PECAM-1 supports leukocyte diapedesis by tension-dependent dephosphorylation of VE-cadherin

Leukocyte extravasation is an essential step during the immune response and requires the destabilization of endothelial junctions. We have shown previously that this process depends in vivo on the dephosphorylation of VE-cadherin-Y731. Here, we reveal the underlying mechanism. Leukocyte-induced stimulation of PECAM-1 triggers dissociation of the phosphatase SHP2 which then directly targets VE-cadherin-Y731. The binding site of PECAM-1 for SHP2 is needed for VE-cadherin dephosphorylation and subsequent endocytosis. Importantly, the contribution of PECAM-1 to leukocyte diapedesis in vitro and in vivo was strictly dependent on the presence of Y731 of VE-cadherin. In addition to SHP2, dephosphorylation of Y731 required Ca2+ -signaling, non-muscle myosin II activation, and endothelial cell tension. Since we found that β-catenin/plakoglobin mask VE-cadherin-Y731 and leukocyte docking to endothelial cells exert force on the VE-cadherin-catenin complex, we propose that leukocytes destabilize junctions by PECAM-1-SHP2-triggered dephosphorylation of VE-cadherin-Y731 which becomes accessible by actomyosin-mediated mechanical force exerted on the VE-cadherin-catenin complex.

Mental incapacity in hospitalised patients undergoing percutaneous endoscopic gastrostomy insertion

BACKGROUND & AIMS

Decisions to insert percutaneous endoscopic gastrostomy (PEG) tubes may be difficult because patients have serious underlying disease, and the procedure has associated risks. Patients may also lack mental capacity to consent to PEG insertion. This study aimed to prospectively determine the prevalence of mental incapacity in hospitalised patients undergoing PEG insertion.

METHODS

Mental capacity was assessed using the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) in 72 consecutive inpatients referred for PEG insertion. Cognitive function was measured using the Mini-Mental State Examination (MMSE). Sixty eight inpatients and 69 outpatients having diagnostic upper gastrointestinal (UGI) endoscopy were similarly studied.

RESULTS

Thirty nine of the PEG patients had suffered stroke, and none had a primary diagnosis of dementia. Seventy four % (53/72) of inpatients referred for PEG, 22% (15/68) of inpatients having UGI endoscopy, and 3% (2/69) of outpatients having UGI endoscopy, lacked mental capacity, p < 0.001. MMSE scores were normal in just 18% of inpatients having PEG, in 72% of inpatients having UGI endoscopy, and in 91% of outpatients having UGI endoscopy, p < 0.001.

CONCLUSION

Amongst inpatients undergoing PEG insertion there is a high prevalence (three-quarters patients) of mental incapacity to consent to this important intervention. Decisions have to be made on behalf of most inpatients referred for PEG insertion.

Diversity of Veillonella spp. from sound and carious sites in children

Detailed data on the distribution of Veillonella in caries-free and caries-active subjects are scarce. We hypothesized that the diversity of the genus would be lower in caries lesions than in plaque from caries-free individuals. The proportions of Veillonella were not significantly different in the two groups. All isolates (n = 1308) were genotyped by REP-PCR, and different genotypes (n = 170) were identified by 16S rRNA, dnaK, and rpoB sequencing. V. parvula, V. dispar, and V. atypica were in both groups, V. denticariosi only in caries lesions, and V. rogosae only from the caries-free individuals (p < 0.009). Lesions were more likely to harbor a single predominant species (p = 0.0018). The mean number of genotypes in the lesions was less than in the fissure (p < 0.001) or buccal (p = 0.011) sites. The Veillonella from caries-free sites were more diverse than those from caries lesions, and may be related to the acidic environment of caries lesions.

Microbiological assessment of occlusal brown-spot lesions in primary molars

Conventional cultural methods were used to compare the plaque flora and the level of infection of the dentine underlying 51 occlusal brown-spot lesions and 21 sound occlusal sites on the primary dentition. Freshly extracted primary molar teeth were used, and occlusal brown-spot lesions and sound occlusal sites were identified using laser fluorescence (LF) and clinical visual methods. A standardized plaque sample was taken from each site, and an LF score was recorded for one discrete site per tooth. The teeth were carefully opened at each predetermined site to determine the clinical status of the underlying dentine, and samples were collected using a sterile bur. The microbiota of the plaque and dentine samples were enumerated and identified. The mean LF scores for the sound sites and brown-spot lesions were 1.2 and 30.5 (p < 0.001), and all the sound sites exhibited hard sound dentine, but 6 out of 51 brown spots exhibited softened dentine. Overall there was no significant (p > 0.1) difference between the level of infection of the dentine of the sound and brown-spot sites, although some sites in the brown-spot lesions yielded high numbers of bacteria. However, the numbers of bacteria as log10(CFU per sample + 1) +/- SE recovered from the plaque above the brown-spot lesions were significantly greater than above the sound sites, i.e. 2.89 +/- 0.24 and 0.89 +/- 0.33, respectively. These data indicate that brown-spot lesions may be more plaque retentive than sound sites and that they are either arrested or arresting lesions, which may require preventive intervention.

Hepatic involvement with typhoid fever: a report of nine patients

Salmonella typhi has been reported to cause hepatic involvement. We studied nine patients with positive blood cultures in order to identify characteristic features of typhoid hepatitis which may help in early diagnosis. Patients who had an illness resembling enteric fever but negative cultures for Salmonella typhi were excluded. No specific clinical features were found consistently and liver function tests were widely variable. Other biochemical abnormalities occurred due to vomiting and renal involvement. Liver biopsy showed focal hepatocellular necrosis and non specific inflammation. Although most responded to conventional antibiotics, it was generally a delayed response. It is recommended that patients with fever greater than 38.5 degrees C and liver abnormalities should undergo blood, urine, stool and/or bone marrow cultures. Liver biopsy may help to differentiate typhoid hepatitis from acute viral hepatitis.