Gut microbiota composition is associated with SARS-CoV-2 vaccine immunogenicity and adverse events

OBJECTIVE

The gut microbiota plays a key role in modulating host immune response. We conducted a prospective, observational study to examine gut microbiota composition in association with immune responses and adverse events in adults who have received the inactivated vaccine (CoronaVac; Sinovac) or the mRNA vaccine (BNT162b2; BioNTech; Comirnaty).

DESIGN

We performed shotgun metagenomic sequencing in stool samples of 138 COVID-19 vaccinees (37 CoronaVac and 101 BNT162b2 vaccinees) collected at baseline and 1 month after second dose of vaccination. Immune markers were measured by SARS-CoV-2 surrogate virus neutralisation test and spike receptor-binding domain IgG ELISA.

RESULTS

We found a significantly lower immune response in recipients of CoronaVac than BNT162b2 vaccines (p<0.05). Bifidobacterium adolescentis was persistently higher in subjects with high neutralising antibodies to CoronaVac vaccine (p=0.023) and their baseline gut microbiome was enriched in pathways related to carbohydrate metabolism (linear discriminant analysis (LDA) scores >2 and p<0.05). Neutralising antibodies in BNT162b2 vaccinees showed a positive correlation with the total abundance of bacteria with flagella and fimbriae including Roseburia faecis (p=0.028). The abundance of Prevotella copri and two Megamonas species were enriched in individuals with fewer adverse events following either of the vaccines indicating that these bacteria may play an anti-inflammatory role in host immune response (LDA scores>3 and p<0.05).

CONCLUSION

Our study has identified specific gut microbiota markers in association with improved immune response and reduced adverse events following COVID-19 vaccines. Microbiota-targeted interventions have the potential to complement effectiveness of COVID-19 vaccines.

Association of Adherent-invasive Escherichia coli with severe Gut Mucosal dysbiosis in Hong Kong Chinese population with Crohn's disease

Adherent invasive Escherichia Coli (AIEC) has been implicated in the pathogenesis of Crohn's disease (CD) in Western populations. Whether the presence of AIEC is also seen in CD populations of different genetic susceptibility and has negative impact on host microbiota ecology and therapeutics are unclear. AIEC presence was assessed in ileal tissues of 60 Hong Kong Chinese patients with CD and 56 healthy subjects. Mucosa microbiota was analyzed by 16s rRNA sequencing. Impact of AIEC on the gut microbiota was determined in a mouse model. AIEC was significantly more prevalent in ileal tissues of patients with CD than controls (30% vs 7.1%). Presence of AIEC in ileal tissues was associated with more severe mucosa microbiota dysbiosis in CD with decreased diversity and lower abundance of Firmicutes including butyrate producing Roseburia and probiotic Bacillus. A random forest model predicted the presence of AIEC with area under the curve of 0.89. AIEC exacerbated dysbiosis in dextran sodium sulfate (DSS)-induced colitis mice and led to resistance to restoration of normal gut microbiota by fecal microbiota transplantation (FMT). Proportion of donor-derived bacteria in AIEC-colonized mice was significantly lower than that in uninfected mice. AIEC was prevalent and associated with severe mucosa microbiota dysbiosis in CD in Hong Kong Chinese population. The presence of AIEC impeded restoration of normal gut microbiota. AIEC may serve as a keystone bacterium in CD and impact the efficacy of FMT.

Risks of post-colonoscopic polypectomy bleeding and thromboembolism with warfarin and direct oral anticoagulants: a population-based analysis

BACKGROUND

There were limited data on the risk of post-polypectomy bleeding (PPB) in patients on direct oral anticoagulants (DOAC). We aimed to evaluate the PPB and thromboembolic risks among DOAC and warfarin users in a population-based cohort.

METHODS

We performed a territory-wide retrospective cohort study involving patients in Hong Kong from 2012 to 2020. Patients who received an oral anticoagulant and had undergone colonoscopy with polypectomy were identified. Propensity-score models with inverse probability of treatment weighting were developed for the warfarin-DOAC and between-DOAC comparisons. The primary outcome was clinically significant delayed PPB, defined as repeat colonoscopy requiring haemostasis within 30 days. The secondary outcomes were 30-day blood transfusion requirement and new thromboembolic event.

RESULTS

Apixaban was associated with lower PPB risk than warfarin (adjusted HR (aHR) 0.39, 95% CI 0.24 to 0.63, p<0.001). Dabigatran (aHR 2.23, 95% CI 1.04 to 4.77, adjusted p (ap)=0.035) and rivaroxaban (aHR 2.72, 95% CI 1.35 to 5.48, ap=0.002) were associated with higher PPB risk than apixaban. In subgroup analysis, apixaban was associated with lower PPB risk in patients aged ≥70 years and patients with right-sided colonic polyps.For thromboembolic events, apixaban was associated with lower risk than warfarin (aHR 0.22, 95% CI 0.11 to 0.45, p<0.001). Dabigatran (aHR 2.60, 95% CI 1.06 to 6.41, ap=0.033) and rivaroxaban (aHR 2.96, 95% CI 1.19 to 7.37, ap =0.013) were associated with higher thromboembolic risk than apixaban.

CONCLUSIONS

Apixaban was associated with a significantly lower risk of PPB and thromboembolism than warfarin, dabigatran and rivaroxaban, particularly in older patients with right-sided polyps.

P6542Early Prolonged Ambulatory Cardiac monitoring in Stroke (EPACS): an open-label randomised controlled trial and economic evaluation

Background

Cardioembolism in paroxysmal atrial fibrillation (PAF) is a preventable cause of transient ischaemic attack (TIA) or ischaemic stroke, however, due its transient nature, a short-duration Holter monitor may miss a significant proportion of events.

Methods

We conducted an open-label randomised controlled trial of cardiac monitoring after a TIA or ischaemic stroke comparing a 14-day ECG monitoring patch with short-duration Holter monitoring for the detection of PAF. The primary outcome was the detection of one or more episodes of ECG-documented PAF lasting at least 30 seconds within 90 days in each of the study arms.

A budget impact analysis from the healthcare perspective was performed to assess the theoretical economic implications of the patch-based service versus Holter monitoring. Based on the AF detection rates found in this study, Hospital Episode Statistics data for the incidence of stroke and TIA (October 2016-September 2017) and National Health Service reference costs, the cost-effectiveness of the patch-based service versus Holter monitoring was calculated. The Sentinel Stroke National Audit Programme estimate of £13,452 was used as the mean year one direct medical cost of a stroke.

Results

From February 2016 through February 2017, 43 (76.8%) of the 56 patients assigned to the patch-based monitoring group and 47 (78.3%) of the 60 patients assigned to the short-duration Holter monitoring group had successful monitor placement with 90 days of follow-up (Figure 1). Of the 26 protocol failures between the two groups, 23 (88.5%) were due to patient refusal for outpatient short-duration Holter monitor placement, whilst only 1 (3.8%) was due to unsuccessful patch placement. The rate of detection of PAF at 90 days was 16.3% in the patch-based monitoring group (7 patients) compared to 2.1% in the short-duration Holter monitoring group (1 patient), with an odds ratio of 8.9 (95% CI 1.1–76.0; P=0.026).

Implementation of the patch-based service at our hospital would result in 10.8 more strokes avoided per year compared to current practice with short-duration Holter monitoring. This would equate to a yearly saving in direct medical costs of £57,481, increasing to £106,342 over 5 years. When social care costs are included, incremental savings of £154,716 can be achieved in the first year and £410,449 at 5 years. In addition, an analysis of the potential reduction in outpatient follow-up appointment costs resulted in a further saving of £56,149, giving a total potential saving of £113,630 over the first year with the use of the patch-based service compared to short-duration Holter monitoring, increasing to £162,491 over 5 years.

Figure 1. Study participant flowchart

Conclusions

Early, prolonged, patch-based monitoring after an index stroke or TIA is superior to short-duration Holter monitoring in the detection of PAF and likely cost-effective for preventing recurrent strokes.

