Biomedical subjects

Tae-Hyung Kim

Publications and source records attributed to Tae-Hyung Kim.

31 records · Page 2Linked to original sources

PubMed2004

Use of a newly designed multifunctional coil catheter for stent placement in the upper gastrointestinal tract.

PURPOSE: To evaluate the usefulness of a newly designed multifunctional coil catheter for stent placement in patients with upper gastrointestinal tract strictures. MATERIALS AND METHODS: Constructed in our research laboratory, the coil catheter was used in 202 consecutive patients with malignant (n = 191) or corrosive (n = 11) upper gastrointestinal tract strictures. The coil catheter was made of a stainless-steel coil (1.3-mm inner diameter, 1.8-mm outer diameter), a 0.4-mm nitinol wire, a polyolefin tube, and a hemostasis valve. Usefulness of the coil catheter was evaluated based on whether the coil catheter could pass the stricture over a guide wire and whether measurement of the stricture length was possible while the guide wire was in place. RESULTS: The passage of the coil catheter over a guide wire beyond the stricture was technically successful and well tolerated in 199 of 202 patients (99%). Negotiation of a guide wire or a coil catheter through the stricture of the stomach (n = 2) or duodenum (n = 1) under fluoroscopic guidance failed in three patients. In two of these three patients, it was possible to negotiate a guide wire and a coil catheter under combined endoscopic and fluoroscopic guidance; it was not possible in the third. There were no procedure-related complications. CONCLUSION: The newly designed multifunctional coil catheter is useful in stent placement in patients with upper gastrointestinal tract strictures.

Adult↗

PubMed2004

Reduction of tissue hyperplasia with a rhenium-188 mercaptoacetyltriglycine-3-filled balloon: preliminary study in a canine urethral model.

PURPOSE: To evaluate the efficacy of beta-radiation therapy with rhenium-188 mercaptoacetyltriglycine-3 (MAG(3))-filled balloons to reduce tissue hyperplasia secondary to stent placement in 18 canine urethras. MATERIALS AND METHODS: Eight dogs were treated with 188-Re MAG(3)-filled balloon dilation immediately after stent placement and were killed 4 weeks later (group I, n = 4) or 8 weeks later (group II, n = 4). Five dogs were treated with 188-Re MAG(3)-filled balloon dilation 2 weeks after stent placement and were killed 4 weeks after stent placement (group III). The remaining five dogs were treated with conventional balloon dilation immediately after stent placement and were killed 4 weeks later; these animals formed the control group (group IV). Retrograde urethrography (RUG) was performed during follow-up and three histologic parameters were investigated: the number of epithelial layers, papillary projection thickness, and degree of submucosal inflammatory cell infiltration. The areas inside and outside the ends of the stents were evaluated in each case after animal sacrifice. After testing statistical significance of data for RUG and histologic findings in the four study groups, the Mann-Whitney U test was used to compare groups I and II to determine delayed effects of irradiation, groups I and III to determine benefits of delayed irradiation, groups I and IV to determine efficacy of immediate irradiation for reducing tissue hyperplasia, and groups III and IV to determine efficacy of delayed irradiation for reducing tissue hyperplasia. RESULTS: There were no significant differences in the four study groups on RUG before animal sacrifice. Between groups I and II, group II showed significantly lower mean values in five of six histologic comparisons. Between groups I and III, group III showed significantly lower mean values in only papillary projection thickness inside the stent ends. Between groups I and IV, group I showed significantly lower mean values in all three histologic parameters outside the stent ends. Between groups III and IV, group III showed significantly lower mean values in only two histologic parameters (papillary projection thickness in the in-stent area and inflammatory cell infiltration outside the stent edges). CONCLUSION: beta-Irradiation with use of a 188-Re MAG(3)-filled balloon shows the potential to reduce tissue hyperplasia secondary to stent placement in a canine urethral model. Treatment with 188-Re MAG(3)-filled balloons at the time of stent placement shows not only favorable outcomes for reducing tissue hyperplasia but also improved delayed effects until 8 weeks.

