Herpes Simplex Virus 1 Glycoprotein B from a Hyperfusogenic Virus Mediates Enhanced Cell-Cell Fusion

Herpes simplex virus 1 (HSV-1) causes significant morbidity and death in humans worldwide. Herpes simplex virus 1 has a complex fusion mechanism that is incompletely understood. The HSV-1 strain ANG has notable fusion and entry activities that distinguish it from wild type. HSV-1 ANG virions fused with the Vero cell surface at 4 °C and also entered cells more efficiently at 15 °C, relative to wild type HSV-1 strain KOS virions, consistent with a hyperfusogenic phenotype. Understanding the molecular basis for the unique entry and fusion activities of HSV-1 strain ANG will help decipher the HSV fusion reaction and entry process. Sequencing of HSV-1 ANG genes revealed multiple changes in gB, gC, gD, gH, and gL proteins relative to wild type HSV-1 strains. The ANG UL45 gene sequence, which codes for a non-essential envelope protein, was identical to wild type KOS. HSV-1 ANG gB, gD, and gH/gL were necessary and sufficient to mediate cell-cell fusion in a virus-free reporter assay. ANG gB, when expressed with wild type KOS gD and gH/gL, increased membrane fusion, suggesting that ANG gB has hyperfusogenic cell-cell fusion activity. Replacing the KOS gD, gH, or gL with the corresponding ANG alleles did not enhance cell-cell fusion. The novel mutations in the ANG fusion and entry glycoproteins provide a platform for dissecting the cascade of interactions that culminate in HSV fusion and entry.

Membrane fusion activity of herpes simplex virus 1 glycoproteins from a hyperfusogenic virus

Herpes simplex virus 1 (HSV-1) causes significant morbidity and death in humans worldwide. Herpes simplex virus 1 has a complex fusion mechanism that is incompletely understood. The HSV-1 strain ANG has notable fusion and entry activities that distinguish it from wild type. HSV-1 ANG virions fused with the Vero cell surface at 4°C and also entered cells more efficiently at 15°C relative to wild type virions, consistent with a hyperfusogenic phenotype. Understanding the molecular basis for the unique entry and fusion activities of HSV-1 strain ANG will help decipher the HSV fusion reaction and entry process. Sequencing of HSV-1 ANG genes revealed multiple changes in gB, gC, gD, gH, and gL proteins relative to wild type HSV-1 strains. The ANG UL45 gene sequence, which codes for a non-essential envelope protein, was identical to wild type. HSV-1 ANG gB, gD, and gH/gL were necessary and sufficient to mediate cell-cell fusion in a virus-free reporter assay. ANG gB, when expressed with wild type gD and gH/gL, increased membrane fusion, suggesting that ANG gB has hyperfusogenic cell-cell fusion activity. Replacing the wild type gD, gH, or gL with the corresponding ANG alleles did not enhance cell-cell fusion. Wild type gC is proposed to facilitate fusion and entry into epithelial cells by optimizing conformational changes in the fusion protein gB. ANG gC substitution or addition also had no effect on cell-cell fusion. The novel mutations in the ANG fusion and entry glycoproteins provide a platform for dissecting the cascade of interactions that culminate in HSV fusion and entry.

Plasma and rectal mucosal oxylipin levels during aspirin and eicosapentaenoic acid treatment in the seAFOod polyp prevention trial

BACKGROUND

Aspirin and eicosapentaenoic acid (EPA) have colorectal polyp prevention activity, alone and in combination. This study measured levels of plasma and rectal mucosal oxylipins in participants of the seAFOod 2 × 2 factorial, randomised, placebo-controlled trial, who received aspirin 300 mg daily and EPA 2000 mg free fatty acid, alone and in combination, for 12 months.

METHODS

Resolvin (Rv) E1, 15-epi-lipoxin (LX) A₄ and respective precursors 18-HEPE and 15-HETE (with chiral separation) were measured by ultra-high performance liquid chromatography-tandem mass spectrometry in plasma taken at baseline, 6 months and 12 months, as well as rectal mucosa obtained at trial exit colonoscopy at 12 months, in 401 trial participants.

RESULTS

Despite detection of S- and R- enantiomers of 18-HEPE and 15-HETE in ng/ml concentrations, RvE1 or 15‑epi-LXA₄ were not detected above a limit of detection of 20 pg/ml in plasma or rectal mucosa, even in individuals randomised to both aspirin and EPA. We have confirmed in a large clinical trial cohort that prolonged (12 months) treatment with EPA is associated with increased plasma 18-HEPE concentrations (median [inter-quartile range] total 18-HEPE 0.51 [0.21-1.95] ng/ml at baseline versus 0.95 [0.46-4.06] ng/ml at 6 months [P<0.0001] in those randomised to EPA alone), which correlate strongly with respective rectal mucosal 18-HEPE levels (r = 0.82; P<0.001), but which do not predict polyp prevention efficacy by EPA or aspirin.

CONCLUSION

Analysis of seAFOod trial plasma and rectal mucosal samples has not provided evidence of synthesis of the EPA-derived specialised pro-resolving mediator RvE1 or aspirin-trigged lipoxin 15‑epi-LXA₄. We cannot rule out degradation of individual oxylipins during sample collection and storage but readily measurable precursor oxylipins argues against widespread degradation.

Molecular Modeling Predicts Novel Antibody Escape Mutations in the Respiratory Syncytial Virus Fusion Glycoprotein

Monoclonal antibodies are increasingly used for the prevention and/or treatment of viral infections. One caveat of their use is the ability of viruses to evolve resistance to antibody binding and neutralization. Computational strategies to identify viral mutations that may disrupt antibody binding would leverage the wealth of viral genomic sequence data to monitor for potential antibody-resistant mutations. The respiratory syncytial virus is an important pathogen for which monoclonal antibodies against the fusion (F) protein are used to prevent severe disease in high-risk infants. In this study, we used an approach that combines molecular dynamics simulations with FoldX to estimate changes in free energy in F protein folding and binding to the motavizumab antibody upon each possible amino acid change. We systematically selected 8 predicted escape mutations and tested them in an infectious clone. Consistent with our F protein stability predictions, replication-effective viruses were observed for each selected mutation. Six of the eight variants showed increased resistance to neutralization by motavizumab. Flow cytometry was used to validate the estimated (model-predicted) effects on antibody binding to F. Using surface plasmon resonance, we determined that changes in the on-rate of motavizumab binding were associated with the reduced affinity for two novel escape mutations. Our study empirically validated the accuracy of our molecular modeling approach and emphasized the role of biophysical protein modeling in predicting viral resistance to antibody-based therapeutics that can be used to monitor the emergence of resistant viruses and to design improved therapeutic antibodies. IMPORTANCE Respiratory syncytial virus (RSV) causes severe disease in young infants, particularly those with heart or lung diseases or born prematurely. Because no vaccine is currently available, monoclonal antibodies are used to prevent severe RSV disease in high-risk infants. While it is known that RSV evolves to avoid recognition by antibodies, screening tools that can predict which changes to the virus may lead to antibody resistance are greatly needed.