Acknowledgement/Funding

Bristol-Myers Squibb-Pfizer alliance (Grant Number CV185-475)

Reduced lysosomal clearance of autophagosomes promotes survival and colonization of Helicobacter pylori

Evasion of autophagy is key for intracellular survival of bacteria in host cells, but its involvement in persistent infection by Helicobacter pylori, a bacterium identified to invade gastric epithelial cells, remains obscure. The aim of this study was to functionally characterize the role of autophagy in H. pylori infection. Autophagy was assayed in H. pylori-infected human gastric epithelium and the functional role of autophagy was determined via genetic or pharmacological ablation of autophagy in mouse and cell line models of H. pylori infection. Here, we showed that H. pylori inhibited lysosomal function and thereby promoted the accumulation of autophagosomes in gastric epithelial cells. Importantly, inhibiting autophagosome formation by pharmacological inhibitors or genetic ablation of BECN1 or ATG5 reduced H. pylori intracellular survival, whereas inhibition of lysosomal functions exerted an opposite effect. Further experiments demonstrated that H. pylori inhibited lysosomal acidification and the retrograde trafficking of mannose-6-phosphate receptors, both of which are known to positively regulate lysosomal function. We conclude that H. pylori subverts autophagy into a pro-survival mechanism through inhibition of lysosomal clearance of autophagosomes. Disruption of autophagosome formation offers a novel strategy to reduce H. pylori colonization in human stomachs. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Epigenetic inactivation of the CpG demethylase TET1 as a DNA methylation feedback loop in human cancers

Promoter CpG methylation is a fundamental regulatory process of gene expression. TET proteins are active CpG demethylases converting 5-methylcytosine to 5-hydroxymethylcytosine, with loss of 5 hmC as an epigenetic hallmark of cancers, indicating critical roles of TET proteins in epigenetic tumorigenesis. Through analysis of tumor methylomes, we discovered TET1 as a methylated target, and further confirmed its frequent downregulation/methylation in cell lines and primary tumors of multiple carcinomas and lymphomas, including nasopharyngeal, esophageal, gastric, colorectal, renal, breast and cervical carcinomas, as well as non-Hodgkin, Hodgkin and nasal natural killer/T-cell lymphomas, although all three TET family genes are ubiquitously expressed in normal tissues. Ectopic expression of TET1 catalytic domain suppressed colony formation and induced apoptosis of tumor cells of multiple tissue types, supporting its role as a broad bona fide tumor suppressor. Furthermore, TET1 catalytic domain possessed demethylase activity in cancer cells, being able to inhibit the CpG methylation of tumor suppressor gene (TSG) promoters and reactivate their expression, such as SLIT2, ZNF382 and HOXA9. As only infrequent mutations of TET1 have been reported, compared to TET2, epigenetic silencing therefore appears to be the dominant mechanism for TET1 inactivation in cancers, which also forms a feedback loop of CpG methylation during tumorigenesis.

Characterization of the nasopharyngeal carcinoma methylome identifies aberrant disruption of key signaling pathways and methylated tumor suppressor genes

AIMS

Nasopharyngeal carcinoma (NPC) is a common tumor consistently associated with Epstein-Barr virus infection and prevalent in South China, including Hong Kong, and southeast Asia. Current genomic sequencing studies found only rare mutations in NPC, indicating its critical epigenetic etiology, while no epigenome exists for NPC as yet.

MATERIALS & METHODS

We profiled the methylomes of NPC cell lines and primary tumors, together with normal nasopharyngeal epithelial cells, using methylated DNA immunoprecipitation (MeDIP).

RESULTS

We observed extensive, genome-wide methylation of cellular genes. Epigenetic disruption of Wnt, MAPK, TGF-β and Hedgehog signaling pathways was detected. Methylation of Wnt signaling regulators (SFRP1, 2, 4 and 5, DACT2, DKK2 and DKK3) was frequently detected in tumor and nasal swab samples from NPC patients. Functional studies showed that these genes are bona fide tumor-suppressor genes for NPC.

CONCLUSION

The NPC methylome shows a special high-degree CpG methylation epigenotype, similar to the Epstein-Barr virus-infected gastric cancer, indicating a critical epigenetic etiology for NPC pathogenesis.

Essential versus accessory aspects of cell death: recommendations of the NCCD 2015

Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as ‘accidental cell death' (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. ‘Regulated cell death' (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death.

Infections and inflammatory bowel disease: challenges in Asia

The diagnosis and management of inflammatory bowel disease (IBD) in Asia can be challenging as certain infections can mimic IBD and lead to a misdiagnosis. Colitis can be caused by bacterial infections, ileitis can result from Yersinia and Salmonella infections and ileocolonic ulcers can be seen in intestinal tuberculosis and amebiasis. In addition, cytomegalovirus and Clostridium difficile infection may mimic a flare of IBD and their presence is associated with an increased risk of colectomy and mortality. Because of the increasing use of corticosteroids, immunosuppressive drugs and biological agents the risk of opportunistic infection and the reactivation of latent infection including tuberculosis and hepatitis B, are also higher in IBD patients. Screening and prevention of infection, timely vaccination and the education of the patient is paramount before initiating immunosuppressive drugs. The role of the physician lies not only in the diagnosis and management of IBD but also in the ability to prevent, recognize and treat infections.

Statements of the Malaysian Society of Gastroenterology & Hepatology and the National Heart Association of Malaysia task force 2012 working party on the use of antiplatelet therapy and proton pump inhibitors in the prevention of gastrointestinal bleeding

The working party statements aim to provide evidence and guidelines to practising doctors on the use of antiplatelet therapy and proton pump inhibitors (PPIs) in patients with cardiovascular risk as well as those at risk of gastrointestinal (GI) bleeding. Balancing the GI and cardiovascular risk and benefits of antiplatelet therapy and PPIs may sometimes pose a significant challenge to doctors. Concomitant use of anti-secretory medications has been shown to reduce the risk of GI bleeding but concerns have been raised on the potential interaction of PPIs and clopidogrel. Many new data have emerged on this topic but some can be confusing and at times controversial. These statements examined the supporting evidence in four main areas: rationale for antiplatelet therapy, risk factors of GI bleeding, PPI-clopidogrel interactions and timing for recommencing antiplatelet therapy after GI bleeding, and made appropriate recommendations.

Endoscopic submucosal dissection for colonic lesions: why and how should we do it?

Endoscopic submucosal dissection (ESD) is a safe and effective alternative to surgery for large non-polypoid colonic lesions and early colorectal carcinoma. In this article, we discuss the development, efficacy and safety of ESD. As the incidence of colorectal cancer is rapidly increasing in Asia, we advocate standardization of ESD program, including patient selection, hardware prerequisites, and training of operators.

Evaluation of replacing the existing diagnostic strategy for Neisseria gonorrhoeae and Chlamydia trachomatis infections with sole molecular testing of urine specimens in a sexually transmitted infection clinic setting

OBJECTIVES

To evaluate nucleic acid testing of urine specimens against conventional Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) tests in genital swab specimens in a sexually transmitted infection (STI) clinic setting.

METHODS

Genital swab and urine samples were collected from attendees of public STI clinics in Hong Kong from May to June 2007. Swab specimens were subjected to on-site Gram stained microscopy and inoculation onto modified Thayer-Martin medium for NG culture before laboratory processing. CT PCR on genital swabs was performed by the Roche Cobas Amplicor test. Urine samples were tested for CT and NG by the Aptima Combo 2 (AC2) assay.

RESULTS

Data from 414 patients were analysed. The sensitivity and specificity of AC2 for NG were 100% (35/35) and 98.4% (373/379), respectively, with culture of genital swab specimens as standard. On-site microscopy provided timely results for empirical antimicrobial therapy, whereas culture yielded bacterial isolates for susceptibility testing and typing studies. Regarding CT, using Amplicor on genital swab specimens as reference, the sensitivity and specificity of AC2 were 98.7% (78/79) and 97.5% (313/321), respectively. Amplicor yielded uninterpretable results in 14 specimens due to PCR inhibitors.

