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Biomedical subjects

J S Choi

Publications and source records attributed to J S Choi.

At least 91 records · Page 5Linked to original sources
PubMed1998

Renal transport systems for organic anions and cations in cadmium-exposed rats.

To evaluate the effect of cadmium intoxication on renal transport systems for organic anions and cations, transport of p-aminohippurate (PAH) and tetraethylammonium (TEA) were studied in renal cortical plasma membrane vesicles isolated from cadmium-intoxicated rats. Cadmium intoxication was induced by daily injections of CdCl2 (2 mg Cd/kg.day sc) for 2-3 weeks. Renal plasma membrane vesicles were prepared by Percoll gradient centrifugation and magnesium precipitation method. Vesicular uptake of substrate was determined by rapid filtration technique using Millipore filter. The cadmium treatment resulted in a marked attenuation of Na(+)-dependent, alpha-ketoglutarate (alpha KG)-driven PAH uptake in the basolateral membrane vesicle (BLMV), and this was due to a reduction in Vmax and not K(m). The Na(+)-alpha KG symport activity of the BLMV was not affected by 2-week cadmium treatment, but it was significantly inhibited by 3-week cadmium treatment. On the other hand, the alpha KG-PAH antiport activity of the BLMV appeared to be markedly suppressed in 2-week as well as 3-week cadmium-treated animals. The cadmium treatment inhibited the proton gradient-dependent TEA transport in the brush-border membrane vesicle (BBMV), and this was associated with a reduction in Vmax with no change in K(m). These results indicate that cadmium exposures may impair the capacities for organic anion transport in the proximal tubular basolateral membrane and organic cation transport in the luminal membrane. The cadmium effect on organic anion transport is attributed mainly to an inhibition of dicarboxylate-organic anion antiport system.

Animals↗
PubMed1998

In vitro angiogenic activity of Aloe vera gel on calf pulmonary artery endothelial (CPAE) cells.

Angiogenic activity of Aloe vera gel was investigated by in vitro assay. We obtained the most active fraction from dichloromethane extract of Aloe vera gel by partitioning between hexane and 90% aqueous methanol. The most active fraction (F3) increased the proliferation of calf pulmonary artery endothelial (CPAE) cells. In addition, F3 fraction induced CPAE cells to invade type 1 collagen gel and form capillary-like tube through in vitro angiogenesis assay, and increased the invasion of CPAE cells into matrigel through in vitro invasion assay. Furthermore, the effect on the mRNA expression of proteolytic enzymes which are key participants in the regulation of extracellular matrix degradation was investigated by northern blot analysis. F3 fraction enhanced mRNA expression of urokinase-type plasminogen activator (u-PA), matrix metalloproteinase-2 (MMP-2), and membrane-type MMP (MT-MMP) in CPAE cells whereas the expression of plasminogen activator inhibitor-1 (PAI-1) mRNA was not changed.

Aloe↗
PubMed1998

Expression of hMSH2 and hMLH1 in colorectal carcinomas with microsatellite instability.

Microsatellite instability (MIN) due to defective mismatch repair (MMR) genes has been reported in a subset of sporadic colorectal carcinomas and in the majority of tumors from patients with hereditary nonpolyposis colorectal cancer (HNPCC) syndrome. Among the known MMR genes, hMSH2 and hMLH1 genes are known to be predominantly altered in HNPCC patients and MIN-positive tumors. In this study, we examined MIN and the protein expression pattern of the hMSH2 and hMLH1 by Western blot and immunohistochemistry from 32 sporadic colorectal carcinomas. MIN was observed in 6 (18%) colorectal carcinomas. Of the 6 MIN-positive tumors, one case showed no expression of either protein, 3 cases showed an absence of hMSH2 protein expression, one case showed an absence of hMLH1 protein expression and one case showed no altered expression of either protein by immunohistochemistry. The decreased expression of the hMSH2 protein in a tumor compared to the normal mucosa was also observed in 5 of the 6 MIN-positive cases by Western blot analysis. All of the MIN-negative tumors showed expression of both proteins by immunohistochemistry. Thus most of the MIN-positive tumors appear to be directly related to the altered expression of these two genes and can be diagnosed by the examination of protein expression.

Adaptor Proteins, Signal Transducing↗
PubMed1998

NF-kappa B activation following optic nerve transection.

