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E K Ng

Publications and source records attributed to E K Ng.

At least 19 recordsLinked to original sources
PubMed2007

Trans-cutaneous electrogastrographic study of gastric myoelectric activity in transposed intrathoracic stomach after esophagectomy.

We examined the feasibility of trans-cutaneous electrogastrography (EGG) in recording myoelectric activity of the transposed thoracic stomach after esophagectomy. Nineteen patients who had Ivor-Lewis esophagectomy were studied. The EGG signal was recorded using cutaneous electrodes placed over the lower sternum. Eleven patients who underwent total gastrectomy served as controls. Normal rhythm pattern (2.4-3.6 cpm > or = 70%) and power ratio (PR > or = 2) was observed in five and 12 patients, respectively, after esophagectomy. The observation of normal gastric rhythm was more frequent in the postprandial period in the esophagectomy group (median 42.6%vs. 7.4%, P = 0.01), and the PR was significantly higher (median 2.27 vs. 1.38, P = 0.013) than the gastrectomy group. Feeding further increased the prevalence of normal gastric slow wave in the esophagectomy group (median 14.8% to 42.6%, P = 0.002) and improved the stability of dominant frequency (median 78% to 67%, P = 0.015). We conclude that gastric myoelectric activities of thoracic transposed stomach can be detected from cutaneous sternal electrodes. This represented a preservation of gastric motility even when the stomach is pulled up to the thorax as a substitute for the esophagus.

Case-Control Studies↗
PubMed2001

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.

Cohort Studies↗
PubMed2001

Concurrent hypermethylation of multiple tumor-related genes in gastric carcinoma and adjacent normal tissues.

BACKGROUND: Transcriptional silencing by CpG-island hypermethylation now is believed to be an important mechanism of tumorigenesis. To date, studies on CpG-island hypermethylation in gastric carcinoma and adjacent normal tissues are few. METHODS: The authors examined 5 gastric carcinoma cell lines, 26 frozen gastric carcinoma tissues and their adjacent nontumor area for concurrent CpG-island hypermethylation in 6 tumor-related genes (p15, p16, E-cadherin, GST-pi, hMLH1, and VHL) by methylation-specific polymerase chain reaction. Nontumorous gastric tissues from 10 gastritis patients were used as controls. RESULTS: Hypermethylation was not detected in any tissue taken from gastritis patients but was identified in all 5 cell lines and in 24 (92.3%) gastric carcinoma patients. CpG-island methylation in tumor-related genes also was detected in 7 out of the 25 adjacent normal tissues from cancer patients. Hypermethylation of E-cadherin, p15, and p16 were detected more frequently than GST-pi and hMLH1, whereas aberrant methylation of VHL was not detected. Concurrent hypermethylation in 2 or more tumor-related genes was detected in 3 out of the 5 gastric carcinoma cell lines, 22 (84.6%) tumor samples, and 5 (20%) adjacent gastric tissues. Eighteen (69.2%) tumor samples showed hypermethylation in >or= 3 genes. CONCLUSIONS: The current study showed that concurrent hypermethylation of multiple tumor-related genes is detected frequently in gastric carcinoma and adjacent normal tissues. Study findings suggested that a mechanism that leads to dysregulation in CpG-island methylation is likely to be involved in the early gastric carcinogenesis process.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Early clinical outcomes after subfascial endoscopic perforator surgery (SEPS) and saphenous vein surgery in chronic venous insufficiency.

BACKGROUND: Subfascial endoscopic perforator surgery (SEPS) has recently become popular as a minimally invasive way to treat chronic venous insufficiency (CVI) of the lower extremities. We report the early clinical outcomes of SEPS and saphenous vein surgery in a prospective series of Chinese patients who presented with severe CVI. METHODS: All patients referred to our hospital for the management of severe CVI (class IV disease or above) after January 1998 underwent SEPS using an ultrasonic scalpel in conjunction with saphenous vein surgery. All patients were followed up prospectively to assess ulcer healing, ulcer recurrence, and symptoms after SEPS. Clinical outcome was evaluated by the scoring system suggested by the Consensus Committee of the American Venous Forum on Chronic Venous Disease. RESULTS: Over a 24-month period, we performed 36 SEPS on 31 patients. Nineteen lower extremities (53%) had active or healing ulcers. Sapheno-femoral ligation was also performed in 33 limbs (92%). Four limbs (11%) developed superficial wound infection, and two (6%) had saphenous nerve dysesthesia. The mean clinical score and disability score decreased from 8.42 to 3.42 and 1.45 to 0.31 respectively, after a median follow-up of 14 months (range, 6-22) (p < 0.005). Eleven ulcers (58%) healed within 6 weeks after surgery. At 1-year follow-up, ulcer recurrence was found in two legs (11%). CONCLUSION: SEPS is safe and feasible. Early clinical results have shown a promising outcome in patients with severe chronic venous insufficiency.

Adult↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Adult↗
PubMed2001

T cell receptor Vbeta repertoire expression reflects gastric carcinoma progression.