CONCLUSIONS

The current STI clinic and laboratory practices were practical and useful for clinical management, even though favourable results were obtained with the AC2 assay, which had streamlined laboratory workflow. The use of a molecular testing strategy may be cost-effective with microscopy and culture being targetted for patient groups with the highest expected yield of positive results.

Comparison of two new rapid serology tests for diagnosis of Helicobacter pylori infection in Chinese patients

BACKGROUND

Rapid serology test is a simple and convenient way for diagnosing Helicobacter pylori infection. However performances of these tests are usually less satisfactory than expected, particularly in developing countries.

AIM

To evaluate the performances of two newly developed rapid serology tests for Helicobacter pylori infection.

PATIENTS

Consecutive Chinese dyspeptic patients undergoing upper gastrointestinal endoscopy.

METHODS

Gastric biopsies were obtained from antrum and corpus for rapid urease test and histological examination. Diagnosis of Helicobacter pylori infection was based on two or more positive results in rapid urease test, histology and [13C] urea breath test. Patients' sera were tested against two rapid serology tests: ASSURE Hp Rapid Test (Genelabs Diagnostics, Singapore) and SureStep (Applied Biotech, San Diego, CA, USA).

RESULTS

A total of 148 patients were evaluated and Helicobacter pylori infection was diagnosed in 78 (53%) patients by gold standard. The sensitivities of ASSURE Hp and SureStep were, respectively, 94% and 71% (p=0.0003). Specificities of the two test kits were both 90%. The overall accuracy of ASSURE Hp was significantly higher than SureStep (92% versus 80%, p=0.004).

CONCLUSION

Both rapid serology tests appear to be specific in diagnosing Helicobacter pylori infection in the Chinese populations. However the ASSURE Hp test is more sensitive and accurate than the SureStep test.

Alterations of frizzled (FzE3) and secreted frizzled related protein (hsFRP) expression in gastric cancer

Wnt signaling pathway is important for development and carcinogenesis. Alterations of this pathway, such as mutations in adenomatous polyposis coli (APC) gene and activation mutations of beta-catenin, would result in stabilization of beta-catenin and subsequent translocation to nucleus where genes are transcribed. Recently, a receptor of Wnt, FzE3 was found to be up-regulated in esophageal carcinoma while a non-receptor antagonist of Wnt, secreted frizzled related protein (hsFRP) was found to be down-regulated in some cancer. These findings suggested that FzE3 is a potential oncogene while hsFRP is a potential tumor suppressor gene. We aimed to investigate whether FzE3 and hsFRP were altered in gastric cancer. Twelve cases of gastric cancer, including 7 cases of intestinal type, 4 cases of diffuse type and I case of mixed type, were studied. FzE3 and hsFRP mRNAs were expressed in most of the paired normal gastric tissues. FzE3 was over-expressed in 9 cases (75%) of gastric carcinoma tissues while hsFRP was down-regulated in 2 cases (16%). Beta-catenin nuclear staining was identified in 3 cases (27%) and cyclin D1 was expressed in 5 cases (41%) of cancer samples. All these cases were associated with either up-regulation of FzE3 or down-regulation of hsFRP. Our results suggested that alterations of FzE3 or hsFRP were frequent in gastric cancer. These provide alternative mechanisms leading to activation of Wnt signaling pathway in gastric carcinogenesis.

Helicobacter pylori and nonsteroidal anti-inflammatory drugs

The complex interaction between H. pylori and NSAIDs implies that it is over simplistic to conclude that their relationship is independent, synergistic, or antagonistic without considering the influence of other factors. Factors such as previous exposure to NSAIDs, a history of ulcer complication, concurrent use of acid-suppressant therapy, and the difference between NSAIDs and low-dose aspirin all affect the outcome. Several recommendations can be made with regard to the indications of H. pylori eradication for patients requiring NSAIDs. First, patients taking NSAIDs who have ulcers or previous ulcer disease should be tested for the bacterium, and it should be eradicated if present because it is impossible to determine whether the ulcers are caused by H. pylori or NSAIDs or both. Antiulcer drugs should be prescribed to prevent ulcer recurrence for patients who continue to require NSAIDs. Although the efficacy of omeprazole is enhanced by H. pylori infection, it is not justified to leave a pathogen in the stomach in exchange for a modest therapeutic gain. Second, for patients who take low-dose aspirin, eradication of H. pylori substantially reduces the risk of ulcer bleeding. It is advisable that patients taking low-dose aspirin who are at risk of ulcer bleeding should be tested for H. pylori and treated for it if the infection is found. Third, for patients who are about to start NSAIDs, screen-and-treat H. pylori has the potential of reducing the ulcer risk at an affordable incremental cost. It might be argued that any interaction between H. pylori and NSAIDs would become irrelevant in the era of COX-2-selective NSAIDs. Even among patients who are receiving a COX-2-selective NSAID, however, a large-scale study showed that the ulcer risk is significantly higher in H. pylori-positive patients than in uninfected patients. This finding suggests that the relative importance of H. pylori in ulcer development might increase with a reduced toxicity of COX-2-selective NSAIDs. With an increasing use of low-dose aspirin for cardiovascular prophylaxis, the problem of aspirin-related ulcer disease is expected to rise. Given the significant role of H. pylori in the latter condition, screen-and-treat H. pylori might be a useful strategy for the prevention of ulcer complications in high-risk patients receiving low-dose aspirin in the future.

Dysfunction of oesophageal motility in Helicobacter pylori-infected patients with reflux oesophagitis

BACKGROUND

Helicobacter pylori infection has been suggested to be protective against gastro-oesophageal reflux disease. However, a significant proportion of patients with gastro-oesophageal reflux disease are infected by H. pylori.

AIM

To study oesophageal motor function in H. pylori-infected patients with reflux oesophagitis.

METHODS

Patients with erosive reflux oesophagitis were recruited prospectively for stationary oesophageal manometry and 24-h ambulatory oesophageal pH monitoring. H. pylori status was determined by biopsy urease test. Non-reflux volunteers were recruited as controls.

RESULTS

Seventy-four patients with erosive oesophagitis (34 H. pylori-positive, 40 H. pylori-negative) and 48 non-reflux patient controls (22 H. pylori-positive, 26 H. pylori-negative) were recruited. There was no difference in severity of oesophagitis (median grade, 1; P=0.53) or oesophageal acid exposure (total percentage time oesophageal pH < 4, 7.6% vs. 6.8%; P=0.57) between H. pylori-positive and H. pylori-negative groups. Compared to H. pylori-negative patients, H. pylori-positive patients had significantly lower basal lower oesophageal sphincter pressure (12.2 mmHg vs. 15.3 mmHg; P=0.03) and amplitude of distal peristalsis (56.9 mmHg vs. 68.4 mmHg; P=0.03). Ineffective oesophageal motility (14% vs. 7%; P=0.02) and failed oesophageal peristalsis were also significantly more prevalent in H. pylori-positive patients.

CONCLUSIONS

Among patients with a similar degree of reflux oesophagitis, H. pylori-infected patients have more severe oesophageal dysmotility and lower oesophageal sphincter dysfunction. Oesophageal motor dysfunction probably plays a dominant role in the development of gastro-oesophageal reflux disease in patients with H. pylori infection.

Lamivudine treatment for fulminant hepatic failure due to acute exacerbation of chronic hepatitis B infection

BACKGROUND

Exacerbation of chronic hepatitis B infection can lead to fulminant hepatic failure with a mortality of up to 90%.

AIM

To evaluate the efficacy of lamivudine in the treatment of this subgroup of patients.

METHODS

Twenty-four patients with exacerbation of chronic hepatitis B infection and fulminant hepatic failure were treated with lamivudine, 100 mg daily. Hepatitis A, C, D and human immunodeficiency virus co-infections and hepatocellular carcinoma were excluded.

