PubMed Health⌕ Search

Biomedical subjects

K W Choi

Publications and source records attributed to K W Choi.

At least 19 recordsLinked to original sources
PubMed2006

Cryptococcosis in apparently immunocompetent patients.

BACKGROUND: Few reports have described the clinical and microbiological features of cryptococcosis in immunocompetent patients. AIM: To compare clinical presentations and outcomes of cryptococcosis in immunocompetent vs. immunocompromised patients. DESIGN: Retrospective case series. METHODS: All culture- or histology-confirmed cases (n = 46) of cryptococcosis in two acute hospitals in Hong Kong (1995-2005) were included. Clinical presentations, rates of fungaemia, cerebrospinal fluid (CSF) parameters and clinical outcomes were recorded. RESULTS: Twenty patients (43.5%) were apparently immunocompetent, 17 (37.0%) had predisposing factors other than HIV infection, and 9 (19.6%) were HIV-positive. Thirty-one (67.4%) presented with meningitis, four (8.7%) with pulmonary cryptococcosis, and 11 (23.9%) with extraneural, extrapulmonary cryptococcosis. Of the immunocompetent patients with retrievable isolates (n = 8), three (37.5%) were Cryptococcus gattii; all isolates (n = 6) from immunocompromised patients were Cryptococcus neoformans var. grubii. Immunocompetent patients more commonly presented with meningitis (80.0% vs. 47.1%, p = 0.03), and tended toward lower rates of fungaemia (10.0% vs. 35.3%, p = 0.06) and mortality (25.0% vs. 52.9%, p = 0.06). Death was associated with fungaemia (p = 0.01) and underlying malignancy (p < 0.01). In cryptococcal meningitis, immunocompetent patients had longer mean time from illness onset to presentation (34.4 vs. 12.6 days, p = 0.02), more intense inflammatory responses (CSF: white blood cells 108 vs. 35 x 10(9)/l, p = 0.03; protein 1.61 g/l vs. 0.79 g/l, p = 0.07), less fungaemia (0% vs. 26.7%, p = 0.04) and more satisfactory clinical outcomes (81.3% vs. 46.7%, p = 0.04). DISCUSSION: A substantial proportion of patients with cryptococcosis are apparently immunocompetent. C. neoformans var. grubii and C. gattii are the common causes. Immunocompetent patients tend to present with localized, indolent neurological disease, with more intense inflammatory responses but better clinical outcomes.

Adult↗
PubMed2005

Absence of association between angiotensin converting enzyme polymorphism and development of adult respiratory distress syndrome in patients with severe acute respiratory syndrome: a case control study.

BACKGROUND: It has been postulated that genetic predisposition may influence the susceptibility to SARS-coronavirus infection and disease outcomes. A recent study has suggested that the deletion allele (D allele) of the angiotensin converting enzyme (ACE) gene is associated with hypoxemia in SARS patients. Moreover, the ACE D allele has been shown to be more prevalent in patients suffering from adult respiratory distress syndrome (ARDS) in a previous study. Thus, we have investigated the association between ACE insertion/deletion (I/D) polymorphism and the progression to ARDS or requirement of intensive care in SARS patients. METHOD: One hundred and forty genetically unrelated Chinese SARS patients and 326 healthy volunteers were recruited. The ACE I/D genotypes were determined by polymerase chain reaction and agarose gel electrophoresis. RESULTS: There is no significant difference in the genotypic distributions and the allelic frequencies of the ACE I/D polymorphism between the SARS patients and the healthy control subjects. Moreover, there is also no evidence that ACE I/D polymorphism is associated with the progression to ARDS or the requirement of intensive care in the SARS patients. In multivariate logistic analysis, age is the only factor associated with the development of ARDS while age and male sex are independent factors associated with the requirement of intensive care. CONCLUSION: The ACE I/D polymorphism is not directly related to increased susceptibility to SARS-coronavirus infection and is not associated with poor outcomes after SARS-coronavirus infection.

Adult↗
PubMed2003

Environmental management of marine fish culture in Hong Kong.