Animals↗

PubMed2003

Obstruction of the lacrimal system: treatment with a covered, retrievable, expandable nitinol stent versus a lacrimal polyurethane stent.

PURPOSE: To compare the clinical effectiveness of a covered nitinol stent with that of a polyurethane stent for treatment of lacrimal system obstructions. MATERIALS AND METHODS: A nitinol stent was knit from a single thread of 0.1-mm nitinol wire in a tubular configuration and was covered by dipping the stent into a polyurethane solution. The stent was 4 mm in diameter and 30 or 35 mm long. With fluoroscopic guidance, a covered nitinol stent (n = 33, group A) or a polyurethane stent (n = 35, group B) was placed in 68 patients. The following items were evaluated retrospectively: technical success, procedure time, cumulative patency rate, and complications. An unpaired Student t test was used to analyze the difference between the procedure times. Kaplan-Meier survival curves and a log-rank test were used to compare the cumulative patency rates. RESULTS: Stent placement was technically successful in 31 (94%) of 33 patients in group A and in all 35 (100%) patients in group B. After stent placement, all patients showed resolution of epiphora. Average procedure time was 400 seconds (range, 270-900 seconds) in group A and 260 seconds (range, 150-900 seconds) in group B. The difference between the procedure times was statistically significant (P =.0003). During the mean follow-up period of 40 months, there was recurrence of epiphora in 30 of 31 patients in group A and 26 of 35 patients in group B. The difference of the cumulative patency rates was statistically insignificant (P =.2). CONCLUSION: Although the polyurethane stent used for treatment seemed to be more effective than the nitinol stent, selection of these stents for placement should be made with caution, because the long-term patency rates are not encouraging.

Adolescent↗

PubMed2003

Molecular phylogeny and evolution of the human endogenous retrovirus HERV-W LTR family in hominoid primates.

Long terminal repeats (LTRs) of human endogenous retrovirus (HERV) have contributed to the structural change or genetic variation of primate genome that are connected to speciation and evolution. Using genomic DNAs that were derived from hominoid primates (chimpanzee, gorilla, orangutan, and gibbon), we performed PCR amplification and identified thirty HERV-W LTR elements. These LTR elements showed a 82-98% sequence similarity with HERV-W LTR (AF072500). Specifically, additional sequences (GCCACCACCACTGTTT in the gorilla and TGCTGCTGACTCCCATCC in the gibbon) were noticed. Clone OR3 from the orangutan and clone GI2 from the gibbon showed a 100% sequence similarity, although they are different species. This indicates that both LTR elements were proliferated during the last 2 to 5 million years from the integration of the original LTR element. A phylogenetic tree that was obtained by the neighbor-joining method revealed a wide overlap of the LTR elements across species, suggesting that the HERV-W LTR family evolved independently during the hominoid evolution.

Amino Acid Sequence↗

PubMed2003

Use of surfactant modified ultrafiltration for perchlorate (Cl(O)(4-)) removal.

Determinations of perchlorate anion (ClO(4)(-)) transport and rejection were performed using a surfactant modified ultrafiltration (UF) membrane. Perchlorate anion (at a concentration of 100 microg/L of ClO(4)(-), spiked with KClO(4)) was introduced to the membrane as a pure component, in binary mixtures with other salts, cationic and anionic surfactants, and at various ionic strength conditions (conductivity). Also, a natural source water was spiked with perchlorate in the presence of cationic and anionic surfactants and used to determine the effects of a complex mixture (including natural organic matter (NOM)) on the observed rejection. All filtration measurements were performed at approximately the same permeate flow rate in order to minimize artifacts from mass transfer at the membrane interface. The objective of this study was to modify a negatively charged UF membrane in terms of the fundamental mechanisms, steric/size exclusion and electrostatic exclusion and to enhance perchlorate rejection, with synthetic water and a blend of Colorado River water and State Project water (CRW/SPW). Previous work suggested that perchlorate was dominantly rejected by electrostatic exclusion for charged nanofiltration (NF) and UF membranes (Rejection of perchlorate by reverse osmosis, nanofiltration and ultrafiltration (UF) membranes: mechanism and modeling. Ph.D. dissertation, University of Colorado, Boulder, USA, 2001). In that research, perchlorate rejection capability was quickly lost in the presence of a sufficient amount of other ions. However, this study showed that ClO(4)(-) was excluded from a (negatively) charged UF membrane with pores large with respect to the size of the ion. Although perchlorate rejection capability due to apparent electrostatic force was reduced in the presence of a cationic surfactant, a desired amount of the ClO(4)(-) was excluded by steric exclusion. The steric exclusion was due to decreasing membrane pore size caused by the adsorption of the cationic surfactant.