RESULTS

The median age was 53 years (range, 24-77 years) with a male predominance of 20:4. Seventeen patients were hepatitis B e antigen positive. Mean hepatitis B virus DNA was 2079 Meq/mL. Eight patients (33%) survived (group A). Thirteen patients died and three patients received liver transplantation (67%) (group B). Baseline laboratory results were comparable between the two groups, including serum albumin, bilirubin, alanine aminotransferase, prothrombin time and creatinine. Group B patients had significantly more comorbid illnesses at baseline and more complications, including sepsis and renal failure, compared with group A patients. Six out of eight survivors (75%) had full hepatitis B e antigen seroconversion, but this was not sustained in four patients.

CONCLUSIONS

Lamivudine may be useful in treating patients with fulminant hepatic failure due to exacerbation of chronic hepatitis B. Hepatitis B e antigen seroconversion was less durable in this subgroup of patients and long-term therapy may be required.

Incidence of gastroesophageal malignancy in patients with dyspepsia in Hong Kong: implications for screening strategies

BACKGROUND

A "test-and-treat" strategy for H pylori infection has been recommended in Europe and North America as safe and cost-effective for management of patients with dyspepsia. The primary aim of this study was to determine the frequency of gastroesophageal cancer in 2 groups of patients with dyspepsia: those 45 years of age or younger without "alarm" symptoms (low-risk group) and patients over 45 years of age or any patient with "alarm" symptoms (high-risk group). A secondary aim was to determine the frequency of gastric cancer among patients in the low-risk group with or without a positive serology for H pylori.

METHODS

Patients with persistent dyspepsia were recruited from 4 regional hospitals in Hong Kong. Those in the low-risk group were evaluated for H pylori by using a whole blood serology test; they underwent endoscopy within 1 week. Those in the high-risk group and those taking nonsteroidal anti-inflammatory drugs (NSAIDs) underwent endoscopy promptly. Alarm symptoms were as follows: weight loss (10 or more pounds over 8 weeks), recurrent vomiting, dysphagia, bleeding, or anemia.

RESULTS

Of 2627 patients enrolled, 1017 were in the low-risk group and 1610 in the high-risk group. Twenty-three patients (0.9%) had gastroesophageal cancers (20 gastric, 3 esophageal). Four patients with cancer (17.4%) were in the low-risk group (3 gastric, 1 esophageal); all except the patient with esophageal cancer had a positive serology test. In the high-risk group, 19 patients had cancer (17 gastric, 2 esophageal).

CONCLUSION

Gastric cancer is relatively frequent among young patients with dyspepsia who have no alarm features in Hong Kong. This finding raises concerns as to the safety of the "test-and-treat" strategy for the management of patients with dyspepsia in Asia.

Apoptosis and proliferation in Helicobacter pylori-associated gastric intestinal metaplasia

BACKGROUND

Imbalance between apoptosis and proliferation may be one of the mechanisms underlying H. pylori associated gastric carcinogenesis.

AIM

To examine the cell kinetics of gastric intestinal metaplasia and the effect of H. pylori eradication.

METHODS

Endoscopic gastric biopsies were obtained from 100 H. pylori-infected patients. Apoptosis was determined by triphosphate nick-end labelling (TUNEL) and apoptotic nuclei counting, whereas proliferation was assessed by Ki67 immunostaining. Gastric biopsies were repeated in a sub-group of intestinal metaplasia patients after H. pylori eradication.

RESULTS

Antral apoptotic index was significantly lower in intestinal metaplasia than in non-intestinal metaplasia (0.19% vs. 0.51%; P < 0.0001) whereas the level of proliferation was comparable (28% vs. 22%, P=0.15). Serial antral biopsies taken from 14 intestinal metaplasia patients before and 1 year after H. pylori eradication showed a significant drop in proliferation in both intestinal metaplasia (50% vs. 12%, P < 0.001) and non-intestinal metaplasia area (47% vs. 9%, P < 0.001). A similar fall in apoptosis was detected in non-metaplastic region (0.58% vs. 0.38%, P < 0.001) but not in intestinal metaplasia (0.24% vs. 0.27%, P=0.56), resulting in a significant increase in the apoptosis/proliferation ratio (0.005-0.021; P=0.03).

CONCLUSIONS

Dysregulation in apoptosis control of gastric intestinal metaplasia may contribute to gastric carcinogenesis, which may be retarded by clearance of H. pylori.

Effect of Helicobacter pylori eradication on expression of cyclin D2 and p27 in gastric intestinal metaplasia

BACKGROUND AND AIMS

Cyclins and cyclin-dependent kinase inhibitors play a crucial role in the control of cell cycle transitions. Enhanced expression of cyclin D2 and reduced expression of p27kip1 (p27) have been implicated in the pathogenesis of cancer. Because intestinal metaplasia has been regarded as a pre-malignant lesion, we investigated the expression of cyclin D2 and p27 in Helicobacter pylori-associated chronic gastritis with and without intestinal metaplasia, and followed the changes after H. pylori eradication.

METHODS

Expression of cyclin D2 and p27 was studied by immunohistochemistry in 59 patients (including 35 patients with intestinal metaplasia) and in 10 gastric cancer patients. Among them, 29 H. pylori-infected patients had serial gastric biopsies taken before and at 1-year after eradication of H. pylori.

RESULTS

Expression of cyclin D2 was significantly higher in gastric cancers when compared to their adjacent non-tumour tissues (median score 3 vs. 1, P=0.015). Over-expression of cyclin D2 was detected in H. pylori-associated chronic gastritis and intestinal metaplasia, which was reduced after eradication of the organism (median score 2 vs. 1, P=0.037 in chronic gastritis; median score 2 vs. 0, P=0.008 in intestinal metaplasia). While the normal gastric mucosa showed strong p27 expression, five of the 10 gastric cancer tissues exhibited reduced p27 expression (P=0.039). Diminished p27 expression was also seen in intestinal metaplasia, which was restored 1-year after H. pylori eradication (eight out of 16 vs. one out of 16, P=0.018). Reduced expression of p27 was frequently associated with increased cyclin D2 expression in H. pylori-associated intestinal metaplasia (P=0.02).

CONCLUSION

Over-expression of cyclin D2 and reduced expression of p27 are closely linked to H. pylori-associated intestinal metaplasia. Eradication of H. pylori infection reverses the aberrant expression of cyclin D2 and p27 in intestinal metaplasia.

Fluorescence resonance energy transfer analysis of cell surface receptor interactions and signaling using spectral variants of the green fluorescent protein

BACKGROUND

Fluorescence resonance energy transfer (FRET) is a powerful technique for measuring molecular interactions at Angstrom distances. We present a new method for FRET that utilizes the unique spectral properties of variants of the green fluorescent protein (GFP) for large-scale analysis by flow cytometry.

METHODS

The proteins of interest are fused in frame separately to the cyan fluorescent protein (CFP) or the yellow fluorescent protein (YFP). FRET between these differentially tagged fusion proteins is analyzed using a dual-laser FACSVantage cytometer.

RESULTS

We show that homotypic interactions between individual receptor chains of tumor necrosis factor receptor (TNFR) family members can be detected as FRET from CFP-tagged receptor chains to YFP-tagged receptor chains. Noncovalent molecular complexation can be detected as FRET between fusions of CFP and YFP to either the intracellular or extracellular regions of the receptor chains. The specificity of the assay is demonstrated by the absence of FRET between heterologous receptor pairs that do not biochemically associate with each other. Interaction between a TNFR-like receptor (Fas/CD95/Apo-1) and a downstream cytoplasmic signaling component (FADD) can also be demonstrated by flow cytometric FRET analysis.

CONCLUSIONS

The utility of spectral variants of GFP in flow cytometric FRET analysis of membrane receptors is demonstrated. This method of analyzing FRET allows probing of noncovalent molecular interactions that involve both the intracellular and extracellular regions of membrane proteins as well as proteins within the cells. Unlike biochemical methods, FRET allows the quantitative determination of noncovalent molecular associations at Angstrom level in living cells. Moreover, flow cytometry allows quantitative analyses to be carried out on a cell-by-cell basis on large number of cells. Published 2001 Wiley-Liss, Inc.