Marine fish farming is an important commercial practice in Hong Kong. Marine fish farms located in eutrophic coastal waters often face the threat of severe dissolved oxygen depletion associated with algal blooms and red tides. On the other hand, mariculture activities also contribute to pollution. The sustainable management of mariculture requires proper siting of the fish farms and stocking density control. Both of these are related to the carrying capacity of the water body concerned, which is mainly governed by its flushing characteristics. A simple method to determine the carrying capacity of a fish farm has been developed by using three-dimensional (3D) hydrodynamic modelling and its effective coupling with a diagenetic water quality model. A systematic methodology using numerical tracer experiments has been developed to compute the tidal flushing in a fish farm. The flushing time is determined from the results of a numerical tracer experiment using robust 3D hydrodynamic and mass transport models. A unit tracer concentration is initially prescribed inside the region of interest and zero elsewhere; the subsequent mass transport and the mass removal process are then tracked. The fish farms are usually situated in well-sheltered shallow embayments and may not connect directly to the open water. It is found that it is necessary to define both "local" and "system-wide" flushing times to represent the effectiveness of the mass exchange with the surrounding water body and the open sea respectively. A diagenetic water quality model simulating the sediment-water-pollutant interaction is employed to address the response of the water column and the benthic layer to pollution discharges. With the flushing rate reliably computed, the carrying capacity of the fish farm can be determined in terms of key water quality parameters: chlorophyll-a, dissolved oxygen, organic nitrogen and potential lowest dissolved oxygen level on a day of negligible photosynthetic production. The predictions are well-supported by field data.

Aquaculture↗
PubMed2002

Increased risk of peristomal wound infection after percutaneous endoscopic gastrostomy in patients with diabetes mellitus.

BACKGROUND: Results of prospective studies on the effect of prophylactic antibiotics before percutaneous endoscopic gastrostomy are conflicting. Factors for increased risk of peristomal wound infection have not been clearly identified. AIM: To evaluate the incidence of complications of percutaneous endoscopic gastrostomy and to determine the predictors of wound infection. PATIENTS AND METHODS: Percutaneous endoscopic gastrostomy was performed on 134 patients in different disease groups between January 1996 and June 2000. Medical records were carefully reviewed for demographic data, indications for percutaneous endoscopic gastrostomy, use of prophylactic antibiotics, complications and comorbid conditions predisposing to wound infection. RESULTS: Of 134 patients, 22 (16.4%) developed complications after percutaneous endoscopic gastrostomy Wound infection, the most common complication, occurred in 19 patients (14.2%) and Pseudomonas aeruginosa was the most frequently isolated microorganism. In univariate analysis, non-malignant disease and diabetes mellitus were significantly associated with peristomal wound infection after percutaneous endoscopic gastrostomy. In multivariate analysis, only diabetes mellitus was an independent risk factor for the development of peristomal wound infection after percutaneous endoscopic gastrostomy (p = 0.035) CONCLUSIONS: Patients with diabetes mellitus have a higher risk of peristomal wound infection after percutaneous endoscopic gastrostomy.

Diabetes Complications↗
PubMed2002

Effect of rebamipide in treatment of Helicobacter pylori-associated duodenal ulcer: attenuation of chemokine expression and nitrosative damage.

Production of cytokines along with increased activity of nitric oxide synthase has been implicated as one of the contributing mechanisms of Helicobacter pylori-mediated gastroduodenal diseases. We aimed to evaluate the effect of rebamipide in treating Helicobacter pylori-associated duodenal ulcers in terms of cytokine production and nitrosative damage of the gastric mucosa. In patients with duodenal ulcers, rebamipide or placebo were given randomly after eradication. Mucosal cytokine production was measured by enzyme linked immunoassay, and nitrotyrosine immunoexpression was measured by immunohistochemistry. The inflammatory activity and degree of neutrophil infiltration were graded accordingly. The mucosal production of RANTES, interleukin-8, and TNF-alpha showed a significant decrease after eradication in patients with rebamipide after-treatment. The nitrotyrosine immunoreactivity of gastric epithelium was significantly decreased in the rebamipide group. Rebamipide treatment after eradication resulted in a significant reduction in chemokine production along with nitrotyrosine immunoexpression in Helicobacter pylori-associated duodenal ulcers.

Adult↗
PubMed2002

Efficacy of low-dose clarithromycin triple therapy and tinidazole-containing triple therapy for Helicobacter pylori eradication.