Filtration↗

PubMed2003

Liver cirrhosis developed after ketoconazole-induced acute hepatic injury.

We describe a previously healthy woman who developed liver cirrhosis as a sequela of acute hepatic injury that was induced by ketoconazole administration to treat onychomycosis. The initial presentation of the disease was of a typical acute hepatitis, characterized by nausea, anorexia, fatigue, and jaundice that developed during the administration of ketoconazole. Many other causes of hepatitis were absent in the patient. Even though the hepatic injury was gradually resolved for several months after cessation of the drug, the liver function was not completely restored. Six months after the onset of illness, a follow-up abdominal computed tomography and peritoneoscopic liver biopsy were performed. They revealed a marked reduction in the liver volume and a definite cirrhotic change, which persisted for more than 5 years. The case suggests that the administration of ketoconazole can cause liver cirrhosis through acute hepatic injury within a short time under certain circumstances.

Adult↗

PubMed2003

Newly designed multifunctional coil catheter for gastrointestinal intervention: feasibility determined by experimental study in dogs.

RATIONALE AND OBJECTIVE: Conventional vascular catheters or sizing catheters are often inconvenient and time-consuming for gastrointestinal procedures. Our purpose was to evaluate the feasibility of a newly designed coil catheter by experimental study in dogs. MATERIALS AND METHODS: Two catheter models were fabricated using a stainless-steel coil covered by heat shrinkable tube. The distal uncovered coil part was not elongated in model A but was elongated in model B. We developed 3 different types in each model: types II and III had 65-cm and 240-cm nitinol wires on the coil surfaces, respectively, but no wire was attached in type I. On the middle covered coil part, multiple holes were made into which to inject contrast medium, and multiple radiopaque markers were attached. In an experimental study using 4 mongrel dogs, we evaluated the ability of the coil catheter to pass over a guide wire to 30 cm distal from the pylorus, the ability of contrast to pass through the injection holes, the visibility of the radiopaque markers, and the ability of the coil catheter to be pushed without a guide wire to 120 cm distal from the pylorus. RESULTS: All catheters were successfully passed to 30 cm distal from the pylorus. Contrast passage through the injection holes and visualization of the radiopaque markers were excellent. To advance to 120 cm distal from the pylorus, the average success rates of models A and B were 100% and 69%, respectively. In particular, model A type II showed the best results in average success rate and average number of trials to achieve success. CONCLUSION: This experimental study demonstrated the feasibility of the newly designed coil catheter for gastrointestinal intervention.

Animals↗

PubMed2003

Malignant tracheobronchial strictures: palliation with covered retrievable expandable nitinol stent.

PURPOSE: To evaluate the safety and clinical effectiveness of a covered retrievable expandable nitinol stent for the treatment of malignant tracheobronchial stricture and/or esophagorespiratory fistula (ERF). MATERIALS AND METHODS: With fluoroscopic guidance, stents were placed in 35 symptomatic patients with malignant tracheobronchial stricture and/or ERF in most cases caused by lung or esophageal cancer. The site of stricture was most commonly at the trachea or left main bronchus. If there were complications, the stent was removed with a retrieval set. Nine patients had combined symptomatic ERF. RESULTS: A total of 47 tracheobronchial stents were placed and were technically successful and well-tolerated in all patients. Improvement of dyspnea was achieved in 92% of the patients (24 of 26 patients). Associated ERF in nine patients was effectively treated with tracheobronchial stent placement with or without esophageal stent placement. Stent migration, tumor overgrowth, symptomatic sputum retention, and hemoptysis occurred in 17% (6/35), 6% (2/35), 20% (7/35), and 17% (6/35) of patients, respectively. There were no documented cases of tumor ingrowth. Stent removal was performed easily in five patients when stent migration (n = 2), severe pain (n = 1), tumor overgrowth (n = 1), or persistent gastrobronchial fistula (n = 1) developed. All patients died 2 days to 26 weeks (mean, 9.62 weeks) after stent placement because of disease progression (n = 18), pneumonia (n = 9), hemoptysis (n = 5), or unknown cause (n = 3). CONCLUSION: Use of a covered retrievable expandable nitinol stent is a safe and effective method for relieving dyspnea. This procedure contributed to improved quality of life for patients with malignant tracheobronchial stricture and/or ERF. Stent retrievability was useful in resolving stent-related complications.