Inverse association between cyclooxygenase-2 overexpression and microsatellite instability in gastric cancer

This study examined the association between cyclooxygenase-2 (COX-2) overexpression and microsatellite instability (MSI) in gastric cancer. COX-2 expression was assessed by immunohistochemistry and scored in a semi-quantitative manner whereas MSI status was characterized by nine microsatellite markers. The clinicopathological features of cancers including survival data were analyzed. Of the 109 gastric cancers studied, COX-2 overexpression and high level of MSI (MSI-H) was detected in 64.2 and 22.0% cases respectively. Gastric tumors with MSI-H phenotypes had significantly lower level of COX-2 expression levels when compared to MSI-L and MSS tumors (P=0.002). Moreover, COX-2 overexpression was associated with tumor invasion beyond submucosa (P=0.045) and there was a trend favoring better survival in gastric cancers without COX-2 overexpression (P=0.07). The results from this study suggest that gastric cancer with microsatellite instability or COX-2 overexpression present with diverse clinicopathological features.

Role of acid suppressants in prophylaxis of NSAID damage

Gastric acid contributes to the pathogenesis of non-steroidal anti-inflammatory drug (NSAID)-induced ulceration via several mechanisms, including conversion of superficial to deeper injury, impairment of haemostasis, and interference with ulcer healing. The suppression of acid secretion has been shown to reduce the severity of NSAID-induced mucosal damage in experimental models and clinical studies. Current evidence indicates that proton pump inhibitors (PPIs) are the preferred treatment for the healing of gastric ulcers when NSAIDs cannot be discontinued. PPIs are superior to standard-dose H(2)-receptor antagonists and equivalent to low-dose misoprostol in preventing NSAID-induced gastric ulcers. Whether there is any significant advantage of PPIs over higher doses of H(2)-receptor antagonists or misoprostol is unknown. The efficacy of PPIs is enhanced in the presence of H. Pylori infection. Omeprazole has been shown to be effective for the secondary prevention of ulcer bleeding in H. pylori -infected NSAID users. The efficacy of PPIs for the prevention of ulcer complications in H. pylori-negative NSAID users remains uncertain.

Is non-Helicobacter pylori, non-NSAID peptic ulcer a common cause of upper GI bleeding? A prospective study of 977 patients

BACKGROUND

Non-Helicobacter pylori, non-NSAID ulcer is relatively common in Western countries. Whether it is a significant problem in the Orient is unclear. The aim of this study was to investigate the incidence of non-H pylori, non-NSAID ulcers presenting with GI bleeding.

METHODS

A prospective study was done of 1675 consecutive patients presenting with upper GI bleeding over a period of 12 months. Upper endoscopy was performed with biopsy specimens taken from the antrum and body of the stomach for a biopsy urease test (BUT) and histology for detection of H pylori. Exposure to nonsteroidal anti-inflammatory drugs (NSAID) or aspirin within 4 weeks of hospitalization was carefully scrutinized. A 6-week course of treatment with an H2-receptor antagonist was prescribed for patients who did not use an NSAID and had a negative BUT result. Follow-up endoscopy was performed to confirm H pylori status with a BUT and histology. Positive histology at either initial or follow-up endoscopy was used as the standard for diagnosing H pylori infection.

RESULTS

Among 977 patients who were found to have ulcer bleeding, 434 (44%) had exposure to aspirin or an NSAID. Of the 543 non-NSAID users, 431 (79.4%) had a positive BUT and 112 (20.6%) were BUT negative on initial endoscopy. Eighty-nine of 112 patients who were NSAID negative, BUT negative returned for follow-up endoscopy. Forty-nine of 89 (55.1%) were found to have a positive BUT and positive histology at follow-up endoscopy. Only 40 of 977 (4.1%) patients admitted with ulcer bleeding were confirmed to have non-H pylori, non-NSAID ulcers.

CONCLUSIONS

Non-H pylori, non-NSAID bleeding ulcer is uncommon. A negative BUT is unreliable for exclusion of H pylori infection during the acute phase of ulcer bleeding.

Preventing recurrent upper gastrointestinal bleeding in patients with Helicobacter pylori infection who are taking low-dose aspirin or naproxen

BACKGROUND

Many patients who have had upper gastrointestinal bleeding continue to take low-dose aspirin for cardiovascular prophylaxis or other non-steroidal antiinflammatory drugs (NSAIDs) for musculoskeletal pain. It is uncertain whether infection with Helicobacter pylori is a risk factor for bleeding in such patients.

METHODS

We studied patients with a history of upper gastrointestinal bleeding who were infected with H. pylori and who were taking low-dose aspirin or other NSAIDs. We evaluated whether eradication of the infection or omeprazole treatment was more effective in preventing recurrent bleeding. We recruited patients who presented with upper gastrointestinal bleeding that was confirmed by endoscopy. Their ulcers were healed by daily treatment with 20 mg of omeprazole for eight weeks or longer. Then, those who had been taking aspirin were given 80 mg of aspirin daily, and those who had been taking other NSAIDs were given 500 mg of naproxen twice daily for six months. The patients in each group were then randomly assigned separately to receive 20 mg of omeprazole daily for six months or one week of eradication therapy, consisting of 120 mg of bismuth subcitrate, 500 mg of tetracycline, and 400 mg of metronidazole, all given four times daily, followed by placebo for six months.

RESULTS

We enrolled 400 patients (250 of whom were taking aspirin and 150 of whom were taking other NSAIDs). Among those taking aspirin, the probability of recurrent bleeding during the six-month period was 1.9 percent for patients who received eradication therapy and 0.9 percent for patients who received omeprazole (absolute difference, 1.0 percent; 95 percent confidence interval for the difference, -1.9 to 3.9 percent). Among users of other NSAIDs, the probability of recurrent bleeding was 18.8 percent for patients receiving eradication therapy and 4.4 percent for those treated with omeprazole (absolute difference, 14.4 percent; 95 percent confidence interval for the difference, 4.4 to 24.4 percent; P=0.005).

CONCLUSIONS

Among patients with H. pylori infection and a history of upper gastrointestinal bleeding who are taking low-dose aspirin, the eradication of H. pylori is equivalent to treatment with omeprazole in preventing recurrent bleeding. Omeprazole is superior to the eradication of H. pylori in preventing recurrent bleeding in patients who are taking other NSAIDs.

Validation of a new immunoblot assay for the diagnosis of Helicobacter pylori in the Asian population

BACKGROUND

Performance of commercial serological tests for Helicobacter pylori varies in different populations, largely due to strain heterogeneity and variations in antigenic preparations. Currently available serology tests often show sub-optimal accuracy when used for Asian patients.

AIM

This study evaluated a recombinant antigen-based immunoblot for the diagnosis of H. pylori infection in Chinese patients, and compared it with a conventional ELISA test.

METHODS

Dyspeptic patients referred for diagnostic endoscopy were recruited. The gold standard for H. pylori infection was based on two or more positive results among rapid urease test, histology and (13)C-urea breath test. Serological diagnosis of H. pylori infection was conducted by an ELISA test (pylori DTect; Diagnostic Technology) and an immunoblotting against a novel recombinant antigen (C1S; Genelab), which was constructed by immunological screening of the genomic DNA library of H. pylori.

RESULTS

A total of 87 patients were evaluated and H. pylori infection was diagnosed in 40 (46%) by the reference tests. The sensitivities of the ELISA and immunoblot were 80% (95% CI: 64--91%) and 90% (95% CI: 76--97%), whilst the specificities were 96% (95% CI: 86--96%) and 87% (95% CI: 74--95%), respectively. The respective likelihood ratios of the two tests were 18.6 and 7.0.

CONCLUSIONS

Satisfactory performance is obtained by the use of the new recombinant antigen-based immunoblot for diagnosing H. pylori infection in Chinese patients.

