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H K Choi

Publications and source records attributed to H K Choi.

At least 19 recordsLinked to original sources
PubMed2006

Differential expression of manganese superoxide dismutase, copper/zinc superoxide dismutase, and catalase in gastric adenocarcinoma and normal gastric mucosa.

AIMS: The biologic significance of antioxidant enzymes (AOEs) in gastric adenocarcinoma is still unclear. The aims of this study was to investigate the differential expression of AOEs in gastric carcinoma cells and non-cancerous counterparts and the relationship with the various clinicopathologic variables in gastric cancer patients. METHODS: Expression status of MnSOD, Cu/ZnSOD, and catalase was evaluated immunohistochemically in 120 paired gastric cancer and adjacent non-cancerous tissue. The tissues were fixed in absolute methanol immediately after surgical resection and immunohistochemistry was performed by microprobe system using tissuemicroarray slides. RESULTS: All AOEs revealed moderate to strong immunoreactivity in the parietal and intestinal metaplastic cells. Stromal cells in both cancer and non-cancerous tissue expressed MnSOD and catalase but Cu/ZnSOD. Immunoreactivity of MnSOD and catalase was increased in gastric carcinoma cells compared to their non-cancerous counterparts and revealed an association with intestinal type adenocarcinomas whereas immunoreactivity of Cu/ZnSOD did not reveal significant difference between cancer and non-cancerous mucosal cells. CONCLUSIONS: Expression of MnSOD, Cu/ZnSOD, catalas in gastric cancer cells and non-cancerous counterparts was different and increased MnSOD and possibly catalase may in part be responsible for the increased risk of intestinal type adenocarcinoma of the stomach.

Adenocarcinoma↗
PubMed2006

Progression of radiographic joint damage in different eras: trends towards milder disease in rheumatoid arthritis are attributable to improved treatment.

BACKGROUND: Severity of rheumatoid arthritis and progression of radiographic joint damage have decreased over the last decades. AIM: To examine whether this trend is attributable to an underlying trend towards milder disease or to improved treatment. METHODS: The study used an inception cohort of patients with early rheumatoid arthritis seen at the Wichita Arthritis Center, Wichita, Kansas, USA, since 1973 and monitored prospectively since their first clinic visit through clinical, radiographic, laboratory, demographic and self-reported data. The radiographic disease progression in patients with disease onset in the 1970s, 1980s and 1990s was compared using a multivariate regression model for longitudinal data. The analysis was adjusted for differences in baseline predictors, type of disease-modifying antirheumatic drugs (DMARDs) and steroid use. RESULTS: 418 patients with rheumatoid arthritis with radiographic follow-up were included. Patients in earlier decades used fewer DMARDs, had longer disease durations and higher tender joint counts at their first visit. Other important predictors of disease progression did not differ significantly between decades of disease onset. The unadjusted rates of radiographic progression differed between decades (analysis of variance, p = 0.01), with a significant trend towards less radiographic progression in more recent times (trend, p<0.001). However, after adjusting for DMARD use, steroid use and baseline predictors, differences between decades vanished (analysis of variance, p = 0.40) and the trend towards less radiographic progression disappeared (trend, p = 0.45). CONCLUSION: These results suggest that the observed trend towards milder disease in rheumatoid arthritis is attributable to more effective antirheumatic treatment and not to a secular trend.

Adult↗
PubMed2005

Multinucleation of koilocytes is in fact multilobation and is related to aberration of the G2 checkpoint.