BACKGROUND: Proton pump inhibitor-based triple therapies are recommended as the first-line treatment for Helicobacter pylori eradication. AIM: To evaluate the efficacies of low-dose clarithromycin triple therapy and tinidazole-containing triple therapy in a metronidazole resistance prevalent area and to compare the efficacies with standard triple therapy. METHODS: In a randomized, multicentre, prospective study, a total of 352 patients with duodenal ulcer or non-ulcer dyspepsia were randomly divided into three groups according to the administered regimen: OAC250 group (omeprazole, 20 mg, amoxicillin, 1000 mg, and clarithromycin, 250 mg), OAC500 group (omeprazole, 20 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg) and OTC group (omeprazole, 20 mg, tinidazole, 500 mg, and clarithromycin, 500 mg). The three groups received each regimen twice daily for 7 days. Upper gastrointestinal endoscopy was performed before and 4 weeks after treatment. H. pylori status was determined by rapid urease test and 13C urea breath test. RESULTS: The eradication rates in the OAC250, OAC500 and OTC groups were 76.2%, 65.7% and 64.8% (95% confidence interval: 67.9-84.4%, 56.7-74.8% and 55.7-73.9%), respectively, by intention-to-treat analysis (P=0.149) and 92.8%, 87.2% and 84.1% (95% confidence interval: 84.4-97.3%, 77.9-93.8% and 73.9-91.2%), respectively, by per protocol analysis (P=0.088). All regimens were well tolerated and compliance was excellent. CONCLUSIONS: Both low-dose clarithromycin triple therapy and tinidazole-containing triple therapy are effective and safe regimens for H. pylori eradication.

Adult↗
PubMed2002

Long-term stress and Helicobacter pylori infection independently induce gastric mucosal lesions in C57BL/6 mice.

BACKGROUND: Long-term psychological stresses may have a role in the pathogenesis of peptic ulcer. However, the interaction between stress and Helicobacter pylori infection in the development of peptic ulcer is not established. The aim of this study was to elucidate the roles of long-term stress and H. pylori infection in the development of gastric mucosal lesions in mice. METHODS: The Sydney strain (SS1) of H. pylori was inoculated into the stomach of C57BL/J6 mice. Twelve weeks later, mice with or without H. pylori infection were exposed to long-term repeated water-immersion-restraint stress (WIRS) for 12 h per day, 3 times per week, for 8 weeks. Gastric mucosal lesions were evaluated both macroscopically (ulcer index) and microscopically (Updated Sydney System). RESULTS: The long-term WIRS induced mild inflammation, oedema, interstitial haemorrhage and superficial erosions in the stomach of mice both with and without H. pylori infection. The degree of mucosal inflammation or atrophy in H. pylori-infected mice was not influenced by the stress. In the mice without H. pylori infection, the ulcer index of the stressed mice was greater than that of non-stressed mice (1.66 +/- 0.39 versus 0.17 +/- 0.08, P = 0.007). In the mice with H. pylori infection, the ulcer index (mean +/- s(x)) of the stressed mice was also greater than that of non-stressed mice (2.31 +/- 0.59 versus 0.64 +/- 0.22, P = 0.027). CONCLUSIONS: The present study showed that long-term stress can induce gastric mucosal inflammation and erosions, and this effect may occur independently of H. pylori infection.

Animals↗
PubMed2001

Seroepidemiological study of Helicobacter pylori infection in asymptomatic people in South Korea.

BACKGROUND: Helicobacter pylori infection occurs throughout the world and causes gastroduodenal diseases in all age groups. The prevalence of H. pylori infection varies between countries and races. The aim of this study was to evaluate the seroprevalence of H. pylori infection in asymptomatic healthy people in South Korea. METHODS: From March 1998 to October 1998, 5732 asymptomatic subjects who responded to the self-assessment questionnaires from 54 hospitals in South Korea were enrolled in this study. The serum levels of antibodies for H. pylori immunoglobulinG were measured by using an ELISA test. RESULTS: The overall seroprevalence of H. pylori infection was 46.6% and there was no statistical difference between males (47.2%) and females (45.9%). In adults, a significant difference was observed between genders. According to the geographic areas, the high prevalent provinces were Kangwon (53.4%), Cheju (52.9%) and Cholla province (50.6%); Seoul (41.9%) was the lowest prevalent area. The seroprevalence increased with age and was highest when patients were aged in their 40s (78.5%). The characteristic feature of our study was that the infection rate was steeply increased in three age groups (10-12 year olds, 16-19 year olds and those aged in their 20s). In Seoul, there was no difference in the prevalence rate among the districts studied. CONCLUSIONS: This nation-wide seroprevalence of H. pylori infection in South Korea was 46.6%, which showed the transition from a developing country to a developed country. More studies on the epidemiological factors and the route of transmission of H. pylori infection should be warranted.

