Properdin: binding to C3b and stabilization of the C3b-dependent C3 convertase

A function of P in the alternative complement pathway is to prolong the first order decay of the hemolytic sites on EAC43B in a dose-dependent manner. As the number of initial convertase sites is not changed, even when activated properdin (P) increases the t1/2 10-fold or more, P acts to stabilize rather than to uncover additional sites. P binds to EAC43 to generate EAC43P in a reaction that proceeds slightly more rapidly at 15 degrees C than at 0 degrees C, but reaches the same plateau and does not require divalent cations. The presence of P on EAC43P not only stabilizes the convertase subsequently formed on that cell, but, alternatively, permits transfer to convertase sites on other cells with the stability of the recipient intermediate being dependent on the P available for transfer. The capacity of P to bind to C3b and stabilize C3B contrasts with the inhibitory effect of the C3b inactivator on formation of this amplification convertase.     

A study of adaptive responses in cell signaling in migraine and cluster headache: correlations between headache type and changes in gene expression

The project was an investigation into whether changes in the expression of G-proteins underlie altered cell signaling in migraine and cluster headache. The basis for this assumption is that altered physiological responses are seen in migraineurs and that differences in cell signaling are detected biochemically in various cell types isolated from peripheral blood. Levels of three G-protein mRNAs—Gsα, Giα, and Gqα were quantified in lymphocytes from clinically well-defined migraine and cluster headache patients and correlated with headache type and influence of drug treatment. Giα mRNA was reduced by 50% in all migraine patients compared with control subjects; similarly in patients with or without aura, in patients with a migraine headache at the time of sampling, and patients in a quiescent state. No reduction in the levels of Gsα or Gqα mRNA were seen in migraine patients. A smaller reduction was seen in cluster headache patients, most marked in those without medication. Levels of Gsα. mRNA were significantly reduced in cluster headache patients compared with migraine patients. The marked down-regulation of Giα mRNA in migraine, whether quiescent or acute, indicates either an adaptive response to headache in this group of patients or that low levels of Giα mRNA make individuals more susceptible to migraine.     

PROPERDIN FACTOR D: CHARACTERIZATION OF ITS ACTIVE SITE AND ISOLATION OF THE PRECURSOR FORM

The activity of properdin factor D was measured by the generation of the hemolytically active cellular intermediate, EAC43B(D), bearing the C3b-dependent alternate pathway C3 convertase. Treatment of factor D with DFP prevented formation of EAC43B(D); thus, a serine esterase is essential for the generation of the alternate pathway C3 convertase, a situation analogous to the role of C1 in the formation of the classical C3 convertase, C42. The definition of factor D as a serine esterase prompted a search for its proenzyme form, and resulted in the chromatographic isolation from plasma of a single peak of trypsin-inducible factor D activity, distinct from activated factor D. Analytical gel filtration indicated an apparent mol wt of 25,000. This protein from which trypsin elaborated factor D activity, as assessed by the formation of EAC43B(D), the generation of the CoVF-dependent C3 convertase, and the cleavage of factor B in the presence of C3b, was designated "precursor factor D." The DFP resistance of precursor factor D, and the susceptibility of its trypsin-activated form to inactivation by DFP is analogous to the behavior of other plasma serine esterases, including C1.     

Clinical Impact of Tumour Involvement of the Anastomotic Doughnut in Oesophagogastric Cancer Surgery

INTRODUCTION

Published colorectal cancer surgery data suggest no role for the analysis of the anastomotic doughnuts following anterior resection. The usefulness of routine histological analysis of the upper gastrointestinal doughnut is not clear. Our study assessed the impact of cancer involvement of the doughnut on clinical practice. Factors associated with doughnut involvement and the effect on patients'' survival were also analysed.

PATIENTS AND METHODS

The clinicopathological details of 462 patients who underwent potentially curative oesophagogastrectomy for cancer with a stapled anastomosis between 1994 and 2006 in two specialist centres were retrospectively analysed. Univariate, multivariate and survival analyses were carried out.