Analysis of TCR beta-chain complementarity-determining region size gives an indication of the T cell immune response. We examined CD4+ and CD8+ subgroups of T cells in the peripheral blood (PBL), benign gastric mucosa, and tumor (TIL) lymphocytes of 12 patients with primary gastric carcinomas of both intestinal and diffuse types. The average number of expanded clones in each compartment, expressed by the 24 families of the TCRVbeta repertoire, was analyzed according to tumor histological type, maximal invasive depth, and lymph node metastases. Fewer clones were expressed by the PBL in the cases with lymph node metastases than in those without (CD4+ P = 0.00017, CD8+ P = 0.016). Fewer CD8+ clones were expressed by the PBL in the cases with full thickness tumor infiltration than in those involving only the mucosa and submucosa (P = 0.05). The CD8+ TIL showed significantly fewer clones in the diffuse-type carcinoma than in the intestinal type (P = 0.046).

Adenocarcinoma↗
PubMed2001

Decreased type IV collagenase activity in experimental pancreatic fibrosis.

BACKGROUND: Severe hyperstimulation and duct obstruction pancreatitis (SHOP) is characterized by pancreatic fibrosis and loss of acinar cell mass. MMP-2 and MMP-9 are type IV collagenases and gelatinases. We hypothesized that fibrosis results from disruption of the normal collagen homeostasis and that altered activity of the type IV collagenases may contribute to pancreatic fibrosis in SHOP. METHODS: SHOP rats (n = 15) were prepared with pancreatic duct obstruction and cerulein (50 microg/kg/d, ip) hyperstimulation. Pancreas from unoperated control (n = 8), 48 h SHOP (n = 8), and 96 h SHOP (n = 7) rats was harvested, homogenized, and assayed for protein concentration (BCA method). Type IV collagenase (MMP-2 and MMP-9) expression was measured by zymography using gelatin as substrate. Type IV collagenase activity was quantified with a fluorescence assay. RESULTS: Expression of the active form of MMP-9 decreased while latent MMP-9 and active and latent MMP-2 increased on gelatin zymography. Activity of type IV collagenases (MMP-2 and MMP-9) progressively decreases with SHOP injury. The differences between expression and activity are likely due to posttranslational regulators such as MT-MMPs and TIMPs. CONCLUSIONS: Collagenase expression and activity are decreased in the SHOP model of pancreatitis, suggesting a decrease in the homeostatic mechanisms for type IV collagen in the extracellular matrix. Therefore, early fibrosis in the SHOP model is, at least in part, due to alterations in collagen homeostasis and not simply increased collagen production.

Animals↗
PubMed2001

Subfascial endoscopic perforator vein surgery (SEPS) using the ultrasonic scalpel.

Subfascial endoscopic perforator vein surgery (SEPS) was recently introduced as a minimally invasive method to ligate incompetent perforating veins in patients with severe chronic venous insufficiency of the lower extremities. Herein we describe a technique in which we used a 5-mm ultrasonic scalpel for the transection of perforating veins in 16 SEPS performed in 14 patients. The use of the ultrasonic scalpel allowed for the precise coagulation and transection of the perforator vein with hemostasis, while avoiding the use of metal clips. Our initial results showed that the technique was feasible with minimal morbidity. We recommend the use of the ultrasonic scalpel as an alternative tool to transect perforating veins in SEPS.

Adult↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Cyclin D2↗
PubMed2001

Gastric choriocarcinoma shows characteristics of adenocarcinoma and gestational choriocarcinoma: a comparative genomic hybridization and fluorescence in situ hybridization study.

The authors report two cases of the rare primary gastric choriocarcinoma. These tumors showed an overwhelming predominance of cytotrophoblast- and syncytiotrophoblast-like tumor cells that were positive for beta-human chorionic gonadotrophin, with small foci of glandular differentiation. Beta-human chorionic gonadotrophin was also detected serologically in one patient. Comparative genomic hybridization study was performed on one specimen. Copy number gains of chromosomes 12, 17, 20, 22, and X, together with losses on 18q, were the major findings. Except for the gain of chromosome 12, which is known to be uncommon in primary gastric adenocarcinoma but frequently associated with choriocarcinoma, the remaining genomic imbalances were among the most common comparative genomic hybridization findings reported in primary gastric adenocarcinoma. Fluorescence in situ hybridization on paraffin sections of both specimens confirmed the presence of polysomy 17 and trisomy 12. These results suggest that primary gastric choriocarcinoma genetically possesses characteristics of both adenocarcinoma and gestational choriocarcinoma. The authors believe this is the first interphase cytogenetics study on this rare tumor, and that the results support the theory that gastric choriocarcinoma arises from alternate differentiation pathways of adenocarcinoma.

Adenocarcinoma↗
PubMed2001

Chromosome 11 copy number gains and Epstein-Barr virus-associated malignancies.

