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Biomedical subjects

S C Chung

Publications and source records attributed to S C Chung.

At least 19 recordsLinked to original sources
PubMed2005

Transoral obesity surgery: endoluminal gastroplasty with an endoscopic suture device.

BACKGROUND AND STUDY AIMS: Surgical creation of a small gastric pouch with a restricted outlet is a well-established option for the treatment of morbid obesity. This report describes initial experience with endoscopic transoral stomach partition using a newly designed suturing apparatus. MATERIALS AND METHODS: A fresh porcine stomach was placed in the Erlangen model. A prototype suture device, incorporating a curved needle and an intracorporeal tightening mechanism, was used in this procedure. A long fishing line was first introduced into the stomach, with the two ends left outside. The suturing device, premounted outside a standard gastroscope, was inserted into the stomach and delivered several stitches attaching the fishing line to both the anterior and posterior walls along the line for the stomach to be partitioned. Five throws of half-hitches were tied onto the fishing line extracorporeally and separately pushed into place, creating a gastric pouch just below the esophagogastric junction. A flexible sheath of 8 cm long was then put on one side of the fishing line and pushed into the stomach. Additional extracorporeal knots were tied on the fishing line, forming a restrictive ring at the outlet of the pouch. The ring was then anchored to the stomach wall with similar endosutures. RESULTS: The proximal gastric pouch, with an estimated volume of approximately 100 ml, was successfully created with a restrictive band at its outlet. All of the stitches were securely sutured, with consistent penetration of the muscular layer of the stomach wall. CONCLUSIONS: In a bench model, it is technically possible to accomplish transoral gastroplasty endoscopically with an intraluminal suturing device. Further live animal studies will be needed in order to confirm the efficacy and safety of this procedure before clinical application.

Animals↗
PubMed2005

Assessing the adequacy of endoscopically tied knots: a functional approach.

BACKGROUND AND STUDY AIMS: Endoscopic intracorporeal knots have potentially enormous applications in endoscopic surgery. We describe a method for testing the security of various types of endoscopically tied knots using a vessel perfusion manometer system. METHODS: A 4-cm segment of porcine splenic artery was placed on the mucosal surface of a pig stomach. The two ends of the vessel were brought out through the gastric wall and connected to a two-way manometer. One end was also joined to a pressure infusion bag. The stomach was mounted in an Erlangen training model. A long 3/0 nylon thread, previously introduced into the submucosal layer of the stomach and encircling the vessel, was brought out from the mouth. Three-throw square knots, Mayo knots, "surgeon's" knots and five-throw square knots were tied and pushed into place using a cap attached to a gastroscope. The pressure at the two ends of the artery was compared. If the pressure could be increased to over 200 mm Hg at one end without a change in the other, the knot was considered secure. RESULTS: Each type of knot was tested 12 times under endoscopic vision. The range for mean knotting time was 3.4 - 4.5 minutes. Five-throw knots took significantly longer to tie than three-throw knots (P < 0.005). There was one loose knot in each of the three-throw and Mayo groups, and three each in the "surgeon's" and five-throw groups (P > 0.05). CONCLUSIONS: This system is a reliable model for testing intracorporeal knots tied endoscopically. A three-half-hitches square knot with 3/0 nylon, tied using a flexible endoscope and knot-tightening cap, can withstand pressure up to 200 mm Hg.

Animals↗
PubMed2003

Synthesis of Si, Mg substituted hydroxyapatites and their sintering behaviors.

Si, Mg-substituted hydroxyapatites, alone and co-substituted, have been prepared to obtain biomaterials having an improved biocompatibility. From FT-IR, XRD and ICP analyses, it was confirmed that single phases of hydroxyapatite substituted by Si alone or co-substituted by Si, Mg. The XRD data indicated the absence of extra phases related to silicon and magnesium oxide or other calcium phosphate species. Si-substituted hydroxyapatite of up to 2 wt% for Si and Si, Mg co-substituted hydroxyapatite of 1 wt% for the each ion keep their original structures intact for the sintering temperatures of up to 1200 degrees C. However, it is observed that ion substitutions by an amount higher than the above ratios for each hydroxyapatite lead to destabilization of original structures of the hydroxyapatite and to the production of tricalcium phosphate and calcium phosphate silicate phases when the samples were sintered at 1100 degrees C or higher.

Biocompatible Materials↗
PubMed2003

[Severe acute respiratory syndrome (SARS)].