AIMS: To clarify the fine structure of koilocytes and correlate this with genetic aberration of the G2 checkpoint. METHODS: Three dimensional reconstruction from confocal fluorescent images, together with functional assays for key molecules of the G2 checkpoint-cdc2 and cyclin B1-was performed in human uterine cervical samples. After confirming 22 human papillomavirus (HPV) types using a DNA chip from 30 cervical swabs, previously confirmed as 15 cervical low grade and 15 high grade intraepithelial lesions, the activity of molecules involved in the G2 checkpoint was evaluated using western blotting for cyclin B1, cdc2, and phospho-cdc2 (Y15 and T161), a nuclear extraction fractional assay, and a reverse transcription polymerase chain reaction assay. In addition, three dimensional confocal image restoration was performed on confirmed cervical intraepithelial neoplasia tissue samples. RESULTS: T161 phospho-cdc2 and cyclin B1 expression was higher in HPV infected cervical lesions than in normal samples. Immunofluorescence, revealed that cyclin B1 was present predominantly in the nuclei of HPV infected cells, confirming the results of the nuclear fractional assay. On restoration of three dimensional confocal images, the multinucleation of koilocytes was revealed to be multilobation of a single nucleus, rather than true multinucleation. This multilobation appeared to be associated with chromosomal instability and aberration of the G2 checkpoint. CONCLUSIONS: The multiple nuclei of koilocytes are in fact multilobation of a single nucleus, and this phenomenon is associated with upregulation of gene products related to the G2 checkpoint.

Blotting, Western↗
PubMed2003

Comparison of stenting with emergency surgery as palliative treatment for obstructing primary left-sided colorectal cancer.

BACKGROUND: Self-expanding metallic stents provide an alternative to surgery as definitive palliation in patients with obstructing colorectal cancer. This study aimed to compare the outcome of patients with obstruction due to primary left-sided colorectal cancer treated by palliative stenting with outcome in patients who had undergone surgery. METHODS: Patients with incurable obstructing primary colorectal cancer distal to the splenic flexure treated with emergency surgery (n = 31) or placement of a metallic stent (n = 30) from November 1997 to June 2002 were included. Data on the mortality, morbidity, necessity of intensive care and hospital stay for the two groups were compared. The subsequent outcomes, including the incidence of stoma creation and survival, were also analysed. RESULTS: The two groups were similar in terms of age, sex distribution and presence of co-morbidity. Insertion of metallic stents was successful in 29 of 30 patients. Hospital death occurred in four and eight patients in the study and control groups respectively (P = 0.335). Fewer patients with placement of a stent required intensive care (1 versus 11; P = 0.001) and the median hospital stay was shorter in patients with stenting (4 versus 8 days; P = 0.008). A stoma was subsequently created in four patients with stenting, whereas 15 patients who had emergency operation required a stoma (P = 0.005). The difference in median survival between the two groups was not statistically significant (107 versus 119 days; P = 0.088). CONCLUSION: Self-expanding metallic stents are effective in the palliation of obstructing colorectal cancer. Placement of stents is associated with a shorter hospital stay, less likelihood of intensive care and a lower incidence of stoma creation, when compared with emergency surgery. Thus insertion of a metallic stent should be considered in patients with incurable obstructing colorectal cancer.

Adult↗
PubMed2003

A double-blind, randomised- placebo, controlled, parallel group, multicentre, flexible-dose escalation study to assess the efficacy and safety of sildenafil administered as required to male outpatients with erectile dysfunction in Korea.

The efficacy and safety of sildenafil was evaluated in a randomiSed, double-blind, placebo-controlled, flexible-dose study in Korean men aged 28-78 y with erectile dysfunction (ED) of broad-spectrum aetiology and more than 6 months duration. A total of 133 patients were randomised at six centres in Korea to receive either sildenafil (50 mg initially, increased if necessary to l00 mg or decreased to 25 mg depending on efficacy and tolerance) (n=66) or matching placebo (n=67) taken on an 'as needed' basis l h prior to anticipated sexual activity for a period of 8 weeks. At the end of this time, the primary efficacy variables relating to the achievement and maintenance of erections sufficient for sexual intercourse, and the secondary efficacy variables, which included: (1) the five separate domains of sexual functioning of the International Index of Erectile Function (IIEF) scale, (2) the percentage of successful intercourse attempts, and (3) a global assessment of erections, were all statistically significantly improved by sildenafil in comparison with placebo (P&<0.0001). Treatment-related adverse events occurred in 56.1% of patients receiving sildenafil and 20.9% receiving placebo. The most common adverse events with sildenafil were vasodilatation (flushing), headache and abnormalities in colour vision (31.8, 22.7 and 6.1% of patients, respectively), and most were mild in nature. The efficacy and safety of sildenafil in this population of Korean men appears similar to that reported in other studies in western populations.