Screen-detected colorectal cancers are associated with an improved outcome compared with stage-matched interval cancers

Background:

Colorectal cancers (CRCs) detected through the NHS Bowel Cancer Screening Programme (BCSP) have been shown to have a more favourable outcome compared to non-screen-detected cancers. The aim was to identify whether this was solely due to the earlier stage shift of these cancers, or whether other factors were involved.

Methods:

A combination of a regional CRC registry (Northern Colorectal Cancer Audit Group) and the BCSP database were used to identify screen-detected and interval cancers (diagnosed after a negative faecal occult blood test, before the next screening round), diagnosed between April 2007 and March 2010, within the North East of England. For each Dukes' stage, patient demographics, tumour characteristics, and survival rates were compared between these two groups.

Results:

Overall, 322 screen-detected cancers were compared against 192 interval cancers. Screen-detected Dukes' C and D CRCs had a superior survival rate compared with interval cancers (P=0.014 and P=0.04, respectively). Cox proportional hazards regression showed that Dukes' stage, tumour location, and diagnostic group (HR 0.45, 95% CI 0.29–0.69, P<0.001 for screen-detected CRCs) were all found to have a significant impact on the survival of patients.

Conclusions:

The improved survival of screen-detected over interval cancers for stages C and D suggest that there may be a biological difference in the cancers in each group. Although lead-time bias may have a role, this may be related to a tumour's propensity to bleed and therefore may reflect detection through current screening tests.

The omega-3 polyunsaturated fatty acid eicosapentaenoic acid inhibits mouse MC-26 colorectal cancer cell liver metastasis via inhibition of PGE2-dependent cell motility

BACKGROUND AND PURPOSE

The omega-3 polyunsaturated fatty acid (PUFA) eicosapentaenoic acid (EPA) has antineoplastic activity at early stages of colorectal carcinogenesis, relevant to chemoprevention of colorectal cancer (CRC). We tested the hypothesis that EPA also has anti-CRC activity at later stages of colorectal carcinogenesis, relevant to treatment of metastatic CRC, via modulation of E-type PG synthesis.

EXPERIMENTAL APPROACH

A BALB/c mouse model, in which intrasplenic injection of syngeneic MC-26 mouse CRC cells leads to development of liver metastases, was used. Dietary EPA was administered in the free fatty acid (FFA) form for 2 weeks before and after ultrasound-guided intrasplenic injection of 1 × 10(6) MC-26 cells (n= 16 each group).

KEY RESULTS

Treatment with 5% (w w(-1)) EPA-FFA was associated with a reduced MC-26 mouse CRC cell liver tumour burden compared with control animals (median liver weight 1.03 g vs. 1.62 g; P < 0.034). Administration of 5% EPA-FFA was also linked to a significant increase in tumour EPA incorporation and lower intratumoural PGE(2) levels (with concomitant increased production of PGE(3)). Liver tumours from 5% EPA-FFA- treated mice demonstrated decreased 5-bromo-2-deoxyuridine-positive CRC cell proliferation and reduced phosphorylated ERK 1/2 expression at the invasive edge of tumours. A concentration-dependent reduction in MC-26 CRC cell Transwell® migration following EPA-FFA treatment (50-200 µM) in vitro was rescued by exogenous PGE(2) (10 µM) and PGE(1)-alcohol (1 µM).

CONCLUSIONS AND IMPLICATIONS

EPA-FFA inhibits MC-26 CRC cell liver metastasis. EPA incorporation is associated with a 'PGE(2) to PGE(3) switch' in liver tumours. Inhibition of PGE(2)-EP(4) receptor-dependent CRC cell motility probably contributes to the antineoplastic activity of EPA.

Omega-3 polyunsaturated fatty acids for the treatment and prevention of colorectal cancer

Omega (ω)-3 polyunsaturated fatty acids (PUFAs) are naturally occurring substances that are well tolerated and have been used extensively for the prevention of cardiovascular disease. More recently, ω-3 PUFAs have been recognised to have anticancer activity. There is also evidence suggesting improved efficacy and/or tolerability of conventional cancer chemotherapy when administered with ω-3 PUFAs. The purpose of this review is to (i) describe the mechanisms by which ω-3 PUFAs are thought to have antineoplastic activity, (ii) review published preclinical and clinical studies that support anti-colorectal cancer activity and (iii) summarise current clinical trials investigating the potential therapeutic role(s) of ω-3 PUFAs at different stages of colorectal carcinogenesis, from adenoma (polyp) prevention to treatment of established malignant disease and prevention of cancer recurrence.