The severe acute respiratory syndrome (SARS) is a highly infectious respiratory disease, to the best of our knowledge caused by a hitherto unknown corona virus. The virus has spread from South East Asia to many countries of the world. Three case reports of patients from the Prince of Wales Hospital of The Chinese University of Hong Kong demonstrate typical clinical courses. Fever, cough, in most cases non-productive, myalgia, chills, and rigor are the leading symptoms. Leucopenia and thrombocytopenia are the most prominent laboratory parameters, increased values for lactatedehydrogenase (LDH) reflect a more severe clinical course. Advanced age and coexisting conditions seem to influence the prognosis unfavourably. The chest roentgenogram may be normal initially but at a later stage progressive consolidations in the majority of peripheral parts of the lung are observed, which cannot be differentiated from pneumonias of other origin. Even young patients can enter a stage of respiratory compromise rather fast. A therapy against the cause of the disease is not known. Empirical therapy with ribavirin in combination with high dose corticosteroids have proved successful. The disease may progress into respiratory failure comparable with an acute respiratory distress syndrome (ARDS). Mortality is around five to ten per cent. Stringent hygiene and quarantine measures are mandatory to prevent the further spread of this threatening disease.

Adult↗
PubMed2002

Detection of ABH blood group antigens in the saliva of Koreans and their stability according to storage of saliva samples.

The purpose of the present study was to identify salivary molecules carrying the ABH blood group antigens in Koreans and to investigate the changes in these antigens according to processing and storage of saliva samples. Secretor or non-secretor phenotypes and salivary components carrying the ABH antigens were identified in 90 subjects, 30 subjects in each ABO blood group, by SDS-PAGE and immunoblotting. Saliva samples were then obtained from 12 secretors-two males and two females in each ABO blood group and aliquots of both fresh saliva samples and their supernatants after centrifugation were stored at room temperature, 4, -20 and -70 degrees C. The same experiments were performed after 1, 3 and 6 months to investigate changes in the blood group antigens. In all 68 secretors, high-molecular-weight salivary mucin (MG1) was found to be the primary carrier of the ABH antigens. A salivary component of approximately 80 kDa also carried H antigen in seven saliva samples of 22 blood type O secretors. The blood group antigens were better detected in centrifuged samples. In saliva samples preserved at room temperature and 4 degrees C, the blood group antigens were either not detected or detected as degraded molecules. No change was found in the blood group antigens in saliva samples preserved at -20 and -70 degrees C for 6 months.

ABO Blood-Group System↗
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

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.

Anti-Bacterial Agents↗
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

Delivery and scavenging system for small animal inhalational anesthesia.

BACKGROUND: Inhalational agents have been widely used for anesthesia in laboratory animals. However, the safe use of inhalational agents in small laboratory animals has been limited by the lack of a suitable and effective scavenging system for the removal of waste anesthetic gases. The aim of the present study is to develop an anesthetic system that can be manufactured using common household and laboratory items. MATERIALS AND METHODS: An anesthetic system was designed for rats weighing from 300 to 350 g. A face mask for the rat was made by cutting off the distal part of a 50-ml centrifuge tube. A scavenging hood was made from a transparent plastic food storage box. Exhaust of anesthetic gases from the scavenger hood was facilitated by fitting an outlet connected to a pump. Four experienced researchers or technicians tested the scavenger hood. RESULTS: In 79.2% of the trials the participants could smell halothane when the pump from the scavenger system was not operational. However, when the pump was switched on, halothane was detected only 16.7% of the time (P < 0.001). CONCLUSION: We have developed a simple and effective method of delivering inhalational anesthesia to small laboratory animals and of removing waste anesthetic gases.

Anesthesia, Inhalation↗
PubMed2001

An improved rat model of obstructive jaundice and its reversal by internal and external drainage.

BACKGROUND: A simple and reproducible rat model that allows studies of the reversal of obstructive jaundice (OJ) by internal (ID) and external (ED) drainage is not available at present. METHODS: OJ was induced in rats by double ligation and division of the common bile duct. To minimize tissue handling and dissection the duodenum was extracted with a ophthalmic muscle hook and the common bile duct isolated using very fine forceps. One week after bile duct ligation, ID was accomplished by implanting a length of infant feeding tube between the dilated bile duct and the duodenum. ED was achieved by placing a PVC tube into the dilated bile duct and exteriorizing the other end at the nape of the neck. RESULTS: Minimal adhesions were found around the dilated common bile duct, which made relaparotomy for drainage easy. Alanine transaminase, total bilirubin, alkaline phosphatase, and gamma-glutamyltransferase were significantly raised after bile duct ligation. All parameters returned to control levels after ID for 7 days. In the ED group plasma albumin was significantly decreased and alkaline phosphatase remained marginally elevated. CONCLUSIONS: We have developed a simple and reproducible rat model that allows for the study of reversal of OJ by ID or ED. We also demonstrated that ID is superior to ED in reversing impaired liver function in OJ.

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

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.

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↗