MAPK-Activated Protein Kinase 2 Contributes to Clostridium difficile-Associated Inflammation

Clostridium difficile infection (CDI) results in toxin-induced epithelial injury and marked intestinal inflammation. Fecal markers of intestinal inflammation correlate with CDI disease severity, but regulation of the inflammatory response is poorly understood. Previous studies demonstrated that C. difficile toxin TcdA activates p38 kinase in tissue culture cells and mouse ilium, resulting in interleukin-8 (IL-8) release. Here, we investigated the role of phosphorylated mitogen-activated protein kinase (MAPK)-activated protein kinase (MK2 kinase, pMK2), a key mediator of p38-dependent inflammation, in CDI. Exposure of cultured intestinal epithelial cells to the C. difficile toxins TcdA and TcdB resulted in p38-dependent MK2 activation. Toxin-induced IL-8 and GROα release required MK2 activity. We found that p38 and MK2 are activated in response to other actin-disrupting agents, suggesting that toxin-induced cytoskeleton disruption is the trigger for kinase-dependent cytokine response. Phosphorylated MK2 was detected in the intestines of C. difficile-infected hamsters and mice, demonstrating for the first time that the pathway is activated in infected animals. Furthermore, we found that elevated pMK2 correlated with the presence of toxigenic C. difficile among 100 patient stool samples submitted for C. difficile testing. In conclusion, we find that MK2 kinase is activated by TcdA and TcdB and regulates the expression of proinflammatory cytokines. Activation of p38-MK2 in infected animals and humans suggests that this pathway is a key driver of intestinal inflammation in patients with CDI.     

Human MSH2 binds to trinucleotide repeat DNA structures associated with neurodegenerative diseases

The expansion of trinucleotide repeat sequences is associated with several neurodegenerative diseases. The mechanism of this expansion is unknown but may involve slipped-strand structures where adjacent rather than perfect complementary sequences of a trinucleotide repeat become paired. Here, we have studied the interaction of the human mismatch repair protein MSH2 with slipped-strand structures formed from a triplet repeat sequence in order to address the possible role of MSH2 in trinucleotide expansion. Genomic clones of the myotonic dystrophy locus containing disease-relevant lengths of (CTG)n x (CAG)n triplet repeats were examined. We have constructed two types of slipped-strand structures by annealing complementary strands of DNA containing: (i) equal numbers of trinucleotide repeats (homoduplex slipped structures or S-DNA) or (ii) different numbers of repeats (heteroduplex slipped intermediates or SI-DNA). SI-DNAs having an excess of either CTG or CAG repeats were structurally distinct and could be separated electrophoretically and studied individually. Using a band-shift assay, the MSH2 was shown to bind to both S-DNA and SI-DNA in a structure- specific manner. The affinity of MSH2 increased with the length of the repeat sequence. Furthermore, MSH2 bound preferentially to looped-out CAG repeat sequences, implicating a strand asymmetry in MSH2 recognition. Our results are consistent with the idea that MSH2 may participate in trinucleotide repeat expansion via its role in repair and/or recombination.      

A comparison of dietary behaviour in Central England and a French Mediterranean region

BJECTIVEe: The investigation involves comparison of dietary behaviour between UK and Mediterranean France by characterizing the pattern of the current French Mediterranean diet compared with the current British diet. DESIGN: The findings of two dietary surveys, one in the UK and one in France, are compared. An interviewer-administered questionnaire was used in both countries. Questions on food frequency were used to assess dietary behaviour, which were regrouped in the French survey to correspond with UK groupings. Dietary indices were constructed to describe dietary behaviour in relation to cancer recommendations for intake of fat, fibre, meat, fruit and vegetables. SETTING: The UK study was conducted in Leicestershire, central England and the French study was carried out in Hérault, southern France. Subjects: UK: n=418 subjects (57.9% female and 42.1% male; mean age=45.0 y); France: n=635 subjects (50.1% female and 40.9% male; mean age=49.8 y). Age range of both samples: 20-74 y. RESULTS: There were positive and negative trends in food consumption in each country. UK respondents reported eating more beans and pulses (P=0.000), less cheese (P=0. 000), red meat (P=0.001), and processed meats (P=0.000) than French respondents. However, on the negative side, they ate less fruit and vegetables (P=0.000), fish and poultry (P=0.000), cereals (P=0.000), and more sweets and chocolates (P=0.000), and cakes, pastries, biscuits and puddings (P=0.000). Women had healthier diets in both countries. CONCLUSIONS: Overall the southern French diet was healthier as French respondents scored significantly better for indices for fat, dietary fibre, fruit and vegetables (P=0.000 in all cases). However, the French sample scored poorer for the meat index (P=0.000). SPONSORSHIP: This study was supported by a grant from l'Association de la Recherche contre le Cancer (ARC) awarded to M Holdsworth.     

Survey of adolescents with severe intellectual handicap.

A diagnostic survey was undertaken of children aged 11 to 19 years in Tameside with severe learning difficulties (intelligence quotient less than or equal to 50). Eighty-two children were identified and their medical records reviewed. A specific diagnosis for the retardation was documented in 25 (30%) of the children, 18 of whom had Down''s syndrome. A probable aetiology or a disorder of unknown aetiology had been identified in a further 21 (26%) children. To confirm the existing diagnosis, identify new diagnoses, and offer genetic counselling, the parents of 63 children were offered detailed reassessment of their child. Fifty three children were reviewed, and a specific disorder identified in 25 out of 31 previously undiagnosed children. The most frequent diagnoses made were fragile X syndrome and Rett''s syndrome. On completion of the survey, 61 of the 82 children (74%) had a specific diagnosis or probable aetiology identified, 12 (15%) had associated disorders such as cerebral palsy, and in only nine of the 82 children (11%) were there no clues at all to the cause of their retardation.     

Fetal Renal Vein Thrombosis

Two cases of fetal renal vein thrombosis, diagnosed via maternal ultrasound scan are presented. One was associated with severe placental dysfunction and demonstrated haematuria and renal failure which resolved on day 10. The other followed an antepartum haemorrhage and resolved before the baby was born. The ultrasound showed, as transient findings, unilateral renal enlargement, thrombus protruding into the inferior vena cava, and mild fetal ascites. We suggest that fetal renal vein thrombosis may be more common than previously suspected, and warrants close monitoring of fetal well-being. Delivery should be considered if there is other evidence of fetal compromise, if the amount of peritoneal fluid suggests substantial haemorrhage, or if there is propagating thrombus in the inferior vena cava.     

Categorical versus dimensional models of mental disorder: the taxometric evidence

OBJECTIVE: To review studies of the categorical versus dimensional status of mental disorders that employ taxometric methodology. METHOD: A comprehensive qualitative review of all published taxometric studies of psychopathology. RESULTS: Categorical and dimensional models each receive well-replicated support for some groups of mental disorders. Studies favour categorical models for melancholia, eating disorders, pathological dissociation, and schizotypal and antisocial personality disorders. Dimensional models tend to be favoured for the broad neurotic spectrum--general depression, generalized anxiety, posttraumatic stress disorder--and for borderline personality disorder. CONCLUSIONS: Taxometric research clarifies the latent structure of psychopathology in ways that have implications for the classification, assessment, explanation and conceptualization of mental disorder.