Lack of interleukin-4 receptor alpha chain-dependent signalling promotes azoxymethane-induced colorectal aberrant crypt focus formation in Balb/c mice

Interleukin (IL)-4 receptor (IL-4R) alpha chain-dependent signalling by IL-4 and IL-13 promotes tumour growth and metastasis in mouse models of colorectal cancer. However, the role of IL-4R alpha-dependent signalling during the early, pre-malignant stages of colorectal carcinogenesis has not been investigated. Therefore, we investigated the effect of deletion of the IL-4R alpha gene on azoxymethane-induced colorectal aberrant crypt focus (ACF) multiplicity and size in Balb/c mice. IL-4R alpha(-/-) mice developed significantly more ACFs [median 8, inter-quartile range (IQR) 4-11.5; n = 9] than wild-type (WT) animals (median 4, IQR 1-6; n = 9; p = 0.04, Mann-Whitney U-test). There were significantly higher levels of IL-4 in serum from azoxymethane- and sham-treated IL-4R alpha(-/-) mice than WT animals, but no difference in serum IL-13 levels. In the absence of functional IL-4Rs, IL-13 can also signal via the IL-13R alpha2 receptor, leading to induction of transforming growth factor (TGF) beta, which has pro-tumourigenic activity at early stages of intestinal tumourigenesis. We found that mucosal TGFbeta mRNA levels and intestinal epithelial cell TGFbeta immunoreactivity were significantly higher in IL-4R alpha(-/-) mice than in WT animals. In summary, IL-4R alpha-dependent signalling has a protective, anti-neoplastic role during the post-initiation phase of azoxymethane-induced colorectal carcinogenesis in Balb/c mice. Our data should prompt thorough investigation of the role of IL-4R alpha-dependent signalling during human colorectal carcinogenesis, particularly as antagonism of IL-4R signalling represents a therapeutic strategy for asthma and other allergic diseases.

Abnormal T cell differentiation persists in patients with rheumatoid arthritis in clinical remission and predicts relapse

OBJECTIVES

An abnormal CD4+ T cell subset related to inflammation exposure (inflammation-related cells, IRC) has been identified in rheumatoid arthritis (RA). Patients with inflammatory and non-inflammatory diseases were used to examine the relationship between inflammation and this T cell subset in vivo.

METHODS

Blood was collected from healthy controls and patients with RA (active disease or in clinical remission), Crohn's disease and osteoarthritis. IRC and chemokine receptors were quantified by flow cytometry. Thymic activity and apoptotic factors were measured by real-time polymerase chain reaction. Circulating cytokines were measured by enzyme-linked immunosorbent assay. CXCR4 and SDF1 in synovial biopsies were measured using immunohistochemistry.

RESULTS

IRC were identified in patients with RA (p<0.0001) and Crohn's disease (p = 0.005), but not in those with osteoarthritis. In RA in remission, IRC persisted (p<0.001). In remission, hyperproliferation of IRC was lost, chemokine receptor expression was significantly lowered (p<0.007), Bax expression dropped significantly (p<0.001) and was inversely correlated with IRC (rho = -0.755, p = 0.03). High IRC frequency in remission was associated with relapse within 18 months (OR = 6.4, p<0.001) and a regression model predicted 72% of relapse.

CONCLUSIONS

These results suggest a model in which, despite the lack of systemic inflammation, IRC persist in remission, indicating that IRC are an acquired feature of RA. They have, however, lost their hyper-responsiveness, acquired a potential for survival, and no longer express chemokine receptors. IRC persistence in remission confirms their important role in chronic inflammation as circulating precursors of pathogenic cells. This was further demonstrated by much higher incidence of relapse in patients with high IRC frequency in remission.

Prostaglandin E2-EP4 receptor signalling promotes tumorigenic behaviour of HT-29 human colorectal cancer cells

The predominant product of cyclooxygenase (COX) activity in the colon, prostaglandin (PG) E2 promotes intestinal tumorigenesis. Expression of the PGE2 receptor EP4 is upregulated during colorectal carcinogenesis. Therefore, we investigated the role of elevated PGE2-EP4 receptor signalling in the protumorigenic activity of PGE2 by increasing EP4 receptor expression in HT-29 human colorectal cancer (CRC) cells (HT-29-EP4) by stable transfection. Elevated PGE2-induced EP4 receptor activity in HT-29 cells increased resistance to spontaneous apoptosis and promoted anchorage-independent growth, but had no effect on proliferation of HT-29-EP4 cells. EP4 receptor activation by PGE2 in HT-29-EP4 cells also led to development of fluid-filled cysts, which was associated with increased tight junction protein (occludin and zonula occludens-1) expression. Overexpression of the EP4 receptor in HT-29 cells led to basal EP4 receptor signalling in the absence of exogenous PGE2, which was explained by autocrine activity of endogenous, COX-2-derived PGE2 and constitutive, ligand-independent EP4 receptor activity. The predominant signalling pathway mediating antiapoptotic activity downstream of PGE2-EP4 receptor activation in HT-29-EP4 cells was elevation of cyclic adenosine monophosphate (cAMP) levels, which was associated with phosphorylation of cAMP-response element binding protein. EP4 receptor activation led to a small increase in phosphorylated extracellular signal-regulated kinase (ERK) 2 protein levels but inhibition of ERK phosphorylation did not abrogate the antiapoptotic activity of PGE2. However, PGE2-EP4 receptor signalling did not lead to trans-activation of the epidermal growth factor receptor in HT-29 cells. Inhibition of protumorigenic PGE2-EP4 receptor signalling represents a potential strategy for anti-CRC therapy that may avoid the toxicity associated with systemic COX inhibition.

Regulation of stromal cell cyclooxygenase-2 in the Apc Min/+ mouse model of intestinal tumorigenesis

Cyclooxygenase-2 (Cox-2) is expressed predominantly by stromal cells in intestinal adenomas from the Apc(Min/+) mouse model of familial adenomatous polyposis. We investigated the mechanistic basis of stromal cell Cox-2 expression in Apc(Min/+) mouse adenomas, as well as Cox-2 expression and activity in histologically normal (HN) Apc(Min/+) mouse intestine, in order to gain further insights into regulation of Cox-2 as a potential chemoprevention target. Upregulation of Cox-2 in intestinal tumours is not an intrinsic feature of Apc(Min/+) macrophages as bone marrow-derived Apc(Min/+) macrophages did not exhibit an abnormality in Cox-2 expression or activity. Intestinal permeability to lactulose or mannitol was similar in Apc(Min/+) mice and wild-type littermates, implying that macrophage activation by luminal antigen is unlikely to explain stromal cell Cox-2 induction. Moreover, stromal cells exhibited differential expression of Cox-2 and inducible nitric oxide synthase, suggesting 'alternative' (M2) rather than 'classical' (M1) macrophage activation. Flow cytometric sorting of isolated stromal mononuclear cells (SMNCs), on the basis of M-lysozyme and specific macrophage marker expression, demonstrated that macrophages, neutrophils and non-myelomonocytic cells all contributed to lamina propria prostaglandin (PG) E(2) synthesis. However, the majority of PGE(2) synthesis by macrophages was via a Cox-2-dependent pathway compared with predominant Cox-1-derived PGE(2) production by non-myelomonocytic cells. SMNCs from HN Apc(Min/+) intestinal mucosa exhibited similar levels of Cox-2 mRNA and protein, but produced more Cox-2-derived PGE(2) than wild-type cells at 70 days of age. There was an age-dependent decline in PGE(2) synthesis by Apc(Min/+) SMNCs, despite tumour progression. These data suggest that other Cox-2-independent factors also control PGE(2) levels during Apc(Min/+) mouse intestinal tumorigenesis. Regulation of macrophage Cox-2 expression and other steps in PGE(2) synthesis (e.g. PGE synthase) are valid targets for novel chemoprevention strategies that could minimize or avoid systemic COX-2 inhibition.

