Magnetic ordering in an organic polymer.

We describe preparation and magnetic properties of an organic pi-conjugated polymer with very large magnetic moment and magnetic order at low temperatures. The polymer is designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S = 2 and, cross-linking S = (1/2) modules, which permits large net S values for either ferromagnetic or antiferromagnetic exchange couplings between the modules. In the highly cross-linked polymer, an effective magnetic moment corresponding to an average S of about 5000 and slow reorientation of the magnetization by a small magnetic field (less than or equal to 1 oersted) below a temperature of about 10 kelvin are found. Qualitatively, this magnetic behavior is comparable to that of insulating spin glasses and blocked superparamagnets.

Impact of the diagnosis and treatment of cancer on the course of inflammatory bowel disease.

BACKGROUND: The effects of extra-intestinal cancer on the course of inflammatory bowel disease (IBD) are poorly understood. AIM: To evaluate the impact of cancer and its management on IBD outcomes. METHODS: A total 80 IBD patients (51 Crohn's disease, 29 ulcerative colitis; 33 men, median age at cancer diagnosis 48yrs) diagnosed with extra-intestinal cancer were selected from a prospective database. IBD activity and therapeutic requirements (assessed year-by-year) were compared before and after cancer diagnosis, with a control group of patients without cancer matched for gender, birth date, date of IBD diagnosis and IBD phenotype. RESULTS: Paired comparisons of the consecutive periods before and after cancer diagnosis did not show significant changes in median (IQR) percentages of years with active disease (27% [0-50] vs. 19% [0-53]), while the proportion of patient-years on any immunosuppressant remained stable (26% vs. 28%). Chemotherapy had no significant effect on IBD activity. Compared to controls, patients with cancer had a similar IBD activity and use of anti-TNF, but less use of immunomodulators (19% vs. 25%, p<0,001) and an increased rate of surgery (4% vs. 2.5%, p<0,05). Individual variations in IBD activity after cancer diagnosis were not significantly different in patients with cancer and their matched controls. CONCLUSION: Occurrence of extra-intestinal cancer impacts IBD therapeutic management, with a trend towards less use of immunomodulators and more surgery. In the long-term, cancer diagnoses and treatments do not modify IBD outcomes.

Increase in fecal primary bile acids and dysbiosis in patients with diarrhea-predominant irritable bowel syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) is a multifactorial disease for which a dysbiosis of the gut microbiota has been described. Bile acids (BA) could play a role as they are endogenous laxatives and are metabolized by gut microbiota. We compared fecal BA profiles and microbiota in healthy subjects (HS) and patients with diarrhea-predominant IBS (IBS-D), and we searched for an association with symptoms. METHODS: Clinical features and stool samples were collected in IBS-D patients and HS. Fecal BA profiles were generated using HPLC coupled to tandem mass spectrometry. The fecal microbiota composition was assessed by q-PCR targeting dominant bacterial groups and species implicated in BA transformation. KEY RESULTS: Fourteen IBS-D patients and 18 HS were included. The two groups were comparable in terms of age and sex. The percentage of fecal primary BA was significantly higher in IBS-D patients than in HS, and it was significantly correlated with stool consistency and frequency. Fecal counts of all bacteria, lactobacillus, coccoides, leptum and Faecalibacterium prausnitzii were similar. There was a significant increase of Escherichia coli and a significant decrease of leptum and bifidobacterium in IBS-D patients. CONCLUSIONS & INFERENCES: We report an increase of primary BA in the feces of IBS-D patients compared to HS, correlated with stool consistency and frequency. A dysbiosis of different bacterial groups was detected, some of them involved in BA transformation. As the gut microbiota is the exclusive pathway to transform primary into secondary BA, this suggests a functional consequence of dysbiosis, leading to lower BA transformation.