Adult↗

PubMed2003

Recurrent traumatic urethral strictures near the external sphincter: treatment with a covered, retrievable, expandable nitinol stent--initial results.

PURPOSE: To investigate the clinical effectiveness of a covered, retrievable, expandable nitinol stent in treating traumatic urethral strictures near the external sphincter. MATERIALS AND METHODS: The stent was 10 mm in diameter when fully expanded and 40-50 mm long. To make it removable, two nylon drawstrings were attached to its lower inner margin. Twelve consecutive men (19-67 years; mean age, 47 years) with traumatic urethral strictures near the external sphincter that were refractory to endoscopic urethrotomy were treated. With fluoroscopic guidance, a stent was placed to completely bridge the external sphincter. The stent was electively removed with a retrieval hook wire 2 months after placement. Stent placement and removal were successful in all patients, with no procedural complications. RESULTS: Mean maximum urine flow rate was 5 mL/sec (range, 3-7 mL/sec) before stent placement and 27 mL/sec (range, 16-40 mL/sec) at 1 week after placement. During the mean follow-up of 20 months (range, 2-37 months) after the first stent removal, strictures recurred in eight of 12 patients. For the eight patients with recurrence, a second stent was placed and 4 months later was removed from seven of the eight patients. During the mean follow-up of 18 months (range, 4-32 months) after the second stent removal, strictures recurred in two patients, in whom a third stent was placed and then removed 4 months later, with good results. Four (33%) of 12 patients, five (62%) of eight patients, and two (100%) of two patients were successfully treated with placement of the first stent, the second stent, and the third stent, respectively. In the remaining patient, the second stent remains in place. CONCLUSION: Placement of a covered, retrievable, expandable nitinol stent seems to be effective in treating urethral strictures near the external sphincter and warrants further investigation.

Adult↗

PubMed2002

Synthesis, characterization and in vtro identification of N7-guanine adduct of 2-bromopropane.

Recently, we have reported that 2-bromopropane might have an immunotoxic potential in rats when exposed for 28 days. In the present studies, the possibility of 2i-deoxyguanosine adduct formation by 2-bromopropane was investigated in vitro to elucidate molecular mechanism of 2-bromopropane-induced immunosuppression. N7-Guanine adduct of 2'-bromopropane (i.e., N7-isopropyl guanine) was chemically synthesized and structurally characterized by analysis of UV, 1H-NMR, '3C-NMR, COSY and fast atom bombardment mass spectrometry to use as a reference material. Incubation of 2'-deoxyguanosine with an excess amount of 2-bromopropane in PBS buffer solution, pH 7.4, at 37 degrees C for 16 h, followed by a thermal hydrolysis, produced a detectable amount of N7-isopropyl guanine by an HPLC and UV analysis. The present results suggest that 2-bromopropane might form a DNA adduct in N7 position of 2'-deoxyguanosine at a physiological condition.

Chromatography, High Pressure Liquid↗

PubMed2002

Differential suppression of human cervical cancer cell growth by adenovirus delivery of p53 in vitro: arrest phase of cell cycle is dependent on cell line.