Effect of nonsteroidal anti-inflammatory drugs on beta-catenin protein levels and catenin-related transcription in human colorectal cancer cells

Elevated β-catenin levels in human colorectal cancer (CRC) cells lead to increased trans-activation of ‘protumorigenic’ β-catenin/T-cell factor (TCF) target genes such as cyclin D1. Therefore, possible targets for the anti-CRC activity of nonsteroidal anti-inflammatory drugs (NSAIDs) are β-catenin and catenin-related transcription (CRT). We tested the antiproliferative activity and the effects on levels of β-catenin and cyclin D1 protein, as well as CRT (measured using a synthetic β-catenin/TCF-reporter gene [TOPflash]), of a panel of NSAIDs (indomethacin, diclofenac, sulindac sulphide and sulphone, rofecoxib; range 10–600 μM) on SW480 human CRC cells in vitro. Following NSAID treatment, there was no consistent relationship between reduced cell proliferation, induction of apoptosis and changes in β-catenin protein levels or CRT. All the NSAIDs, except rofecoxib, decreased nuclear β-catenin content and cyclin D1 protein levels in parallel with their antiproliferative activity. However, cyclin D1 downregulation occurred prior to a decrease in total β-catenin protein levels and there was no correlation with changes in CRT, suggesting the existence of CRT-independent effects of NSAIDs on cyclin D1 expression. In summary, NSAIDs have differential effects on β-catenin protein and CRT, which are unlikely to fully explain their effects on cyclin D1 and their antiproliferative activity on human CRC cells in vitro.

Fulminant Crohn's colitis after allogeneic stem cell transplantation

We report a case of fulminant Crohn's colitis that occurred following non-myeloablative allogeneic stem cell transplantation for Hodgkin's lymphoma. Adoptive transfer of inflammatory bowel disease by haematopoietic cells is recognised in several animal models of inflammatory bowel disease and remission of Crohn's disease has been reported in patients who have received a bone marrow transplant. However, adoptive transfer of Crohn's disease susceptibility leading to phenotypic manifestation of the disease after transplantation has not been previously reported. Having ruled out an infective cause of a colitis in this case, we speculated that adoptive transfer of Crohn's disease may have occurred and performed a genetic analysis of known susceptibility loci for significant donor-recipient mismatches. The donor and recipient had several haplotype mismatches in HLA class III genes at the IBD3 locus. In addition, the donor (but not the recipient) had a polymorphism of the 5' UTR of NOD2/CARD15 that may be associated with Crohn's disease. This case highlights the question of whether adoptive transfer of Crohn's disease can occur between allogeneic stem cell transplant donor and recipient, in a similar fashion to that reported for other autoimmune diseases. This report should also stimulate debate regarding the need for stem cell transplant donor screening for inflammatory bowel disease.

Activity of the non-steroidal anti-inflammatory drug indomethacin against colorectal cancer

A substantial body of evidence from rodent colon carcinogenesis models, in vitro experiments with human colorectal cancer cells and limited clinical observations in humans suggest that the non-steroidal anti-inflammatory drug indomethacin has anti-colorectal cancer activity. However, although many mechanisms of the anti-neoplastic activity of indomethacin have been suggested, e.g., cyclooxygenase inhibition and peroxisome proliferator-activated receptor gamma activation, the precise relevance of the majority of in vitro pharmacological observations to the in vivo anti-neoplastic activity of indomethacin remains unclear. Herein, we review the existing literature describing the chemopreventative and chemotherapeutic efficacy of indomethacin against colorectal cancer, and draw together the disparate literature describing potential mechanisms of action of indomethacin in human colorectal cancer cells in vitro. Although indomethacin itself has significant adverse effects, including serious upper gastrointestinal toxicity, the development of novel derivatives that may have an improved safety profile means that further investigation of the anti-colorectal cancer activity of indomethacin is warranted.

Activation of peroxisome proliferator-activated receptor gamma does not explain the antiproliferative activity of the nonsteroidal anti-inflammatory drug indomethacin on human colorectal cancer cells

The mechanism of the anticolorectal cancer activity of the nonsteroidal anti-inflammatory drug indomethacin is poorly understood. Indomethacin inhibits both cyclooxygenase (COX) isoforms, but it may also act via COX-independent targets. Indomethacin can bind and activate the transcription factor peroxisome proliferator-activated receptor (PPAR) gamma. Moreover, natural and synthetic PPARgamma ligands can induce growth arrest and apoptosis of human colorectal cancer cells in vitro. Therefore, we tested the hypothesis that the antiproliferative activity of indomethacin on human colorectal cancer cells in vitro is explained by a PPARgamma-dependent mechanism of action. Human colorectal cancer cell lines SW480 and HCT116 both expressed functional PPARgamma. Indomethacin directly activated PPARgamma in both cell lines (HCT116 > SW480). A dominant-negative PPARgamma strategy was used to demonstrate that endogenous PPARgamma represses proliferation of HCT116 cells (compatible with tumor suppressor activity) but that the presence of functional PPARgamma is not necessary for the antiproliferative activity (or reduction in cyclin D1 protein) associated with indomethacin in vitro. In summary, indomethacin (>100 microM) directly activates PPARgamma in human colorectal cancer cells. However, PPARgamma activation does not underlie the antineoplastic activity of indomethacin on human colorectal cancer cells in vitro.