Somatic beta-catenin mutation in gastric carcinoma--an infrequent event that is not specific for microsatellite instability

We screened 90 cases of gastric carcinoma (GCA) samples for beta-catenin exon 3 mutation and assessed its possible relationship with microsatellite instability (MSI). Three mutations were detected in two samples, including a single mutation in an intestinal type and double mutations in a diffuse type GCA. One of the mutations found in the diffuse type GCA sample was a non-sense mutation at codon 68 (CAG-->TAG). This novel mutation was predicted to disrupt the binding of beta-catenin to alpha-catenin and may be related to the diffuse type morphology. The other two mutations were missense mutations involved or related to the GSK-3beta phosphorylation site, which have been reported previously. No MSI can be demonstrated in the two cases with beta-catenin mutation. Our results suggested that beta-catenin mutation was infrequent in GCA and appeared not specific for MSI.

Expression and cellular localization of COX-1 and -2 in Helicobacter pylori gastritis

BACKGROUND

There are conflicting reports on the expression of cyclooxygenase in Helicobacter pylori infection.

AIM

To evaluate the expression of COX-1 and COX-2 in H. pylori gastritis at messenger RNA (mRNA) and protein levels.

METHODS

Endoscopic gastric biopsies were obtained from patients with non-ulcer dyspepsia. The levels of COX-1 and COX-2 mRNA were compared between H. pylori-infected and uninfected specimens using reverse transcription-polymerase chain reaction. The immunohistochemical findings were correlated with the cellular localization of cyclooxygenase mRNA using in situ hybridization.

RESULTS

A total of 40 H. pylori-infected and 40 uninfected specimens were studied. mRNA of COX-2 but not COX-1 was elevated in H. pylori-infected mucosa. COX-1 was localized to the mononuclear inflammatory, endothelial and smooth muscle cells in the lamina propria. COX-2 was barely detectable in uninfected mucosa but was strongly expressed in the foveolar and glandular epithelia in H. pylori gastritis.

CONCLUSION

Cyclooxygenase-1 is expressed in the mononuclear inflammatory, endothelial and smooth muscle cells in the lamina propria irrespective of the H. pylori status. By contrast, H. pylori induces COX-2 expression in the foveolar and glandular epithelia.

Association between cyclo-oxygenase-2 overexpression and missense p53 mutations in gastric cancer

Wild-type p53 competitively binds to the promoter region of COX-2 in vitro and inhibits its transcription. We examined the association between p53 mutation and COX-2 expression in gastric cancer. COX-2 over-expression was seen in 19 (48.7%) cases. These tumours had more lymph-node metastasis (P = 0.048) and tended to have a poorer survival (P = 0.07). Missense mutations of p53 were detected in 20 (51.3%) patients and had a significantly stronger COX-2 expression than tumours without p53 mutation (P = 0.016). Our results suggest a link between p53 mutation and COX-2 overexpression in gastric cancer.

Helicobacter pylori infection in Chinese subjects with type 2 diabetes

The relationship between diabetes and Helicobacter pylori (HP) infection is controversial. In this study, we examined the possible relationship between HP infection and type 2 diabetes in Chinese subjects. Sixty-three Chinese type 2 diabetic patients (mean age +/- SD: 49.9 +/- 12.0 years; range: 17-76 years) were recruited irrespective of the duration of diabetes or type of therapy. Twenty-nine (46%) of them had upper gastrointestinal symptoms and the other 34 (54%) did not. Another 55 age- and sex-matched non-diabetic subjects (mean age +/- SD: 45.6 +/- 15.6 years, p=0.098; range 18-79 years) with dyspepsia indicated for upper endoscopy were recruited as a comparison group. Upper endoscopy was performed with antral mucosal biopsy specimens taken for rapid urease test (CLO test). HP infection was considered to be present if the rapid urease test was positive. The rates of HP infection of the diabetic and non-diabetic individuals were 50.8% and 56.4% respectively (p: NS). The rate of HP infection was similar between the 2 groups of diabetic patients with or without gastrointestinal symptoms (42.9% vs. 56.3%, p: NS). Using logistic regression analysis (forward stepwise) with age, sex, glycaemic control, duration of diabetes and upper gastrointestinal symptoms as independent variables to predict the risk of HP infection in diabetic patients, none of the parameters enter into the model. In conclusion, the rate of HP infection in Hong Kong Chinese subjects with type 2 diabetes is around 50%, which is similar to control subjects. No association was found between HP infection, glycaemic status, and duration of diabetes and upper gastrointestinal symptoms in these diabetic subjects.

Up-regulation of cyclooxygenase-1 and -2 in human gastric ulcer

BACKGROUND

The expression of cyclooxygenase (COX) in human gastric ulcers is unknown.

AIM

To study the expression and cellular localization of cyclooxygenase in human gastric ulcers.

METHODS

A total of 38 surgical gastric ulcer specimens were studied; 20 were Helicobacter pylori-positive and 18 were associated with NSAID use. Twenty non-ulcerated, histologically normal gastric specimens were used as controls. The cellular localization of COX-1 and COX-2 were determined by immunohistochemistry and double immunofluorescence. Cyclooxygenase messenger RNA (mRNA) was measured by reverse transcription-polymerase chain reaction and localized by in situ hybridization.

RESULTS

In control specimens, COX-1 was detected in stromal cells in the lamina propria. There was focal and weak immunostaining for COX-2 in the foveolar epithelium. At the ulcer edge, COX-1 was significantly increased in lamina propria cells whereas COX-2 was strongly expressed in the hyperplastic foveolar epithelium in H. pylori- and non-steroidal anti-inflammatory drugs (NSAID)-associated ulcers. At the ulcer base, there was strong expression of COX-1 and COX-2 in myofibroblasts, macrophages and endothelial cells in the granulation tissue, irrespective of H. pylori status or NSAID use. Messenger RNA of COX-1 and COX-2 were demonstrated by reverse transcription-polymerase chain reaction. Double immunofluorescence and in situ hybridization confirmed the cellular localization of cyclooxygenase at protein and mRNA levels, respectively.

CONCLUSION

Both COX-1 and COX-2 are up-regulated in human gastric ulcers.

Randomized trial of low-dose misoprostol and naproxen vs. nabumetone to prevent recurrent upper gastrointestinal haemorrhage in users of non-steroidal anti-inflammatory drugs

BACKGROUND

Prophylactic misoprostol or non-steroidal anti-inflammatory drugs (NSAIDs) with low gastric toxicity (nabumetone) has been shown to reduce mucosal injury.

AIM

To compare nabumetone vs. co-therapy of naproxen with low-dose misoprostol for secondary prevention of upper gastrointestinal bleeding in NSAID users.

METHODS

NSAID users presenting with upper gastrointestinal bleeding were enrolled if they required long-term NSAIDs. After ulcer healing, they were randomized to receive: naproxen (500-1000 mg/day) and misoprostol (200 microg b.d.), or nabumetone (1000-1500 mg/day) and placebo misoprostol for 24 weeks. The primary end-point was recurrent upper gastrointestinal bleeding. The secondary end-point was the proportion of patients suffering from major gastrointestinal events including ulcer bleeding, symptomatic ulcers and severe dyspepsia.

RESULTS

A total of 90 patients were included in the intention-to-treat analysis (misoprostol/naproxen 45, nabumetone 45). Recurrent bleeding occurred in 10 patients (22.2%) receiving misoprostol/naproxen compared with three (6.7%) receiving nabumetone (relative risk 3.33, 95% CI: 0.98-11.32, P=0.069). The proportion of patients suffering from major gastrointestinal events at 24 weeks was 31.1% in the misoprostol/naproxen group and 28.9% in the nabumetone group.

CONCLUSIONS

Misoprostol/naproxen is not superior to nabumetone for secondary prevention of upper gastrointestinal bleeding. Neither low-dose misoprostol nor nabumetone is adequate for high-risk NSAID users.

Risk factors for active liver disease in HBeAg-negative chronic hepatitis B virus-infected patients

OBJECTIVES

HBeAg-negative patients constitute approximately 70% of all chronic hepatitis B virus (HBV) infections in Southeast Asia, and some of these patients continue to suffer from active disease. We aimed to study the risk of hepatitis relapse in chronic HBV-infected patients with negative HBeAg and the predictor(s) of relapses.