Epstein-Barr virus (EBV) genome can be found in many malignant tumors in China. Previous data of interphase cytogenetics, by comparative genomic hybridization and/or fluorescence in situ hybridization, on nasopharyngeal carcinomas and natural killer cell-type non-Hodgkin lymphomas in Hong Kong have noted gains in chromosome 11. This study compares the frequency of chromosome 11 copy number gains in three different types of EBV-associated tumors in Hong Kong. Using alpha-satellite probes, the authors studied by fluorescence in situ hybridization 31 EBV-positive tumors comprising 10 EBV-positive gastric carcinomas, 8 lung lymphoepithelioma-like carcinomas, and 13 non-Hodgkin lymphomas. Trisomy or polysomy 11 was detected in 10 of 10 (100%) EBV-positive gastric carcinomas, 6 of 8 (75%) lung lymphoepithelioma-like carcinomas, and 4 of 13 (30.8%) non-Hodgkin lymphomas. Compared with the EBV-positive gastric carcinomas, the 10 EBV-negative gastric carcinomas that were also studied showed chromosome 11 copy number gains in 3 of 10 (30%), a significantly lower frequency. The authors conclude that gains in chromosome 11 are common in EBV-associated malignancies in Hong Kong, with the strongest association found in gastric carcinoma. There seems to be differences between EBV-associated tumors of different locations, and between gastric carcinomas with and without EBV.

Adult↗
PubMed2001

Protein-protein interaction of FHL3 with FHL2 and visualization of their interaction by green fluorescent proteins (GFP) two-fusion fluorescence resonance energy transfer (FRET).

LIM domain proteins are found to be important regulators in cell growth, cell fate determination, cell differentiation and remodeling of the cell cytoskeleton. Human Four-and-a-half LIM-only protein 3 (FHL3) is a type of LIM-only protein that contains four tandemly repeated LIM motifs with an N-terminal single zinc finger (half LIM motif). FHL3 expresses predominantly in human skeletal muscle. In this report, FHL3 was shown to be a novel interacting partner of FHL2 using the yeast two-hybrid assay. Furthermore, site-directed mutagenesis of FHL3 indicated that the LIM2 of FHL3 is the essential LIM domain for interaction with FHL2. Green fluorescent protein (GFP) was used to tag FHL3 in order to study its distribution during myogenesis. Our result shows that FHL3 was localized in the focal adhesions and nucleus of the cells. FHL3 mainly stayed in the focal adhesion during myogenesis. Moreover, using site-directed mutagenesis, the LIM1 of FHL3 was identified as an essential LIM domain for its subcellular localization. Mutants of GFP have given rise to a novel technique, two-fusion fluorescence resonance energy transfer (FRET), in the determination of protein-protein interaction at particular subcellular locations of eukaryotic cells. To determine whether FHL2 and FHL3 can interact with one another and to locate the site of this interaction in a single intact mammalian cell, we fused FHL2 and FHL3 to different mutants of GFP and studied their interactions using FRET. BFP/GFP fusion constructs were cotransfected into muscle myoblast C2C12 to verify the colocalization and subcellular localization of FRET. We found that FHL2 and FHL3 were colocalized in the mitochondria of the C2C12 cells and FRET was observed by using an epi-fluorescent microscope equipped with an FRET specific filter set.

Base Sequence↗
PubMed2001

Circulating Epstein-Barr virus DNA in the serum of patients with gastric carcinoma.

PURPOSE: We investigated the detectability of EBV DNA in the serum of gastric carcinoma patients in Hong Kong. Previous data have shown that approximately 10% of gastric carcinomas in Hong Kong are associated with EBV. EXPERIMENTAL DESIGN: We recruited 51 patients with gastric carcinoma, 30 patients with gastritis, and 197 apparently healthy controls. For gastric carcinoma patients, blood samples were obtained before surgery. After surgery, the resected tumor samples from the cancer cases were subjected to in situ hybridization for small EBV-encoded RNA (EBER). Serum EBV DNA in all cases was measured by real-time quantitative PCR. RESULTS: Serum EBV DNA was detectable in 5 of 5 (100%) EBER-positive gastric carcinoma cases (median concentration, 1063 copies/ml), in 13 of 14 (93%) EBER-negative gastric carcinoma cases with EBER-positive infiltrating lymphocytes (median concentration, 50 copies/ml), and in 0 of 32 (0%) EBER-negative cases. In the nontumor controls, serum EBV DNA was detectable in 7 of 30 (23%) gastritis cases (median concentration, 0 copies/ml) and in 7 of 197 (3.6%) apparently healthy individuals (median concentration, 0 copy/ml). CONCLUSIONS: Our data indicate that serum EBV DNA reflects tumoral EBER status and opens up the possibility that circulating EBV DNA may be used as a tumor marker for the EBER-positive gastric carcinomas. The biological and clinical significance of the presence of low levels of circulating EBV DNA in the minority of gastritis patients and healthy individuals remains to be elucidated.

DNA, Viral↗
PubMed2000

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.

Aged↗