Adult↗
PubMed2003

Reactivity of sera from cases of Plasmodium vivax malaria towards three recombinant antigens based on the surface proteins of the parasite.

Sera collected in South Korea, from 61 cases of Plasmodium vivax malaria and, as controls, 40 healthy volunteers, were tested in ELISA for IgG or IgM reacting with any of three recombinant P. vivax proteins. The antigens used, representing the parasite's major merozoite surface protein (MSP), circumsporozoite surface protein (CSP) and Duffy-binding protein (DBP), had all been expressed in an Escherichia coli system and purified. The ELISA results were recorded as optical densities (OD). The highest ratio observed between the mean OD for a malaria serum and that for a control serum was that for IgG against MSP, although CSP gave a higher ratio than MSP or DBP in the IgM ELISA. In the ELISA for IgG, the OD for MSP were found to be correlated with those for DBP (r = 0.53; P < 0.5) but the OD for CSP were not correlated with those for MSP or DBP. As the most intense reactions observed were those between the IgG from the malaria sera and the recombinant MSP, the latter antigen may be useful in diagnostic tests and as a component of any vaccine used to protect against P. vivax malaria.

Adult↗
PubMed2003

The value of flexible sigmoidoscopy for patients with bright red rectal bleeding.

OBJECTIVE: To review the diagnostic yield of flexible sigmoidoscopy in patients presenting with bright red rectal bleeding. DESIGN: Retrospective study. SETTING: University teaching hospital, Hong Kong. SUBJECTS AND METHODS: Patients who underwent flexible sigmoidoscopy between January 1995 and April 1996 for investigation of bright red rectal bleeding were recruited. The extent of the endoscopic examination, complications, and endoscopic findings were recorded. RESULTS: A total of 1052 patients were included in the study. The mean length of endoscopic examination was 55 cm. There were no complications attributed to the procedure. Thirteen (1.2%) patients aged from 41 to 87 years were found to have malignant tumours that were not palpable on digital examination. All the tumours were moderately differentiated adenocarcinoma. Two patients had synchronous liver metastasis at presentation. Adenomatous polyps were detected in 81 (7.7%) patients, of whom 76 were older than 40 years. The majority of polyps were tubular adenomas associated with mild or moderate dysplasia. Other endoscopic findings included hyperplastic and juvenile polyps, proctocolitis, diverticulosis, irradiation colitis, ischaemic colitis, rectal ulcers, and infective colitis. The overall diagnostic yield was 21.1%. No mucosal lesion was detected by flexible sigmoidoscopy in 78.9% of patients in whom the rectal bleeding was due to either haemorrhoids or anal fissure. CONCLUSIONS: Cancer was detected in 1.2% and adenomatous polyps in 7.7% of patients with bright red rectal bleeding using flexible sigmoidoscopy. All cancers and 94% of adenomatous polyps were detected in patients older than 40 years. Flexible sigmoidoscopy appears to be a valuable initial investigation for bright red rectal bleeding in patients older than 40 years.

Adolescent↗
PubMed2002

Radiation stricture of rectosigmoid treated with self-expanding metallic stent.

Radiation stricture of the rectosigmoid with obstruction is a difficult clinical problem, and surgery is associated with high mortality and morbidity. We report a case involving radiation stricture of the rectosigmoid in an 80-year-old woman who presented with acute colonic obstruction. A self-expanding metallic stent was successfully inserted, and the obstruction was relieved. The stent remained patent for 4 months without any complications until the patient died of sepsis resulting from pneumonia and bedsores. The literature on the use of a metallic stent to manage a benign colon condition was reviewed.

Aged↗
PubMed2002

Effects of posttraining treatments in the posterior cingulate cortex on short- and long-term memory for inhibitory avoidance in rats.