METHODS

This was a retrospective analysis of patients carrying HBsAg but lacking HBeAg. Patients recruited were required to have been followed for > or = 12 months with a minimum of three blood samples available for analysis. Patient demographic data, liver biochemistry, and HBV serology were analyzed in relation to relapses of hepatitis. Relapse was defined as an abrupt elevation of ALT > 200 IU/L or > 3-fold previous levels, whichever was higher.

RESULTS

In a period of 3 months, 317 patients seen at the Hepatitis Clinic at the Prince of Wales Hospital in Hong Kong were recruited. The median duration of follow-up was 34 months. On initial consultation, 111 (35.0%) patients had elevated ALT (>60 IU/L). Overall, 57 (18.0%) patients developed at least one relapse, including 37 (33.3%) patients with elevated ALT and 20 (9.7%) patients with normal ALT at the first visit. Multiple logistic regression analysis showed that elevated ALT level at first presentation (odds ratio 4.17, 95% confidence interval 2.24-7.75) and male gender (odds ratio 2.83, 95% confidence interval 1.23-6.49) were the two independent factors associated with a higher risk of hepatitis relapse. The sensitivity, specificity, and positive and negative predictive values of a single ALT test for hepatitis relapse were 64.9%, 71.5%, 33.3%, and 90.3%, respectively.

CONCLUSIONS

HBeAg-negative HBV carriers with normal ALT levels have a low risk of hepatitis relapse.

The multifaceted role of Fas signaling in immune cell homeostasis and autoimmunity

Originally identified as a cell surface receptor that triggered the death of lymphocytes and tumor cells, it is now recognized that Fas (also known as CD95 or Apo-I) has distinct functions in the life and death of different cell types in the immune system. Fas signaling may also be involved in T cell costimulation and proliferation. Although Fas deficiency in humans and mice predisposes them towards systemic autoimmunity, Fas-FasL interactions can also facilitate organ-specific immunopathology. Proximal signaling by Fas and related receptors depends on subunit preassembly, which accounts for the dominant-negative effect of pathogenic receptor mutants and natural splice variants.

The pre-ligand binding assembly domain: a potential target of inhibition of tumour necrosis factor receptor function

Signalling by the tumour necrosis factor receptors (TNFR) is thought to be mediated by the binding of the trimeric ligand TNF to three monomeric subunits of the receptor. This ligand induced trimerisation model of TNFR signalling is mainly supported by crystallographic data of the p60 TNFR-1 and TNFbeta complex in which the trimeric ligand interdigitates between the individual receptor chains and prevents the receptor subunits from interacting with each other. Recently, a domain NH(2)-terminal to the ligand binding domain in the extracellular region of p60 TNFR-1, p80 TNFR-2 and Fas was identified that mediates receptor self association before ligand binding. This pre-ligand binding assembly domain or PLAD is critical for assembly of functional receptor complexes on the cell surface and may provide a potential target in the design of future novel therapeutics against diseases mediated by members of the TNFR family of receptors.

Non-steroidal anti-inflammatory drug toxicity in the upper gastrointestinal tract

Non-steroidal anti-inflammatory drug (NSAID) toxicity in the upper gastrointestinal tract is the most common serious drug-induced toxicity reported to drug regulatory authorities. In the last two decades, the rediscovery of H. pylori, development of potent ulcer-healing drugs and specific Cox-II inhibitors have opened new horizons in the management of NSAID toxicity. A Working Party composed of gastroenterologists and rheumatologists in the Asia-Pacific region met in Cairns, Australia, in 1999 to review the literature and develop appropriate guidelines. Recommendations were made based on the latest existing evidence. The importance of clinical events as study endpoints was emphasized. While differences exist between NSAIDs and aspirin, most studies have shown that advanced age, history of peptic ulcer disease, serious concomitant illnesses and coprescription of NSAID/aspirin with anticoagulants and steroids are high risk factors. These patients should be considered for prophylactic anti-ulcer therapy. Helicobacter pylori infection may aggravate the toxicity of NSAIDs and, in selected cases, should be treated before NSAID/aspirin is prescribed. Proton pump inhibitors and misoprostol are the most promising agents in preventing gastric and duodenal ulcers. When NSAID/aspirin needs to be continued in patients who develop an NSAID-related ulcer, proton pump inhibitors offer the best healing effect. With the discovery of cyclo-oxygenase isoforms (Cox-I and Cox-II), preferential and specific Cox-II inhibitors have been developed. While early clinical data have suggested promising antiinflammatory effects and improved safety profile in the gastrointestinal tract, several key issues on long-term safety remain unresolved. The use of potent anti-ulcer therapy, treatment of H. pylori infection and the development of Cox-II inhibitor will change the scenario of NSAID/aspirin-related gastrointestinal toxicity in the next millennium.

Cyclooxygenase-2 expression in Helicobacter pylori-associated premalignant and malignant gastric lesions

Expression of cyclooxygenase-2 (COX-2) in various stages of the Helicobacter pylori-associated gastric carcinogenesis pathway has not been elucidated. We investigated the distribution and intensity of COX-2 expression in premalignant and malignant gastric lesions, and monitored the changes after H. pylori eradication. Gastric biopsies from H. pylori-infected patients with chronic active gastritis, gastric atrophy, intestinal metaplasia (IM), gastric adenocarcinoma, and noninfected controls were studied. Expression of COX-2 was evaluated by immunohistochemistry and in situ hybridization. Endoscopic biopsies were repeated 1 year after successful eradication of H. pylori in a group of IM patients for comparing COX-2 expression and progression of IM. In all H. pylori-infected patients, COX-2 expression was predominantly found in the foveolar and glandular epithelium and, to a lesser extent, in the lamina propria. In the noninfected group, only 35% of cases demonstrated weak COX-2 expression. Intensity of COX-2 was not significantly different between the chronic active gastritis, gastric atrophy, IM, and gastric adenocarcinoma groups. In 17 patients with IM, COX-2 expressions in the epithelial cells and stromal cells were reduced 1 year after H. pylori eradication. However, the changes in COX-2 expression did not correlate with progression/regression of IM. Both premalignant and malignant gastric lesions demonstrate strong COX-2 expression. Successful eradication of H. pylori leads to down-regulation of COX-2 expression but failed to reverse IM at 1 year.

A case of giant malignant phaeochromocytoma

Malignant phaeochromocytoma is defined as the presence of tumour deposits at sites that are normally devoid of chromaffin cells. We report on a 63-year-old man who had a giant malignant phaeochromocytoma of the right adrenal gland that encased the inferior vena cava. The urinary excretion rates of catecholamines and their metabolites were normal, except for normetanephrine, which was excreted at a higher rate than normal. The tumour was surgically unresectable by laparotomy. Postoperatively, the patient was given a 4-month trial of subcutaneous octreotide and intravenous meta-iodobenzylguanidine I 131. Occult lung secondary tumours were first detected by meta-iodobenzylguanidine scintigraphy after 2 years, and the patient died of bone and lung metastases 1 year later. Because phaeochromocytoma is rare, local experience in managing this disease is limited. This report alerts physicians of the methods of diagnosing and managing surgically unresectable malignant phaeochromocytoma.

Effect of intravenous omeprazole on recurrent bleeding after endoscopic treatment of bleeding peptic ulcers

BACKGROUND

After endoscopic treatment of bleeding peptic ulcers, bleeding recurs in 15 to 20 percent of patients.

METHODS

We assessed whether the use of a high dose of a proton-pump inhibitor would reduce the frequency of recurrent bleeding after endoscopic treatment of bleeding peptic ulcers. Patients with actively bleeding ulcers or ulcers with nonbleeding visible vessels were treated with an epinephrine injection followed by thermocoagulation. After hemostasis had been achieved, they were randomly assigned in a double-blind fashion to receive omeprazole (given as a bolus intravenous injection of 80 mg followed by an infusion of 8 mg per hour for 72 hours) or placebo. After the infusion, all patients were given 20 mg of omeprazole orally per day for eight weeks. The primary end point was recurrent bleeding within 30 days after endoscopy.