In order to elucidate in vivo neuronal cell death in the retina, and involvement of NF-kappa B in this process, we studied the degeneration of retinal ganglion cells (RGCs) and the activation of NF-kappa B after transection of the optic nerve of adult rat at 5 mm from the eyeball. The morphology of dying ganglion cells in the retinal ganglion cell layer was observed by light and electron microscopy, the activation of NF-kappa B was investigated immunohistochemically. Seven and 14 days post-axotomy, dying cells contained pyknotic nuclei. The death of retinal ganglion cells involved apoptosis, activation of NF-kappa B (p50 and p65) was prominent in a time dependent manner. We observed axotomy-induced NF-kappa B activation, which may mediate apoptosis of retinal ganglion cells.

Animals↗
PubMed1998

Prevalence and disease experience rates in Korean physicians.

This study aimed to find out the morbid status of Korean physicians living in Korea, as one part of a feasibility study on the Korean physician cohort. It was performed by mail survey using a self-administered questionnaire from Jan. 1, 1995 through Dec. 31, 1995. Study subjects were 21,552 including 17,877 (81.1%) males and 3,384 (15.5%) females. Person based prevalence rate of disease was 17.7% (18.3% for males and 13.8% for females) with the rate increasing with age. The disease group showing the highest prevalence rate was circulatory diseases (5.16%) for males, and respiratory disease (3.13%) for females. The individual disease showing the highest prevalence rates was hypertension (3.77%) for males and allergic rhinitis (2.25%) for females. The person based disease experience rate was 36.2% (36.9% for males, 32.7% for females) with the rate increasing with age. The disease group showing the highest disease experience rate was digestive disease for both sexes (10.05% for males, 7.42% for females). Individual disease showing the highest disease experience rate was hypertension (5.00%) for males and allergic rhinitis (4.08%) for females. There were different ranks of both prevalence and disease experience rate depending on age in both sexes.

Adult↗
PubMed1997

Purification and characterization of prophenoloxidase from the hemolymph of coleopteran insect, Holotrichia diomphalia larvae.

Prophenoloxidase (pro-PO), a precursor of phenol oxidase (PO), was purified from the hemolymph of coleopteran Holotrichia diomphalia larvae. The enzyme was purified to apparent homogeneity, in six steps of chromatography, using Sephadex G-100, CM-52, Dextran-sulfate Sepharose CL-6B, Phenyl Sepharose CL-4B, Sephacryl S-200, and a Mono-Q column. The preparation exhibited a single band on SDS-PAGE. The proenzyme had a molecular weight of 158 kDa, as estimated by gel filtration. On SDS-PAGE under reducing conditions, it gave a 79 kDa band, indicating that it forms a dimer of the 79 kDa protein. On the other hand, the purified pro-PO gave two well-separated peaks, named pro-PO-1 and pro-PO-2, on reverse-phase HPLC. Amino acid compositions of both proteins were indistinguishable, thereby suggesting the presence of an allelic variant or an isoprotein. On dextran-sulfate Sepharose CL-6B chromatography, a fraction containing prophenoloxidase activating enzyme(s) (PPAE fraction), free from pro-PO, was also separated. In reconstitution experiments, the activation of purified pro-PO by PPAE fraction, was observed in the presence of 5 mM Ca2+, with a specific limited proteolysis. The NH2-terminal sequence of generated PO was determined to be NH2-Phe-Gly-Glu-Asp-Asp-. The activated PO oxidized o-diphenols but did not oxidize mono-phenol and p-diphenol substrates. The purified pro-PO was not activated by trypsin, alpha-chymotrypsin, and SDS.

Amino Acid Sequence↗
PubMed1997

A triterpenoid saponin from Patrinia scabiosaefolia.

A new triterpenoid saponin, patrinia saponin H3 (3), was isolated from the aerial parts of Patrinia scabiosaefolia Fisch. and determined to be 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-rhamnopyranosyl (1-->2)-alpha-L-arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ester on the basis of NMR and FAB MS experiments and acid hydrolysis.

Carbohydrate Sequence↗
PubMed1997

In vitro antimutagenic effects of anthraquinone aglycones and naphthopyrone glycosides from Cassia tora.

The antimutagenic activity of a methanol extract of Cassia tora seeds against aflatoxin B1(AFB1) was demonstrated with the Salmonella typhimurium assay. The numbers of revertants per plate decreased significantly when this extract was added to the assay system using Salmonella typhimurium TA100 and/or TA98. The MeOH extract was then sequentially partitioned with CH2Cl2, n-BuOH and H2O. The CH2Cl2 and n-BuOH fractions possessed antimutagenic activity but the H2O fraction was inactive. Neither the MeOH extract nor its fractions were capable of inhibiting the direct-acting mutagen N-methyl-N'-nitro-N-nitrosoguanidine suggesting that these fractions may prevent the metabolic activation of AFB1 or scavenge the electrophilic intermediate capable of inducing mutations. Column chromatography using silica gel yielded pure chrysophanol, chryso-obtusin, and aurantio-obtusin from the CH2Cl2 fraction and cassiaside and rubro-fusarin gentiobioside from the n-BuOH fraction. Each of these compounds demonstrated significant antimutagenic activity.