Percutaneous endoscopic gastrostomy (PEG): change in practice since 1988

BACKGROUND AND AIMS

We previously reported a 30-day mortality following percutaneous endoscopic gastrostomy (PEG) of 8% (1988-92). Concerns over increasing mortality rates prompted us to survey current practice compared with 1988-92: assess case mix, outcome, risk factors for early death, and review practice guidelines.

METHODS

78 consecutive adults were referred for PEG over 7 months. Baseline characteristics, including age and functional status (Barthel Index), and outcome at 30 and 180 days were prospectively evaluated.

RESULTS

74 patients. Median age 69 years; male 55%. Major underlying diagnoses: cerebrovascular disease 42%, head and neck tumours 19%, motor neurone disease 4% (33%, 16% and 27% in 1988-92). Mortality rates at 30, 90 and 180 days were 19%, 35% and 42% respectively (8%, 20% and 37% in 1988-92). Univariate analysis showed that age >75 years, Barthel Index <1 and Glasgow Coma Scale < or =10 were significant risk factors for death at 30 days: odds ratios (95% confidence intervals) 3.9 (1.1-13), 5.9 (1.4-25) and 4.4 (1.2-15) respectively.

CONCLUSIONS

30-day mortality was increased from 8% to 19% between 1988-92 and 1998-99 reflecting a change in referral patterns: more elderly with cerebrovascular disease and fewer with motor neurone disease. Age and functional status should be considered when advising on PEG feeding.

Variable use of endoscopic haemostasis in the management of bleeding peptic ulcers

BACKGROUND

Randomised controlled trials (RCTs) have shown that endoscopic haemostasis is beneficial for patients with a bleeding peptic ulcer. The relevance of such data to management outside of RCTs is unclear. Therefore we examined management of patients with a bleeding peptic ulcer in a UK teaching hospital.

METHODS

All patients who underwent upper gastrointestinal (UGI) endoscopy for bleeding peptic ulcer between 1997 and 1999 were identified from an endoscopy database and the clinical records reviewed retrospectively.

RESULTS

A total of 872 patients underwent UGI endoscopy for presumed acute UGI haemorrhage; 179 (21%) had an endoscopic diagnosis of bleeding peptic ulcer. Seventy nine patients had a peptic ulcer with stigmata of recent haemorrhage (SRH) but only 61 (77%) of these patients received endoscopic haemostasis (77% adrenaline, 23% combination therapy). Re-bleeding occurred in 24 patients with SRH in whom transfusion requirement was the sole predictor of re-bleeding. The re-bleeding rate among patients who received adrenaline was 25% (n=12), compared with 57% (n=8) in the combination group and 31% (n=4) in those who did not receive endoscopic haemostasis. Patients who received combination endoscopic haemostasis had an increased incidence of active bleeding (p=0.007) and an increased transfusion requirement (p=0.002). Eleven of 20 patients who re-bled had repeat endoscopic haemostasis, with 45% eventually requiring surgery.

CONCLUSIONS

Results of endoscopic management of bleeding peptic ulcers in the unit studied differ markedly from those published by specialised centres. The data reported here suggest that increased standardisation of endoscopic haemostasis is required, especially in units with provision for emergency "out-of-hours" endoscopy, performed by several individuals of different grades.

Lack of inducible nitric oxide synthase promotes intestinal tumorigenesis in the Apc(Min/+) mouse

BACKGROUND & AIMS

The role of the inducible isoform of nitric oxide synthase (Nos2 or iNOS) in intestinal tumorigenesis is unclear. Conflicting data also exist regarding the ability of Nos2 to modulate expression and/or activity of cyclooxygenase 2 (Cox-2), which promotes intestinal tumorigenesis. Therefore, we determined the effect of a null Nos2 genotype on intestinal tumorigenesis and Cox-2 expression/activity in the Apc(Min/+) mouse model of familial adenomatous polyposis.

METHODS

Apc(Min/+)Nos2(-/-) mice were generated by successive crosses between C57BL/6-Apc(Min/+) and C57BL/6-Nos2(tm1Lau) mice. Adenoma characteristics of age-matched Apc(Min/+)Nos2(+/+) and Apc(Min/+)Nos2(-/-) mice were compared. The level and cellular localization of Nos2 messenger RNA (mRNA) expression in Apc(Min/+)Nos2(+/+) mouse intestine was determined. Cox-2 expression and activity were measured in both intestinal tissue and bone marrow-derived macrophages in vitro.

RESULTS

Apc(Min/+)Nos2(-/-) mice developed significantly more intestinal adenomas than Apc(Min/+)Nos2(+/+) littermates. Epithelial cell Nos2 mRNA expression was decreased in adenomas compared with histologically normal Apc(Min/+)Nos2(+/+) intestine. There was no significant difference in Cox-2 expression or activity in either intestine or bone marrow-derived macrophages from Apc(Min/+)Nos2(+/+) and Apc(Min/+)Nos2(-/-) animals.

CONCLUSIONS

Nos2 plays an antineoplastic role in the Apc(Min/+) mouse model of familial adenomatous polyposis. Nos2 does not modulate Cox-2 expression or activity in the Apc(Min/+) mouse.

Cyclooxygenase-2 expression in colorectal cancer liver metastases

Cyclooxygenase-2 (COX-2) is up-regulated in 85-90% of primary human colorectal cancers and is a putative target for the chemopreventative activity of non-steroidal anti-inflammatory drugs. However, COX-2 expression by human colorectal cancer liver metastases has been poorly characterized. We studied a consecutive series of 38 patients who underwent liver resection for metastatic disease, for whom long-term (up to 57 months), prospective follow-up data were available. Semi-quantitative immunohistochemistry for COX-2 was performed on 54 metastases from 35 patients, for whom adequate histological material was available. Diffuse cytoplasmic staining for COX-2 protein was detected in cancer cells in 100% of metastases (COX-2 score 1, n = 25; score 2, n = 29). There was no relationship between metastasis size or differentiation grade and the level of COX-2 protein expression. There was no difference in colorectal cancer-free or overall survival between patients with high (score 2) and low (score 1) COX-2 scores (Kaplan-Meier survival analysis and log rank test, both P = 0.97). Multivariate Cox regression analysis identified age, incomplete resection and presence of extra-hepatic disease as independent predictors of disease-free and overall survival following surgery. COX-2 protein was also localized to a subset of stromal fibroblasts and mononuclear cells within metastases as well as hepatocytes from resection specimens. COX-2 protein was expressed by cancer cells in all human colorectal cancer liver metastases which were studied. Investigation of the effect of selective COX-2 inhibition on metastasis growth and metastasis cancer cell proliferation/apoptosis in vivo are warranted.

