarum WCFS1 to Caco-2 cells, while 3-FL had no such effect. Our findings illustrate that fermentation of hMOs is very structure-dependent and different from the commonly applied GOS/inulin, which might lead to differential potencies to stimulate adhesion of commensal cells to gut epithelium and consequent microbial colonization. This knowledge might contribute to the design of tailored infant formulas containing specific hMO molecules to meet the need of infants during the transition from breastfeeding to formula.

A meta-analysis on depression and subsequent cancer risk.

BACKGROUND: The authors tested the hypothesis that depression is a possible factor influencing the course of cancer by reviewing prospective epidemiological studies and calculating summary relative risks. METHODS: Studies were identified by computerized searches of Medline, Embase and PsycINFO. as well as manual searches of reference lists of selected publications. Inclusion criteria were cohort design, population-based sample, structured measurement of depression and outcome of cancer known for depressed and non-depressed subjects RESULTS: Thirteen eligible studies were identified. Based on eight studies with complete crude data on overall cancer, our summary relative risk (95% confidence interval) was 1.19 (1.06-1.32). After adjustment for confounders we pooled a summary relative risk of 1.12 (0.99-1.26).No significant association was found between depression and subsequent breast cancer risk, based on seven heterogeneous studies, with or without adjustment for possible confounders. Subgroup analysis of studies with a follow-up of ten years or more, however, resulted in a statistically significant summary relative risk of 2.50 (1.06-5.91).No significant associations were found for lung, colon or prostate cancer. CONCLUSION: This review suggests a tendency towards a small and marginally significant association between depression and subsequent overall cancer risk and towards a stronger increase of breast cancer risk emerging many years after a previous depression.

The Hematopoietic Transcription Factors RUNX1 and ERG Prevent AML1-ETO Oncogene Overexpression and Onset of the Apoptosis Program in t(8;21) AMLs.

The t(8;21) acute myeloid leukemia (AML)-associated oncoprotein AML1-ETO disrupts normal hematopoietic differentiation. Here, we have investigated its effects on the transcriptome and epigenome in t(8,21) patient cells. AML1-ETO binding was found at promoter regions of active genes with high levels of histone acetylation but also at distal elements characterized by low acetylation levels and binding of the hematopoietic transcription factors LYL1 and LMO2. In contrast, ERG, FLI1, TAL1, and RUNX1 bind at all AML1-ETO-occupied regulatory regions, including those of the AML1-ETO gene itself, suggesting their involvement in regulating AML1-ETO expression levels. While expression of AML1-ETO in myeloid differentiated induced pluripotent stem cells (iPSCs) induces leukemic characteristics, overexpression increases cell death. We find that expression of wild-type transcription factors RUNX1 and ERG in AML is required to prevent this oncogene overexpression. Together our results show that the interplay of the epigenome and transcription factors prevents apoptosis in t(8;21) AML cells.