Animals↗
PubMed1997

Cloning and characterization of two catA genes in Acinetobacter lwoffii K24.

Two novel type I catechol 1,2-dioxygenases inducible on aniline media were isolated from Acinetobacter lwoffii K24. Although the two purified enzymes, CD I1 and CD I2, had similar intradiol cleavage activities, they showed different substrate specificities for catechol analogs, physicochemical properties, and amino acid sequences. Two catA genes, catA1 and catA2, encoding by CD I1 and CD I2, respectively, were isolated from the A. lwoffii K24 genomic library by using colony hybridization and PCR. Two DNA fragments containing the catA1 and catA2 genes were located on separate regions of the chromosome. They contained open reading frames encoding 33.4- and 30.4-kDa proteins. The amino acid sequences of the two proteins matched well with previously determined sequences. Interestingly, further analysis of the two DNA fragments revealed the locations of the catB and catC genes as well. Moreover, the DNA fragment containing catA1 had a cluster of genes in the order catB1-catC1-catA1 while the catB2-catA2-catC2 arrangement was found in the catA2 DNA fragment. These results may provide an explanation of the different substrate specificities and physicochemical properties of CD I1 and CD I2.

Acinetobacter↗
PubMed1997

Basal cell adenocarcinoma of the salivary gland--a case report.

Basal cell adenocarcinoma of the salivary gland is a very rare disease entity as the malignant counterpart of basal cell adenoma. On the basis of morphologic pattern, basal cell adenoma can be divided into four subtypes; trabecular, solid, tubular, and dermal analogue (membranous). We report a case of basal cell adenocarcinoma in the left parotid gland of a 33-year-old woman. Light microscopically, the tumor cells were composed of relatively uniform, monotonous basaloid cells. The tumor cell nests commonly had peripheral palisadings. The main growth pattern of the tumor cells was tubulotrabecular. However, other portions were similar to dermal analogue monomorphic adenoma and showed cribriform patterns reminiscent of adenoid cystic carcinoma. The tumor had frequent perineural invasions and an infiltrative margin. On immunohistochemistry, only scattered numbers of tumor cells showed irregular positive reaction for S-100 protein, suggesting a few myoepithelial cell components of the tumor compared with most tumor cells derived from epithelial cells.

Adenocarcinoma↗
PubMed1997

Significance of postoperative serum level of carcinoembryonic antigen (CEA) and actual half life of CEA in colorectal cancer patients.

The postoperative levels of carcinoembryonic antigen (CEA) and the actual half life (T1/2) of CEA were evaluated to ascertain their potency in predicting the recurrence of colorectal cancer after curative surgery in patients who had an abnormally high level of preoperative carcinoembryonic antigen (CEA, > or = 5 ng/ml). Ninety-four patients who underwent curative surgery were enrolled and 24 patients (25.5%) had recurrence during the follow-up period (median: 30 months, range: 2-69 months). T1/2 of CEA for all patients ranged from 1.2 days to 88.1 days, with a median of 4.4 days. T1/2 of CEA (mean +/- standard deviation) was 11.7 +/- 17.9 days in recurrent patients, whereas it was 6.2 +/- 4.9 days in patients without recurrence (p = 0.0224). The patients' age, gender, size of the tumor, location of the tumor, pre-, and postoperative CEA level, pathologic type of the tumor and Dukes stage had no significance in recurrence. The 1-year, 2-year, and 5-year disease-free survival rates were 95.1%, 81.1%, and 73.8% in patients with postoperative CEA levels less than 5 ng/ml (n = 62), respectively, and 71.4%, 64.8%, and 64.8% in patients with postoperative CEA levels higher than or equal to 5 ng/ml (n = 32), respectively (p = 0.04). Patients were divided into Group S (T1/2 of CEA < 4.4 days, n = 43) and Group L (T1/2 of CEA > or = 4.4 days, n = 51). The 1-year, 2-year, and 5-year disease-free survival rates were 95.3%, 85.1%, and 77.7% in Group S, respectively, and 80%, 67.5%, and 64.1% in Group L, respectively (p = 0.0261). In conclusion, the disease-free survival of colorectal cancer patients was prolonged in patients who had a short T1/2 of CEA or a low level of postoperative CEA. In high-risk colorectal cancer patients with an abnormally high level of preoperative CEA, recurrence may be predicted by checking an early postoperative CEA level and/or by a simple calculation of the actual half life of CEA.