The effect of non-steroidal anti-inflammatory drugs on human colorectal cancer cells: evidence of different mechanisms of action

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit proliferation and induce apoptosis in human colorectal cancer cells in vitro. It remains unclear whether individual NSAIDs act by cyclooxygenase-2 (COX-2) inhibition and how NSAIDs exert their anti-proliferative effects. We investigated the effects of NS-398 (a selective COX-2 inhibitor), indomethacin (a non-selective COX inhibitor) and aspirin on four human colorectal cancer cell lines (HT29.Fu, HCA-7, SW480 and HCT116). NS-398 completely inhibited proliferation, induced G1 arrest and promoted apoptosis in COX-2-expressing cells (HT29.Fu and HCA-7). However, indomethacin had similar effects on all cells, regardless of COX-2 expression. NS-398 also had anti-proliferative activity on COX-2-negative cell lines (SW480 and HCT116). Aspirin inhibited proliferation of all cell lines but did not induce apoptosis. Indomethacin decreased beta-catenin protein expression in all cells (unlike NS-398 or aspirin). NSAIDs act on human colorectal cancer cells via different mechanisms. Decreased beta-catenin protein expression may mediate the anti-proliferative effects of indomethacin.

Localization of cyclooxygenase-2 in human sporadic colorectal adenomas

A putative target for the anti-colorectal cancer action of nonsteroidal anti-inflammatory drugs is the inducible isoform of cyclooxygenase (COX), COX-2. COX-2 is expressed within intestinal adenomas in murine polyposis models, but expression has been poorly characterized in human colorectal neoplasms. Therefore, we investigated the localization of the COX-2 protein in human sporadic colorectal adenomas. Immunohistochemistry for COX-2 and CD68 (a tissue macrophage marker) was performed on formalin-fixed, paraffin-embedded (n = 52) and frozen, acetone-fixed (n = 6) sections of human sporadic colorectal adenomas. Forty of 52 (77%) formalin-fixed adenomas expressed immunoreactive COX-2. COX-2 was localized to superficial interstitial macrophages in 39 cases (75%) and to deep interstitial macrophages in 9 cases (17%). COX-2 staining of dysplastic epithelial cells was observed in 15 cases (29%). A logistic regression analysis identified the adenoma site (P = 0.012) and histological type (P = 0.001) as independent predictors of superficial macrophage COX-2 expression. There was no relationship between the number of macrophages within an adenoma and macrophage COX-2 expression. These results indicate that COX-2 is expressed predominantly by interstitial macrophages within human sporadic colorectal adenomas. If COX-2 does indeed play a role in the early stages of colorectal carcinogenesis in man, these data suggest COX-2-mediated paracrine signaling between the macrophages and epithelial cells within adenomas.

Non-steroidal anti-inflammatory drugs inhibit Helicobacter pylori-induced human neutrophil reactive oxygen metabolite production in vitro

BACKGROUND

Helicobacter pylori infection is associated with increased production of gastric mucosal reactive oxygen metabolites which have been implicated in mucosal damage and carcinogenesis. In vitro, neutrophils produce reactive oxygen metabolites following activation by H. pylori. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit neutrophil activation by several factors, e.g. N-formyl-methionyl-leucyl-phenyalanine (f-MLP).

AIM

To examine the effect of NSAIDs on H. pylori-induced reactive oxygen metabolite production by human peripheral blood neutrophils.

METHODS

Neutrophils were stimulated by H. pylori (NCTC 11637) water extract or f-MLP in the presence or absence of NSAIDs. Reactive oxygen metabolite activity was measured by luminol-enhanced chemiluminescence.

RESULTS

H. pylori water extract stimulated a sevenfold increase in chemiluminescence which was inhibited dose-dependently by diclofenac. All six NSAIDs studied (at 10-4 M) significantly inhibited H. pylori-and f-MLP-stimulated neutrophil reactive oxygen metabolite production. Meclofenamic acid and diclofenac had the greatest inhibitory effects on both H. pylori and f-MLP-stimulated neutrophil reactive oxygen metabolite production. The inhibitory effects of other NSAIDs varied with the activation stimulus. NSAIDs did not quench reactive oxygen metabolites generated in a cell-free xanthine:xanthine oxidase assay.

CONCLUSION

Several NSAIDs attenuate H. pylori-induced neutrophil reactive oxygen metabolites production in vitro. This may be relevant to a potential chemopreventative role in gastric cancer and to a possible lack of synergy between H. pylori and NSAID use regarding peptic ulceration.

Expression of cyclooxygenase 1 and 2 by human gastric endothelial cells

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) and cause gastric ulceration. NSAIDs also impair granulation tissue angiogenesis and healing of established gastric ulcers in humans. The mechanism whereby NSAIDs inhibit granulation tissue angiogenesis is unknown but may involve inhibition of either or both COX isoforms (COX-1 and COX-2).

AIMS

To investigate COX expression by human gastric endothelial (HuGE) cells during angiogenesis in vitro.

METHODS

COX-1 and COX-2 expression by HuGE cells was investigated by western blot analysis, indirect immunofluorescence, reverse transcriptase polymerase chain reaction, and measurement of prostaglandin E(2) synthesis. Plating onto basement membrane matrix and stimulation by phorbol ester were used as in vitro models of angiogenesis.

RESULTS

Under normal culture conditions (30% serum), HuGE cells expressed COX-1 and low levels of COX-2. COX-2 expression was induced in HuGE cells in both angiogenesis models. Prostaglandin E(2) production and tubular structure formation by HuGE cells on basement membrane matrix was significantly inhibited by a selective COX-2 inhibitor (NS-398).

CONCLUSION

Angiogenesis by HuGE cells in vitro was associated with induction of functional COX-2 expression. A selective COX-2 inhibitor significantly decreased HuGE cell angiogenesis on basement membrane matrix. Extrapolation of these data to human gastric ulcer angiogenesis in vivo suggests that selective COX-2 inhibitors could delay gastric ulcer healing to the same extent as traditional NSAIDs which are non-selective COX inhibitors.