RESULTS

We enrolled 240 patients, 120 in each group. Bleeding recurred within 30 days in 8 patients (6.7 percent) in the omeprazole group, as compared with 27 (22.5 percent) in the placebo group (hazard ratio, 3.9; 95 percent confidence interval, 1.7 to 9.0). Most episodes of recurrent bleeding occurred during the first three days, which made up the infusion period (5 in the omeprazole group and 24 in the placebo group, P<0.001). Three patients in the omeprazole group and nine in the placebo group underwent surgery (P=0.14). Five patients (4.2 percent) in the omeprazole group and 12 (10 percent) in the placebo group died within 30 days after endoscopy (P=0.13).

CONCLUSIONS

After endoscopic treatment of bleeding peptic ulcers, a high-dose infusion of omeprazole substantially reduces the risk of recurrent bleeding.

EUS-guided injection of cyanoacrylate for bleeding gastric varices

BACKGROUND

Bleeding gastric varices is a highly fatal condition. Recurrent bleeding after hemostasis achieved by endoscopic methods is common, and obliteration of gastric varices is difficult to assess. Our aim was to investigate the use of endosonography (EUS) in monitoring cyanoacrylate injection to obliterate gastric varices.

METHODS

Patients who presented with bleeding gastric varices were treated with bolus injection(s) of cyanoacrylate (0.5 mL cyanoacrylate mixed with 0.7 mL Lipiodol) until bleeding was controlled; 47 patients received "on-demand" injection only in response to recurrent bleeding (on-demand group). Another group of 54 patients underwent biweekly EUS followed by repeated injection of cyanoacrylate (repeated-injection group) until all gastric varices were obliterated. The primary outcome was recurrent bleeding-free interval and survival rate.

RESULTS

The two groups of patients were comparable demographically. Although the rates of early (</=48 hour) bleeding recurrence were similar with repeated or on-demand injection (7.4% versus 12.8%, p = 0.5), late recurrence of bleeding (>48 hour) was significantly reduced in the repeated-injection group (18.5% versus 44.7%, p = 0.0053, odds ratio 0.28 (95% CI [0.12, 0. 69]). Cumulative probability of recurrent bleeding-free interval was higher in the repeated-injection than the on-demand group (log-rank test, p = 0.0053). There was a numeric trend toward improved survival in the repeated-injection group.

CONCLUSION

Gastric varices obliteration with cyanoacrylate under EUS monitoring reduces recurrent bleeding and may improve survival.

Interaction of Helicobacter pylori eradication and non-steroidal anti-inflammatory drugs on gastric epithelial apoptosis and proliferation: implications on ulcerogenesis

BACKGROUND

Apoptosis is associated with loss of gastric mucosal integrity and may play an important role in ulcer development.

AIM

To examine how Helicobacter pylori and NSAIDs interact to effect apoptosis and proliferation of the gastric mucosa.

METHODS

Patients presenting with musculoskeletal pain requiring NSAID treatment and without previous exposure to NSAID or pre-existing ulcers were recruited. Patients were divided into three groups: (A) H. pylori-infected; (B) H. pylori-eradicated; and (C) non-infected patients. They were given naproxen for 8 weeks. Patients with non-ulcer dyspepsia and H. pylori infection who were given anti-Helicobacter therapy were recruited as controls (D). Endoscopy was performed at baseline and 8-weeks after receiving naproxen. Gastric antral biopsies were obtained to assess apoptosis by terminal uridine deoxynucleotidyl nick end-labelling (TUNEL) and proliferation by Ki67 immunostaining.

RESULTS

A total of 55 patients were studied. H. pylori-positive patients had a higher apoptosis and proliferation index at baseline than non-infected patients (P < 0.0001), and eradication of H. pylori resulted in a significant reduction in these parameters. The NSAID induced apoptosis in non-infected subjects (P=0.03) whilst apoptosis was reduced in H. pylori-positive patients receiving NSAID (P=0.02). After 8 weeks of NSAID, post-treatment apoptosis was significantly higher in patients with persistent H. pylori infection than in non-infected patients (P=0.01).

CONCLUSIONS

Eradication of H. pylori prior to NSAID therapy significantly reduces the level of apoptosis in the gastric mucosa, which may contribute to maintaining mucosa integrity and preventing ulcer development.

A domain in TNF receptors that mediates ligand-independent receptor assembly and signaling

A conserved domain in the extracellular region of the 60- and 80-kilodalton tumor necrosis factor receptors (TNFRs) was identified that mediates specific ligand-independent assembly of receptor trimers. This pre-ligand-binding assembly domain (PLAD) is physically distinct from the domain that forms the major contacts with ligand, but is necessary and sufficient for the assembly of TNFR complexes that bind TNF-alpha and mediate signaling. Other members of the TNFR superfamily, including TRAIL receptor 1 and CD40, show similar homotypic association. Thus, TNFRs and related receptors appear to function as preformed complexes rather than as individual receptor subunits that oligomerize after ligand binding.

Fas preassociation required for apoptosis signaling and dominant inhibition by pathogenic mutations

Heterozygous mutations encoding abnormal forms of the death receptor Fas dominantly interfere with Fas-induced lymphocyte apoptosis in human autoimmune lymphoproliferative syndrome. This effect, rather than depending on ligand-induced receptor oligomerization, was found to stem from ligand- independent interaction of wild-type and mutant Fas receptors through a specific region in the extracellular domain. Preassociated Fas complexes were found in living cells by means of fluorescence resonance energy transfer between variants of green fluorescent protein. These results show that formation of preassociated receptor complexes is necessary for Fas signaling and dominant interference in human disease.

Measurement of molecular interactions in living cells by fluorescence resonance energy transfer between variants of the green fluorescent protein

Many signal transduction pathways operate through oligomerization of proteins into multi-subunit complexes. Although biochemical assays can identify potential protein-protein interactions, studying these interactions in living cells is more challenging. Fluorescence resonance energy transfer (FRET) has been used as a "spectroscopic ruler" to measure molecular proximity, but these methods have been limited by the need for chemical labeling of target proteins or labeled antibodies. We present methods for examining interactions between target proteins molecularly fused to cyan and yellow variants of the green fluorescent protein (GFP) by FRET in living cells. Flow cytometric and microscope-based methods are described that have been applied to a variety of interacting proteins.

Helicobacter pylori infection is associated with milder gastro-oesophageal reflux disease

BACKGROUND

We have previously demonstrated a negative relationship between the prevalence of Helicobacter pylori and gastro-oesophageal reflux disease (GERD).

AIM

To study the effects of H. pylori infection on the severity of GERD.

METHODS

Ethnic Chinese patients with frequent heartburn and/or endoscopic oesophagitis were studied. Endoscopic examination was performed to assess the severity of oesophagitis (modified Savary-Miller grading) and the presence of hiatus hernia. Biopsies were taken for rapid urease testing and confirmation of Barrett's oesophagus. Risk factors which may affect the severity of oesophagitis (age, sex, smoking, drinking, diabetes mellitus, hiatus hernia, H. pylori status and body mass index) were evaluated by a multiple regression model. The cagA status of H. pylori infected GERD and age-and-sex matched controls were determined by Western blot. Age-and-sex matched non-reflux patients were recruited as controls for comparison.

RESULTS

Two hundred and twenty-five patients with GERD were studied, of whom 77 (34%) were infected with H. pylori. Oesophagitis and Barrett's oesophagus were found in 140 patients (62%) and six patients (3%), respectively. H. pylori infected patients had significantly less severe oesophagitis compared to the uninfected group (P=0.022). All patients with Barrett's oesophagus were uninfected. Factors that predicted severe oesophagitis included age over 60 years (P < 0.001) and hiatus hernia (P < 0.001). H. pylori infection was the only factor that showed a negative correlation with severe oesophagitis (P=0.011). The prevalence of the cagA positive strain in endoscopy-negative GERD, erosive oesophagitis and control subjects was 70, 76 and 78%, respectively (P=0.75).

CONCLUSIONS

H. pylori infection is associated with milder GERD.