Adolescent↗
PubMed1997

A randomized trial comparing cisplatin plus 5-fluorouracil with or without levamisole in operable gastric cancer.

OBJECTIVES: To determine the effectiveness and toxicity when levamisole was added to the adjuvant combination chemotherapy in patients with operable gastric cancer. METHODS: After en bloc resection of gastric cancer without gross or microscopic evidence of residual disease from April 1991 to December 1992, 100 patients were randomized to 6 months of 5-fluorouracil 1,000 mg/m2/day administered as continuous infusion for 5 days, cisplatin 60 mg/m2/day as intravenous infusion for 1 day with or without levamisole (50 mg every eight hours P.O for a period of three days every 2 weeks for 6 months). This chemotherapy treatment was begun within 2 to 4 weeks after the surgery. The chemotherapy consisted of discrete 5-day courses administered at 4-weeks intervals. All 100 patients are assessable. RESULTS: The fifty patients were assigned to each treatment group. There was no statistical difference and no bias in the distribution of characteristics of the 100 evaluable patients between the two groups. A total of 274 courses of treatment were given in the levamisole group and 260 courses of treatment in non-levamisole group. Eleven patients in each group did not finish planned 6 courses of treatment mainly due to non-compliance. At median follow up of 39 months, 32 patients relapsed 19 in the levamisole group and 13 in the non-levamisole group (p = 0.284). Twenty five patients died of relapsed diseases, 15 in the levamisole group and 10 in the non-levamisole group. The levamisole group tended to show more risk of overall death rate and recurrence than the non-levamisole group. However, this result was not statistically significant at 3 years. The treatment was well tolerated in both treatment groups. The grade 2-3 toxicities were nausea/ vomiting (levamisole, non-levamisole group; 31.7%, 29.3% of treatment courses respectively), diarrhea (7.6%, 8.4%), mucositis (11.6%, 12.3%), and leukopenia (9.8%, 9.6%). CONCLUSION: Levamisole had negative effects on disease-free survival and overall survival when added to adjuvant combination chemotherapy of cisplatin and 5-fluorouracil in patients with operable gastric cancer. Both treatment arms were generally well tolerated and the toxicity profile was similar with or without levamisole.

Adjuvants, Immunologic↗
PubMed1996

Thermal balance of man in water: prediction of deep body temperature change.

Changes in rectal temperature and metabolic rate were continuously monitored in men immersed in water at 15, 20, 25, 30, and 35 degrees C. The subjects (12 healthy male students) wore swimming suits while either resting or doing leg exercise (delta M approximately 60 kcal.h-1.m-2 approximately 70 W.m-2) for 1 h. At all water temperatures below 30 degrees C, the metabolic rate increased but the rectal temperature fell continuously, resulting in hypothermia. The rate of fall in rectal temperature (cooling rate, CR, degrees C.h-1) was inversely proportional to water temperature (Tw, degrees C) according to the equation CR = 3.818-0.109 Tw in resting subjects and CR = 3.434-0.110 Tw in exercising subjects. At a given Tw the cooling rate was greater in resting than in exercising subjects and in lean than in obese subjects. From the relationships between the cooling rate and water temperature the duration of useful activity and the survival time were predicted for resting and exercising subjects of various fatness.

Adult↗
PubMed1996

Veno-occlusive disease (VOD) of the liver in Korean patients following allogeneic bone marrow transplantation (BMT): efficacy of recombinant human tissue plasminogen activator (rt-PA) treatment.