Adolescent↗
PubMed2001

Inducible nitric oxide synthase expression in gastroduodenal diseases infected with Helicobacter pylori.

BACKGROUND: Nitric oxide (NO) is synthesized enzymatically from L-arginine by NO synthase, which is measured by inducible NO synthase (iNOS). Helicobacter pylori (H. pylori) infection produces a state of chronic immunostimulation in the gastric epithelium. Infection with cagA+ H. pylori has greater degree of gastric inflammation and epithelial cell damage. Therefore, we compared the levels of iNOS in patients with H. pylori infection in relation to cagA status and H. pylori-related disease. MATERIALS AND METHODS: One hundred and seven patients, including 51 patients with gastric cancer, 12 patients with gastric ulcer, 18 patients with duodenal ulcer and 26 patients with chronic gastritis, were enrolled in this study. Biopsies from the antrum and body were obtained for histologic examination, culture and reverse transcriptionase-PCR (RT-PCR) for detection of iNOS gene expression. The presence of H. pylori was confirmed by Giemsa staining or culture and the gene expression of cagA in H. pylori isolates was confirmed by PCR. RESULTS: H. pylori infection was detected in 70.1% (75/107) and cagA was detected in 84.8% (28/33). iNOS expression was detected in 49.5% (53/107) and there was no significant difference in iNOS expression according to H. pylori infection nor the cagA status in the gastroduodenal diseases. However, iNOS expression was more frequently detected in gastric cancer than the other H. pylori-related diseases (64.7% vs. 35.7%, p <.05). CONCLUSION: Although NO was thought be involved in the gastric carcinogenesis, the level of NO production was not related to H. pylori infection or cagA status.

Adult↗
PubMed2001

The clinical significance of common bile-duct dilatation in patients without biliary symptoms or causative lesions on ultrasonography.

BACKGROUND AND STUDY AIMS: Although abdominal ultrasonography (US) is a good initial screening method for detection of biliary tract disease, we sometimes encounter patients who only have findings of dilatation of the common bile duct (CBD) on US, without specific biliary symptoms or jaundice. This study aimed to evaluate the causes and clinical significance of dilatation of the CBD in patients without biliary symptoms, jaundice, or causative lesions at US. PATIENTS AND METHODS: A total of 77 patients who had no biliary symptoms and whose internal CBD diameter was more than 7 mm, without definite causative lesions on US, were enrolled. Of these, 49 underwent endoscopic retrograde cholangiopancreatography (ERCP) and 28 underwent follow-up US or computed tomography (CT) instead of ERCP. We excluded patients whose bilirubin level had increased beyond the upper normal level or who had previous history of upper abdominal surgery including cholecystectomy. RESULTS: The ERCP findings were as follows: no lesion in 20 patients (40.8%), juxtapapillary duodenal diverticulum (JDD) in 11 (22.5%), benign stricture in ten (20.4%), distal CBD mass in two (4.1%), choledochal cyst in two (4.1%), anomalous union of the pancreaticobiliary duct (AUPBD) in two (4.1%), and choledochal cyst with AUPBD in two (4.1%). There were no differences in age or in alkaline phosphatase or gamma-glutamyl transpeptidase (GGT) levels between the patients who had causative lesions revealed at ERCP and those who did not. Among the 28 patients who did not undergo ERCP, 12 had returned to normal and eight had no change in CBD diameter on follow-up US. Among eight patients who underwent CT, there were four with normal findings, one with JDD, and three with suspected choledochal cysts. CONCLUSIONS: We detected a significant number of causative biliary tract lesions in asymptomatic adults with dilatation of the CBD on routine abdominal US; no laboratory or demographic parameters were useful for discrimination. Further diagnostic study will be helpful for the early diagnosis of biliary tract disease in such patients.

Adult↗
PubMed2001

Risk factors suggesting malignant transformation of gastric adenoma: univariate and multivariate analysis.