RESULTS

Approximately 5% of doughnuts (22 of 462) were histologically involved with cancer. Microscopic involvement of the proximal resection margin, local lymph node metastasis and lymphatic invasion within the main resected specimen were independently associated with doughnut involvement (all P < 0.05). However, these three factors taken together failed to predict doughnut involvement. Doughnut involvement was an independent adverse prognostic factor for overall survival (P = 0.0013).

CONCLUSIONS

In contrast to findings in colorectal surgery, doughnut involvement with cancer appears to have useful prognostic information following oesophagogastrectomy. Routine histological analysis of upper gastrointestinal doughnuts is justified. Doughnut involvement could potentially strengthen the indications for adjuvant therapy in the future.     

Minor physical anomalies across ethnic groups in a first episode psychosis sample

Minor physical anomalies (MPAs) are more prevalent amongst individuals with psychosis, supporting a neurodevelopmental model for psychotic disorders. The aim of this study was to investigate the possibility that neurodevelopmental adversity contributes to the excess of psychosis found in some ethnic groups in the UK. Subjects with first onset psychosis and healthy neighbourhood controls were enrolled in the AESOP study in South East London and Nottingham between 1997 and 1999. MPA rates were estimated in four broad ethnic groupings (White, African Caribbean, Black African and Other). Patients (n=245) had a higher mean total MPA score than healthy controls (n=158). This held true across each of the four ethnic groupings. The results of this study suggest that neurodevelopmental factors play a role in the aetiology of psychosis across all ethnic groups.     

Angiogenesis and blood vessel stability in inflammatory arthritis

Objective

To assess blood vessel stability in inflammatory synovial tissue (ST) and to examine neural cell adhesion molecule (NCAM), oxidative DNA damage, and hypoxia in vivo.

Methods

Macroscopic vascularity and ST oxygen levels were determined in vivo in patients with inflammatory arthritis who were undergoing arthroscopy. Vessel maturity/stability was quantified in matched ST samples by dual immunofluorescence staining for factor VIII (FVIII)/α‐smooth muscle actin (α‐SMA). NCAM and 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxodG) were examined by immunohistochemistry. Angiogenesis was assessed in vitro, using human dermal endothelial cells (HDECs) in a Matrigel tube formation assay.

Results

A significant number of immature vessels (showing no pericyte recruitment) was observed in tissue from patients with inflammatory arthritis (P < 0.001), in contrast to osteoarthritic and normal tissue, which showed complete recruitment of pericytes. Low in vivo PO ₂ levels in the inflamed joint (median [range] 22.8 [3.2–54.1] mm Hg) were inversely related to increased macroscopic vascularity (P < 0.04) and increased microscopic expression of FVIII and α‐SMA (P < 0.04 and P < 0.03, respectively). A significant proportion of vessels showed focal expression of NCAM and strong nuclear 8‐oxodG expression, implicating a loss of EC–pericyte contact and increased DNA damage, levels of which were inversely associated with low in vivo PO ₂ (P = 0.04 for each comparison). Circulating cells were completely negative for 8‐oxodG. Exposure of HDEC to 3% O₂ (reflecting mean ST in vivo measurements) significantly increased EC tube formation (P < 0.05).

Conclusion

Our findings indicate the presence of unstable vessels in inflamed joints associated with hypoxia, incomplete EC–pericyte interactions, and increased DNA damage. These changes may further contribute to persistent hypoxia in the inflamed joint to further drive this unstable microenvironment.

     

Colitis and cancer: a tale of inflammatory cells and their cytokines

Chronic inflammatory disorders are often associated with an increased cancer risk. A particularly striking example of the chronic inflammation-cancer link is seen in inflammatory bowel disease, in which chronic colitis or persistent inflammation in the colon is associated with elevated risk of colorectal cancer. Animal models exploring the mechanisms by which inflammation increases the risk of colon cancer have shown that inflammatory cells, through the effects of the cytokines they produce, have a major role in promoting neoplastic transformation. In this issue of the JCI, Popivanova and colleagues demonstrate that TNF-alpha, through its effects on the immune system, plays a critical role in promoting neoplastic transformation in this setting (see the related article beginning on page 560). Importantly, the study also provides evidence that anti-TNF-alpha therapies, which are currently in clinical use, may interrupt the process.