Veno-occlusive disease (VOD) of the liver is a clinical syndrome characterized by hyperbilirubinemia, painful hepatomegaly, and fluid retention. In the bone marrow transplantation (BMT) setting, VOD is caused by dose-intensive chemotherapy and/or radiotherapy used to prepare patients for transplant. VOD occurs in up to 50% of the patients who undergo BMT and is usually associated with a high mortality rate. Until recently, there was no proven effective medical therapy for this condition once it was clinically apparent. We report here on the frequency and treatment result of VOD with rt-PA in our allogeneic BMT patients. Eight patients (median age 28.5 years) underwent allogeneic BMT from December, 1993 to June, 1995 in Asan Medical Center. Six leukemia patients were prepared for BMT with busulfan and cyclophosphmide, while two aplastic anemia patients received cyclophosphamide and antithymocyte globulin. VOD was defined as having two of the following features before day 20 posttransplant: jaundice (bilirubin > or = 2 mg/dL), tender hepatomegaly and/or right upper quadrant pain, ascites and/or unexplained weight gain (> 2% from baseline). All patients who were diagnosed with VOD received rt-PA (10-20 mg/day) and heparin (10,000 U/day). Three (37.5%) of the eight patients developed VOD that occurred between 6 and 10 days posttransplant. All three patients developed jaundice, weight gain, and tender hepatomegaly. Ascites and renal insufficiency occurred in two patients and pleural effusion in one patient. rt-PA and heparin were begun 6 to 26 days posttransplant and rt-PA was administered for 7 to 14 days. All three patients responded to the therapy; bilirubin levels began to decrease at 4 to 13 days from the start of therapy. They are all alive at day 111, 316, and 548 days posttransplant. None of the patients had significant hemorrhagic complications after rt-PA treatment. Prolonged administration of rt-PA was feasible without bleeding episode and it seems that rt-PA may alter the natural course of VOD.

Adolescent↗
PubMed1996

Solid and papillary neoplasms of the pancreas.

Solid and papillary neoplasms of the pancreas, a rare tumor usually found in young female patients, seldom presents with metastasis since it is a tumor with low potential for malignancy. The prognosis for this lesion is much more favorable than that for other pancreatic neoplasms. In an attempt to understand the characteristics and prognosis of this lesion, we reviewed twenty cases treated at the Department of Surgery, Severance Hospital, Yonsei University from 1985 to 1994. The mean age of the patients was 25.6 years (range: 13 to 39 years), and 19 (95%) were women. Chief complaints were palpable mass (50%), pain (45%), and indigestion (5%). In laboratory studies, tumor markers, including CEA, CA125, CA19-9, and aFP were studied in eight patients, and found negative. Other laboratory findings were also nonspecific. These tumors may occur anywhere in the pancreas. In our studies, the tumor was most often located in the tail (45%), and the head (40%) of the pancreas. These were treated by distal pancreatectomy and splenectomy (55%), Whipple's operation (20%), pylorus preserving pancreatoduodenectomy (10%), enucleation (10%) or excision (5%). Significant morbidity or mortality was not observed during hospitalization, and no recurrence or malignant degeneration occurred during the mean follow-up period of 4 years (range: 1 month to 9 years). In conclusion, this study has suggested that the patients with a solid and papillary neoplasm of the pancreas have a good prognosis for successful treatment, if the disease is diagnosed early and the tumor is completely resected. A higher index of suspicion, and more aggressive diagnostic workups are needed in dealing with this disease entity.

Adolescent↗
PubMed1996

Nodal metastasis in the distal mesorectum: need for total mesorectal excision of rectal cancer.

Locoregional failure of rectal cancer is a troublesome problem and a major cause of morbidity and mortality following curative surgery. The mesorectum has been regarded as an important site in local failure after surgery of rectal cancer. Total mesorectal excision (TME) has been raised by some colorectal surgeons to prevent early local recurrence. This study was performed to ascertain the incidence of metastatic lymph nodes in the distal mesorectum (DMR) of the colorectal cancer patient. We also examined the clinicopathologic risk factors of distal mesorectal metastasis. Eight of 53 patients had positive metastatic lymph nodes in DMR. Twenty-seven patients were Dukes B and 26 patients were Dukes C stage. Out of 26 Dukes C patients, 8 patients (30.8%) had metastatic lymph nodes in the DMR. However, there was no significant difference in risk factors between DMR positive and DMR negative patients with Dukes C stage. In conclusion, the incidence of metastatic lymph nodes in DMR was about 30.8%, therefore the mesorectum especially the DMR should be removed completely by total mesorectal excision to eradicate the metastatic lymph nodes which may cause local recurrence.

Aged↗
PubMed1996

Adenomyoepithelioma of the breast--its diagnostic problems and histogenesis.

We report three cases of adenomyoepithelioma of the breast that occurred in middle aged women. The tumor is characterized by a balanced proliferation of epithelial tubules and surrounding myoepithelial cells that are spindle shaped or have clear cytoplasms. The first case mimicked tubular adenoma in the initial biopsy. However, on excision it turned out to be an adenomyoepithelioma of the tubular. The other two cases were lobulated types and had fibroadenomatous areas. The morphologic appearance of this tumor varies, making it misleading to other benign or even malignant lesions. The tumor has a potential for local recurrence, therefore, wide excision is recommended for proper diagnosis and treatment.

Adult↗