Adult male Wistar rats were bilaterally implanted with indwelling cannulae in the caudal region of the posterior cingulate cortex. After recovery, animals were trained in a step-down inhibitory avoidance task (3.0-s, 0.4-mA foot shock) and received, right after training, a 0.5-microl infusion of vehicle (phosphate-buffered saline, pH 7.4), of the GABA(A) receptor agonist muscimol (0.1 or 0.5 microg), of the cAMP-dependent protein kinase (PKA) stimulant Sp-cAMPS (0.1 or 0.5 microg), or of the PKA inhibitor Rp-cAMPS (0.1 or 0.5 microg). Animals were tested twice, 1.5 h and, again, 24 h after training, in order to examine the effects of these agents on short- and long-term memory, respectively. Muscimol (0.5 but not 0.1 microg) hindered retention for both short- and long-term memory (p <.05). Rp-cAMPS (0.1 or 0.5 microg) hindered retention for short-term memory (p <.05). In addition, these animals showed lower, but not significantly lower, latencies than controls in the test session for long-term memory (p >.10). A trend toward an amnesic effect on long-term memory was also observed after Sp-cAMPS infusion at 0.1 microg (p <.10). These results show that strong stimulation of GABAergic synapses in the caudal region of the rat posterior cingulate cortex right after training impairs short- and long-term memory (the latter less dramatically). The same occurs by inhibiting PKA activity with regard to STM and possibly to LTM.

Animals↗
PubMed2002

Randomized clinical trial comparing loop ileostomy and loop transverse colostomy for faecal diversion following total mesorectal excision.

BACKGROUND: The aim of this study was to compare loop ileostomy and loop transverse colostomy as the preferred mode of faecal diversion following low anterior resection with total mesorectal excision for rectal cancer. METHODS: Patients who required proximal diversion after low anterior resection with total mesorectal excision were randomized to have either a loop ileostomy or a loop transverse colostomy. Postoperative morbidity, stoma-related problems and morbidity following closure were compared. RESULTS: From April 1999 to November 2000, 42 patients had a loop ileostomy and 38 had a loop transverse colostomy constructed following low anterior resection. Postoperative intestinal obstruction and prolonged ileus occurred more commonly in patients with an ileostomy (P = 0.037). There was no difference in time to resumption of diet, length of hospital stay following stoma closure and incidence of stoma-related complications after discharge from hospital. A total of seven patients had intestinal obstruction from the time of stoma creation to stoma closure (six following ileostomy and one following colostomy; P = 0.01). CONCLUSION: Intestinal obstruction and ileus are more common after loop ileostomy than loop colostomy. Loop transverse colostomy should be recommended as the preferred method of proximal faecal diversion.

Adult↗
PubMed2001

Differential expression of Vibrio vulnificus elastase gene in a growth phase-dependent manner by two different types of promoters.

Elastase activity of Vibrio vulnificus was highly dependent on growth phase, reached a maximum during the stationary phase, and was regulated at the level of transcription. The stationary phase production of elastase in crp or rpoS mutants, which were constructed by allelic exchanges, decreased about 3- and 10-fold, respectively. However, the promoter activity of vvpE encoding elastase was unaffected by those mutations in the log phase when analyzed using a vvpE-lux fusion. A primer extension analysis revealed that the transcription of vvpE begins at two different sites, consisting of putative promoter L (PL) and promoter S (PS). The PL activity was constitutive through the log and stationary phases, lower than the PS activity, and unaffected by the crp or rpoS mutations. The transcription of PS, induced only in the stationary phase, was dependent on RpoS. The mutation in crp reduced the activity of PS; however, the additional inactivation of crp did not influence the PS activity in the rpoS mutant, indicating that CRP exerted its effects through PS requiring RpoS. These results demonstrate that vvpE expression is differentially directed by PL and PS depending on the growth phase and elevated by RpoS and CRP in the stationary phase.

Alleles↗
PubMed2001

Protein-fatty acid complex for enhanced loading and stability within biodegradable nanoparticles.

Lysozyme was hydrophobically modified with a fatty acid, sodium oleate, via an ion-pairing mechanism. Ionic binding between an anionic carboxylic group of sodium oleate and basic amino groups in lysozyme was primarily utilized to form lysozyme-oleate complex. The complex formation was pH dependent. The lysozyme-oleate complex dissolved in an organic solvent exhibited much higher conformational stability at elevated temperature compared with free lysozyme in the same solvent. The complex was formulated into biodegradable nanoparticles by a spontaneous emulsion and solvent diffusion method. The resultant formulation showed near 100% encapsulation efficiency of lysozyme within nanoparticles with < 100 nm in diameter with a narrow size distribution. Lysozyme could be loaded into the nanoparticles up to 18.6% (w/w) with concomitantly increased particle sizes. This study demonstrates a new formulation method of biodegradable nanoparticles with highly efficient encapsulation of proteins, which are potentially useful for oral protein delivery including mucosal vaccination.