It has been reported that overexpression of wild-type p53 protein induces suppression of tumor cell growth in vivo and in vitro. In this study, we further evaluated the differential effects of p53 delivered in an adenovirus vector on the cell growth, apoptosis and cell cycle progression in cervical cancer cell lines. We constructed a recombinant adenovirus expressing p53 and then delivered this into cervical carcinoma cell lines (CaSki, SiHa, and HeLa, HeLaS3) along with adenovirus expressing beta-galactosidase as a negative control. Adenovirus-delivered p53 overexpression resulted in a more significant suppression of cell growth in HPV 18-infected cells (HeLa and HeLaS3) and a lesser suppression in HPV 16-infected cells (CaSki and SiHa). However, no suppression was observed in cells infected with a negative control virus. p53 overexpression also induced apoptosis and cell cycle arrest, as determined by annexin V and propidium iodide staining. In particular, the cell cycle was arrested in the G(2)/M phase in CaSki cells. In contrast, cell cycles were arrested in the G(1) phase in HeLa cells, suggesting that the arrest phase is dependent upon the cervical cancer cell line. Taken together, these data support the idea that overexpressed p53 protein plays a differential role in suppressing cervical cancer cell growth through apoptosis and cell cycle arrest in either G(1) or G(2)/M phase, depending on the cancer cell line.

Adenoviridae↗

PubMed2002

Covered, retrievable, expandable urethral nitinol stent: feasibility study in dogs.

PURPOSE: To evaluate the feasibility of using a retrievable urethral stent and to evaluate whether granulation tissue resolves after stent removal in a canine urethra. MATERIALS AND METHODS: Polyurethane-covered retrievable 0.10-mm-thick (n = 11) or 0.15-mm-thick (n = 10) nitinol wire stents were placed in the urethras of 20 dogs. In one dog, a second stent was placed in the urethra because of complete migration of the first stent into the urinary bladder. The stents were removed with retrieval hook wires 4 weeks (n = 10) and 8 weeks (n = 10) after placement. Fourteen dogs were sacrificed just after stent removal, and the other six dogs were sacrificed 2 weeks after stent removal. Information concerning procedure success, stent migration, and tissue response was obtained. RESULTS: Stent placement was technically successful in all dogs. Follow-up urethrograms showed partial (n = 4) or complete (n = 1) stent migration. Stent removal failed in two dogs due to partial or complete migration. Granulation tissue was observed at both ends of the stent in 17 dogs. Urethrograms and urethral specimens obtained 2 weeks after stent removal showed diminished granulation tissue and decreased thickness of the papillary projections of the epithelium compared with results obtained immediately after stent removal. CONCLUSION: Although some design modifications are necessary to reduce current complications, the polyurethane-covered retrievable nitinol stent seems feasible for use in the urethra. Stent-induced granulation tissue formation improved after stent removal.

Alloys↗

PubMedDate not supplied

Balloon sheaths for gastrointestinal guidance and access: a preliminary phantom study.

OBJECTIVE: We wanted to evaluate the feasibility and usefulness of a newly designed balloon sheath for gastrointestinal guidance and access by conducting a phantom study. MATERIALS AND METHODS: The newly designed balloon sheath consisted of an introducer sheath and a supporting balloon. A coil catheter was advanced over a guide wire into two gastroduodenal phantoms (one was with stricture and one was without stricture); group I was without a balloon sheath, group ll was with a deflated balloon sheath, and groups III and IV were with an inflated balloon and with the balloon in the fundus and body, respectively. Each test was performed for 2 minutes and it was repeated 10 times in each group by two researchers, and the positions reached by the catheter tip were recorded. RESULTS: Both researchers had better performances with both phantoms in order of group IV, III, II and I. In group IV, both researchers advanced the catheter tip through the fourth duodenal segment in both the phantoms. In group I, however, the catheter tip never reached the third duodenal segment in both the phantoms by both the researchers. The numeric values for the four study groups were significantly different for both the phantoms (p < 0.001). A significant difference was also found between group III and IV for both phantoms (p < 0.001). CONCLUSION: The balloon sheath seems to be feasible for clinical use, and it has good clinical potential for gastrointestinal guidance and access, particularly when the inflated balloon is placed in the gastric body.

Catheterization↗