Cyclooxygenase 2 is up-regulated and localized to macrophages in the intestine of Min mice

Expression of cyclooxygenase 2 (COX-2) is believed to play an important role in adenoma formation in murine polyposis models, and inhibition of COX-2 activity may, at least, partly explain the chemopreventative activity of non-steroidal anti-inflammatory drugs against colorectal cancer in humans. However, the mechanism by which COX-2 acts in intestinal tumorigenesis remains unresolved because of conflicting data on the cellular localization of COX-2 in intestinal mucosa. Using immunohistochemistry with specific COX-2 antiserum, we have shown that COX-2 protein is localized to interstitial cells at the base of and within adenomas of the small and large intestine of multiple intestinal neoplasia (Min) mice. No COX-2 staining was observed in dysplastic epithelial cells within adenomas or in histologically normal epithelium. Moreover, COX-2 staining was observed in lamina propria cells of histologically normal intestine of Min mice. No staining was demonstrated in wild-type littermates. The rat monoclonal antibody F4/80 was used to show that COX-2-positive cells represented a subset of the macrophage population present in the intestine of Min mice. Localization of COX-2 to macrophages implies a paracrine effect of COX-2 function on epithelial cells in adenomas and also on histologically normal epithelium. Up-regulation of COX-2 expression in lamina propria macrophages may precede loss of the second functional Apc allele in epithelial cells before adenoma formation in the Min mouse model of intestinal tumorigenesis.

Expression of basic fibroblast growth factor in intact and ulcerated human gastric mucosa

BACKGROUND

Basic fibroblast growth factor (bFGF) promotes angiogenesis and healing of gastric ulcers in rats, and bFGF expression is up regulated in such ulcers. However, little is known about expression of bFGF in human gastric mucosa.

AIMS

To investigate bFGF expression in intact human gastric mucosa and gastric ulcers and to determine whether low bFGF content or altered binding by mucosa is associated with ulceration.

SUBJECTS

Endoscopy outpatients, gastrectomy patients, and organ donors.

METHODS

bFGF was isolated by heparin affinity chromatography and characterised by western blotting and endothelial cell bioassay. bFGF was measured by immunoassay and its distribution defined by immunohistochemistry and in situ hybridisation. Binding of bFGF by heparan sulphate proteoglycans was investigated by sodium chloride and heparin extraction.

RESULTS

Bioactive bFGF (19 kDa) was detected in normal mucosa but bFGF mRNA was not found. bFGF expression was up regulated in granulation tissue endothelial cells, mononuclear cells, and epithelial cells at the ulcer rim. Gastric ulcer patients had constitutively low bFGF concentrations in intact antral mucosa which were not explained by changes in binding to heparan sulphate proteoglycans.

CONCLUSIONS

bFGF expression is up regulated in human gastric ulcers. Low intact mucosal bFGF content is associated with gastric ulceration.

Phase III interlaboratory study of FETAX, Part 2: interlaboratory validation of an exogenous metabolic activation system for frog embryo teratogenesis assay--Xenopus (FETAX)

Interlaboratory validation of an exogenous metabolic activation system (MAS) developed for the alternative, short-term developmental toxicity bioassay, Frog Embryo Teratogenesis Assay-Xenopus (FETAX) was performed with cyclophosphamide and caffeine. Seven study groups within six separate laboratories participated in the study in which three definitive concentration-response experiments were performed with and without the MAS in a side-by-side format for each chemical. Since both chemicals had been previously tested in FETAX, the test concentrations were provided to each laboratory prior to testing. Interlaboratory coefficient of variation (CV) values for unactivated cyclophosphamide (no MAS) were 15%, 15%, 29%, and 25% for the 96-hr LC50, 96-hr EC50 (malformation), Minimum Concentration to Inhibit Growth (MCIG), and Teratogenic Index (TI) values, respectively. Addition of the MAS increased the CV values of each endpoint at least 3.9-fold. Interlaboratory CV values for unactivated caffeine were 31%, 18%, 31%, and 46% for the 96-hr LC50, 96-hr EC50 (malformation), MCIG, and TI values, respectively. Addition of the MAS decreased the CV values of each respective endpoint by at least 1.6-fold. Results indicated that bioactivated toxicants may be prone to greater variability in response amongst laboratories than compounds, which are detoxified. Even though more variability was noted with activated cyclophosphamide, results were within interlaboratory variation expected for other aquatic-based bioassays. Thus, results from these studies warrant the continued use and further refinement of FETAX for alternative developmental toxicity assessment.

Evaluation of the developmental toxicities of coumarin, 4-hydroxycoumarin, and 7-hydroxycoumarin using FETAX

The developmental toxicities of coumarin and hydroxycoumarin metabolites were evaluated using FETAX. Young X. laevis embryos were exposed to coumarin, 4-hydroxycoumarin, and 7-hydroxycoumarin in each of two separate concentration-response experiments with and without an exogenous metabolic activation system (MAS) and/or inhibited MAS. The MAS was treated with carbon monoxide (CO), cimetidine (CIM), or ellipticine (ELL) to selectively modulate cytochrome P-450 activity. The MAS was also treated with cyclohexene oxide (CHO) to selectively modulate epoxide hydrolase activity. Without the MAS or inhibited MAS, coumarin and 7-hydroxycoumarin were nearly equitoxic, whereas 4-hydroxycoumarin was nearly 2-fold less developmentally toxic than coumarin on an equimolar basis. Addition of the MAS and CIM-MAS increased the developmental toxicities of coumarin and, particularly, 4-hydroxycoumarin. Addition of the CHO-MAS greatly increased the developmental toxicity of coumarin and, especially, 4-hydroxycoumarin. Addition of the ELL- or CO-inhibited MAS did not increase the developmental toxicity of coumarin. However, addition of the intact MAS did not alter the developmental toxicity of 7-hydroxycoumarin. Results from these studies suggested that P-450; specifically ELL-inhibited P-450 (arylhydrocarbon hydroxylase) may have been responsible for increasing the developmental toxicity of coumarin. Furthermore, the increased toxicity of coumarin or 4-hydroxycoumarin following co-incubation with CHO-treated microsomes indicated that highly toxic epoxide intermediates may be produced from oxidative P-450 metabolism and that epoxide hydrolase may play a role in detoxification of the reactive intermediates.

