An Analysis of the Role of the Indigenous Microbiota in Cholesterol Gallstone Pathogenesis

Background and Aims: Cholesterol gallstone disease is a complex process involving both genetic and environmental variables. No information exists regarding what role if any the indigenous gastrointestinal microbiota may play in cholesterol gallstone pathogenesis and whether variations in the microbiota can alter cholesterol gallstone prevalence rates. Methods: Genetically related substrains (BALB/cJ and BALB/cJBomTac) and (BALB/AnNTac and BALB/cByJ) of mice obtained from different vendors were compared for cholesterol gallstone prevalence after being fed a lithogenic diet for 8 weeks. The indigenous microbiome was altered in these substrains by oral gavage of fecal slurries as adults, by cross-fostering to mice with divergent flora at <1day of age or by rederiving into a germ-free state. Results: Alterations in the indigenous microbiome altered significantly the accumulation of mucin gel and normalized gallbladder weight but did not alter cholesterol gallstone susceptibility in conventionally housed SPF mice. Germ-free rederivation rendered mice more susceptible to cholesterol gallstone formation. This susceptibility appeared to be largely due to alterations in gallbladder size and gallbladder wall inflammation. Colonization of germ-free mice with members of altered Schaedler flora normalized the gallstone phenotype to a level similar to conventionally housed mice. Conclusions: These data demonstrate that alterations in the gastrointestinal microbiome may alter aspects of cholesterol gallstone pathogenesis and that in the appropriate circumstances these changes may impact cholesterol cholelithogenesis.National Institutes of Health (U.S.) (Grant T32OD010978)National Institutes of Health (U.S.) (Grant P30ES002109)National Institutes of Health (U.S.) (Grant R01AT004326

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

Contribución al conocimiento de los anofelinos argentinos

Facultad de Ciencias Naturales y Muse

Contribución al conocimiento de los anofelinos argentinos

Facultad de Ciencias Naturales y Muse

Crossfostering of mice leads to significant alterations in ASF361 and 457.

<p>ASF361 (A) and 457 (B) were quantified from a cohort (n = 5) of cross-fostered mice by real-time PCR. There were significant elevations in the colonization of these two bacteria in mice of Jackson origin crossfostered to Taconic mothers and significant decreases in Taconic pups crossfostered to Jackson mothers (*P<0.05) indicating effective alteration of the flora.</p

Germ-free mice are more susceptible to cholesterol cholelithogenesis (A) Normalized gallbladder weight (B) mucin gel score (C) Liquid crystal phase separation (D) cholesterol monohydrate crystal formation, (E) sandy stone formation and (F) cholesterol gallstone formation were analyzed after 8 weeks of lithogenic diet feeding.

<p>(A) Germ-free mice developed significantly increased normalized gallbladder weights compared to either conventional or ASF colonized mice (*P<0.05). Mucin gel score did not significantly differ among groups (all conventional and ASF mice developed mucin gel scores of “1”). (D–E) Germ-free mice developed significantly more cholesterol monohydrate (D, *P<0.05) and Sandy stones (E, *P<0.05) and had an non-significant increase in cholesterol gallstones (F).</p

Transfer of Taconic flora to Jackson mice leads to significant increases in ASF457 (A) and 361.

<p>ASF361 (A) and 457 (B) were quantified from a cohort of cross-faunated mice (n = 5) by real-time PCR. There were significant elevations in the colonization of these two bacteria in mice that were of Taconic origin or those which received Taconic flora (*P<0.05). Colonization of Taconic mice with Jackson flora did not significantly diminish the colonization by these organisms.</p

Biliary phenotype of genetically related BALB/cAnNTac (Tac) and BALB/cByJ (ByJ) and BALB/cJBomTac (Bom) and BALB/cJ (Jax) mice.

<p>(A) Normalized gallbladder weight (B) mucin gel score (C) Liquid crystal phase separation (D) cholesterol monohydrate crystal formation, (E) sandy stone formation and (F) cholesterol gallstone formation were analyzed after 8 weeks of lithogenic diet feeding. (A) Normalized gallbladder weight significantly differed between Tac mice and both ByJ and Jackson mice (*P<0.05). (B) Mucin gel score for both BALB/cJ and BALB/cJBomTac mice was significantly elevated compared to either Tac or ByJ mice (P<0.05). (C) Liquid crystal phase separation occurred in all animals studied. (D) Cholesterol monohydrate crystal formation occurred significantly more in BALB/cJ mice compared to both ByJ and Tac mice (*P<0.05). (E) Both BALB/cJ and BALB/cJBomTac mice compared to either Tac or ByJ mice displayed significantly increased sandy stone formation (*P<0.05). (F) Cholesterol gallstone formation was significantly increased in BALB/cJ and BALB/cJBomTac mice compared to Tac mice (*P<0.05).</p