Biocompatible Materials↗
PubMed2001

A novel mucoadhesive polymer prepared by template polymerization of acrylic acid in the presence of chitosan.

A novel mucoadhesive polymer was prepared by template polymerization of acrylic acid in the presence of chitosan for transmucosal drug delivery system (TMD). FT-IR results indicated that polymer complex was formed between poly(acrylic acid) (PAA) and chitosan through hydrogen bonding. Glass transition temperature (Tg) of chitosan and PAA in the PAA/chitosan polymer complexes was inner-shifted compared with Tg of chitosan and PAA itself. This may be due to the increased miscibility of PAA with chitosan through the hydrogen bonding. The crystallinity of chitosan in the PAA/chitosan polymer complexes was decreased with polymer complex formation with PAA. The dissolution rate of the PAA/chitosan polymer complex was dependent on pH and ratio of PAA/chitosan. The mucoadhesive force of PAA/chitosan polymer complex was similar to a commericial product, Carbopol 971P NF.

Acrylates↗
PubMed2001

Distribution of tracheal and laryngeal mucous glands in some rodents and the rabbit.

We used scanning electron microscopy to count the number of mucous gland openings in the tracheae and lower portion of the larynges of the rat, guinea pig, hamster, mouse and rabbit. Cells of the airway surface epithelium were removed by protease digestion better to visualise the gland openings. The distribution of glands was further studied by conventional histology and by PAS/Alcian blue staining of whole mounts. In all rodent species, gland openings in the larynx occurred with a frequency of 1-2 per mm2. Mice had no gland openings in their tracheae, and hamsters, only a handful. Rat tracheae contained 126+/-42 gland openings (+/-S.D.; n = 6) at a frequency of approximately 0.6 per mm2 at the top of the trachea and approximately 0.15 per mm2 at the bottom. Guinea pig tracheae contained 153+/-90 gland openings (+/-S.D.; n = 5), with 54% being in the top 40% of the trachea. In both rat and guinea pig, tracheal glands were found in the ventral aspect between the cartilaginous rings, and were absent from the dorsal membranous portion. Gland openings in most species were simple circles of approximately 50 microm diameter. However, glands in the rat trachea generally opened obliquely into shallow (approximately 20 microm deep) oval troughs (approximately 150 x 75 microm), which had their long axes oriented from head to tail. In the rabbit, there was no evidence of tracheal or laryngeal glands histologically. However, the tracheal and laryngeal surfaces contained numerous pits (approximately 30 microm diameter) distributed evenly over and between cartilages at a frequency of approximately 4 per mm2. These may correspond to the 'nests' of goblet cells described by others.

Animals↗
PubMed2001

Autoimmune vestibulo-cochlear disorders.

Autoimmune vestibulo-cochlear disorders (AVCD) represent a group of syndromes with overlapping clinical features, manifesting as sensorineural hearing loss, often associated with vertigo, tinnitus, and aural fullness, and believed to be caused by an autoimmune mechanism. Although definitive evidence of a classic "autoimmune process" is still lacking, substantial indirect evidence has accumulated to strongly indicate such a pathogenesis. Rapidly progressing AVCD is analogous to rapidly progressive glomerulonephritis in that inner ear inflammation progresses to severe, irreversible damage within 3 months of onset (and often much more quickly). Thus patients with rapidly progressive AVCD are treated with a sense of urgency. Prompt treatment with corticosteroids and other antirheumatic/immunosuppressive agents can preserve hearing and vestibular functions. We are not aware of any randomized controlled clinical trials evaluating the efficacy of antirheumatic/immunosuppressive agents in AVCD. In this article we review reports of various therapies that have been tried in this condition and our experience of etanercept therapy in AVCD.

Antirheumatic Agents↗