Healing with basic fibroblast growth factor is associated with reduced indomethacin induced relapse in a human model of gastric ulceration

BACKGROUND

Acid stable basic fibroblast growth factor (bFGF) promotes angiogenesis and healing of gastric ulcers in rats and reduces subsequent non-steroidal anti-inflammatory drug (NSAID) induced relapse.

AIMS

To test in a double blind, placebo controlled, three way crossover study whether bFGF promotes healing and reduces subsequent relapse in a human model of gastric ulceration.

SUBJECTS

Twelve healthy volunteers.

METHODS

Subjects took aspirin 900 mg twice daily (days 1-3) with bFGF 0.1 mg twice daily or cimetidine 400 mg twice daily or placebo (days 1-14) and then indomethacin 50 mg thrice daily (days 15-21). Endoscopy was performed on days 1, 4, 8, 15, and 22 during each treatment period. Eight antral biopsy specimens were taken on day 1 and the number of unhealed biopsy induced mini-ulcers and NSAID induced erosions counted during subsequent endoscopies.

RESULTS

Basic FGF and cimetidine were protective against aspirin and indomethacin induced duodenal (but not gastric) injury compared with placebo. There was significant relapse of biopsy induced mini-ulcers after indomethacin only in the placebo group (0 (0-0) before v 1 (0-4.5) after; p > 0.05). TGP-580 was detected in serum of one volunteer.

CONCLUSIONS

Healing with bFGF (and cimetidine) was associated with reduced NSAID induced ulcer relapse in this model of gastric ulceration.

Isolation and culture of human gastric endothelial cells

BACKGROUND & AIMS

Angiogenesis plays an important role in gastric ulcer healing. Considerable heterogeneity exists between endothelial cells from different blood vessels in vitro. Hitherto, it has not been possible to study gastric angiogenesis using relevant endothelial cells. The aim of this study was to isolate and culture human gastric endothelial (HuGE) cells to allow investigation of gastric ulcer angiogenesis.

METHODS

Gastric mucosa underwent mechanical and enzymatic disruption. Microvessel fragments and endothelial cells were selected using superparamagnetic beads (Dynabeads; Dynal, Wirral, England) coated with a murine monoclonal anti-human platelet-endothelial cell adhesion molecule 1 antibody. Contaminating nonendothelial cells were removed by mechanical weeding and further Dynabead separation of endothelial cells.

RESULTS

HuGE cells have been cultured up to passage 19. HuGE cells formed contact-inhibited monolayers on gelatin coated surfaces and tube-like structures on basement membrane matrices. Indirect immunofluorescence studies confirmed the endothelial nature of these cells. Basic and acidic fibroblast growth factors and vascular endothelial growth factor promoted proliferation (but not epidermal growth factor). HuGE cells synthesized less prostaglandin I2 and E2 compared with human umbilical vein endothelial cells.

CONCLUSIONS

Pure cultures of HuGE cells can be obtained. Physiologically important differences from large vessel endothelial cells require further investigation.

Evaluation of the developmental toxicity of theophylline, dimethyluric acid, and methylxanthine metabolites using Xenopus

The developmental toxicities of theophylline and theophylline metabolites were evaluated using FETAX (Frog Embryo Teratogenesis Assay - Xenopus). Young X. laevis embryos were exposed to theophylline, 1-methylxanthine, 3-methylxanthine, or 1, 3-dimethyluric acid in each of two separate concentration-response experiments with and without an exogenous metabolic activation system (MAS) and/or inhibited MAS. The MAS was treated with carbon monoxide (CO), cimetidine (CIM), or ellipticine (ELL) to selectively modulate cytochrome P-450 activity. Addition of the MAS and CIM-MAS reduced the developmental toxicity of theophylline. Addition of the ELL- or CO-inhibited MAS did not reduce the developmental toxicity of theophylline. Addition of the intact MAS did not alter the developmental toxicity of 1-methyl- or 3-methylxanthine which were slightly more developmentally toxic on an equimolar basis than theophylline itself. 1, 3-dimethyluric acid was not developmentally toxic at maximum soluble concentrations in 1% (V/V) DMSO. Results from these studies suggested that P-450, specifically ELL-inhibited P-450 (aryl hydrocarbon hydroxylase) may have been responsible for detoxification of theophylline and that 1, 3 dimethyluric acid represented the primary detoxification metabolite of theophylline.

Basic fibroblast growth factor treatment for non-steroidal anti-inflammatory drug associated gastric ulceration

An open, pilot study tested the safety and efficacy of an acid stable form of the angiogenic protein basic fibroblast growth factor (bFGF) for healing of non-steroidal anti-inflammatory drug (NSAID) associated gastric ulcers in five patients with nine gastric ulcers that were resistant to conventional treatment (4) or had relapsed (5). Oral bFGF treatment for four weeks was safe and well tolerated. There was no evidence of systemic absorption. After four weeks, four ulcers had healed and there was a 89 (3)% mean (SEM) reduction in the area of the others. A controlled, comparative trial of this novel growth factor treatment is warranted.

Audit of outcome of long-term enteral nutrition by percutaneous endoscopic gastrostomy

Percutaneous endoscopic gastrostomy (PEG) is the preferred method for administration of long-term enteral tube feeding. However, most published studies describe only short-term follow-up in any detail. We report the long-term outcome and complication rate after PEG insertion in 49 patients (mean [SE] age 64 [2] years) whose mean length of PEG feeding was 175 days (range 30-560). Data were collected prospectively. PEG insertion was technically successful in all cases, with a procedure-related mortality of 2%. Early (< 30 days) mortality and morbidity were 8% and 22%, respectively. Of 45 patients surviving for more than 30 days, 76% were able to return home and 6 patients were eventually able to revert to oral feeding. There were 27 late complications: 2 site infections, 17 mechanical problems, and 8 episodes of gastrointestinal dysfunction. 51% of patients had no problems at all and 22% had 2 or more complications. 47% of complications required a hospital visit for resolution. Long-term enteral feeding by PEG was safe, effective, and had a low complication rate. Our patients were managed by a specialist nutrition team, a policy that may reduce the complication rate and hospital visits for patients being fed at home, and allow early discharge of dysphagic patients, thereby reducing costs.