BACKGROUND AND STUDY AIMS: Since gastric adenomas are precancerous lesions, polypectomy is necessary. However, there have been no reports suggesting factors capable of predicting malignant transformation of gastric adenomas removed by endoscopic snare polypectomy (ESP) or endoscopic mucosal resection (EMR) in Korea, a country in which gastric cancer is a major problem. The aim of this paper was to elucidate the risk factors suggesting malignant transformation of gastric adenomas removed by ESP or EMR at our center. PATIENTS AND METHODS: Between November 1994 and June 1999, 118 gastric adenomas diagnosed on the basis of endoscopy and histological examinations of the forceps biopsy specimens obtained were treated by ESP or EMR at our department. Factors capable of predicting malignancy were searched for in the endoscopy reports, still photographs, and histopathological findings. RESULTS: Eight of the 118 adenomas ultimately proved to have malignant foci. In the univariate analysis, four of the variables studied--location, histological type, surface redness, and degree of dysplasia--had a statistically significant relationship with malignant transformation. In the multivariate analysis, only the degree of dysplasia had a statistically significant relationship with malignant transformation. CONCLUSIONS: These results suggest that a diagnosis of high-grade dysplasia in forceps biopsy material should be considered an absolute indication for ESP or EMR.

Adenoma↗
PubMed2001

The analysis of resectability and survival in pancreatic cancer patients with vascular invasion.

One of the major limitations of curative resection in patients with pancreatic cancer is local tumor extension to the mesenteric vessels. Thus, the purposes of our study were to assess the clinical value of contrast-enhanced spiral computed tomography (CT) in predicting the resectability and survival of patients with pancreatic cancer with suspicious vascular invasion and to assess the influence of curative resection on the survival of these patients. We enrolled 40 patients with pancreatic cancer who were suspected of having an involvement of the adjacent large vessels and who subsequently underwent operation with curative intent in the study. Resectability and survival were correlated with CT findings such as segment length, degree of encasement, and type and number of vessels involved. The survival rate was compared between the curative and palliative resection groups, and survival rate was compared between the resected and unresected groups. Of the 40 patients with adenocarcinoma of the pancreas, 14 had curative resections and 26 had palliative resections. The probability of curative resection was higher in patients with segment lengths less than 2 cm, as compared with segment lengths more than 2 cm. However, there was no difference in survival between the two groups. There were no differences in resectability and survival according to the degree of encasement and type and number of vessels involved. There was no difference in survival between the curative and palliative resection groups. There was no difference in survival between the resected and unresected groups. A survival benefit was not achieved by curative resection in patients with pancreatic cancer with vascular invasion. Therefore, it would be better to avoid aggressive surgery in patients with pancreatic cancer with vascular invasion.

Humans↗
PubMed2001

Clinical significance of enlarged perihepatic lymph nodes in chronic hepatitis B.

GOALS: To evaluate the clinical significance of enlarged perihepatic lymph nodes in patients with chronic hepatitis B. BACKGROUND: Enlargement of perihepatic lymph node is a common finding during ultrasonography in patients with chronic hepatitis. Its relation with liver histology and viremia was reported in chronic hepatitis C, but little has been known about its clinical significance in chronic hepatitis B. STUDY: We evaluated the clinical significance of perihepatic lymphadenopathy in chronic hepatitis B. In 50 patients with biopsy-proven chronic hepatitis B and 15 healthy controls, the perihepatic lymph node volume was evaluated by ultrasonography and its possible correlation with biochemical tests, hepatitis activity index, and hepatitis B viremia was investigated. RESULTS: Perihepatic lymph node was detected in 48 of 50 patients with chronic hepatitis B (volume = 3.4 +/- 2.4 mL) and in two of 15 controls (0.4 mL and 0.6 mL). In chronic hepatitis B, lymph node volume showed a significant correlation with serum aspartate transaminase (r = 0.66), alanine transaminase (r = 0.63), gamma-glutamyl-transpeptidase (r = 0.53), histologic activity index (r = 0.59), and necroinflammatory score (r = 0.59; p < 0.05 for all), but not with fibrosis score and serum hepatitis B viremia. CONCLUSIONS: Enlarged perihepatic lymph nodes in chronic hepatitis B can be a good indicator for histologic and biochemical inflammatory activity of the liver, but not for viremia.

Adolescent↗
PubMed2001

Lipiodol accumulation in focal peliosis hepatis with sinusoidal dilatation.

Peliosis hepatis is a rare benign condition that is histologically characterized by multiple cystic blood-filled spaces in the liver. Although the cause is unknown, the condition occurs in association with several diseases or medications. We report a patient who was found to have a lesion with lipiodol accumulation in the liver 2 months after its intraarterial injection. The lesion was diagnosed and treated as a small hepatocellular carcinoma. However, subsequent right hepatic lobectomy and histologic examination confirmed the diagnosis of focal peliosis hepatis.

Adult↗