Biomedical subjects

Tae-Sun Shim

Publications and source records attributed to Tae-Sun Shim.

7 recordsLinked to original sources

PubMed2006

Treatment of tracheobronchial obstruction with a polytetrafluoroethylene-covered retrievable expandable nitinol stent.

PURPOSE: To evaluate the clinical effectiveness of polytetrafluoroethylene (PTFE)-covered retrievable expandable nitinol stents in tracheobronchial strictures. MATERIALS AND METHODS: With fluoroscopic guidance, PTFE-covered retrievable expandable nitinol stents were placed in 15 symptomatic patients with benign (n = 6) or malignant (n = 9) tracheobronchial strictures. Complications and improvement in respiratory status were evaluated. Stents were removed electively 6 months after placement in benign strictures or if complications occurred. Membrane degradation or separation from the wire mesh was evaluated in removed stents. RESULTS: A total of 17 stents were successfully placed and were well tolerated in all patients. Sputum retention, stent migration, and tissue hyperplasia occurred in 23.5% (n = 4), 17.6% (n = 3), and 17.6% (n = 3) of stents, respectively. A total of 11 stents were successfully removed electively 6 months after placement (n = 4) or when complications occurred (n = 7). All 11 such stents were removed without difficulty with use of standard techniques, antecedent balloon dilation being necessary in two cases as a result of tissue hyperplasia. No removed stent showed signs of membrane degradation, and two removed stents showed signs of membrane separation from the mesh. CONCLUSIONS: PTFE-covered retrievable expandable nitinol stents were effective in the treatment of tracheobronchial strictures. Stent removal was easy with use of standard techniques, and no removed stent showed evidence of membrane degradation.

Adolescent↗

PubMed2005

Simvastatin inhibits cigarette smoking-induced emphysema and pulmonary hypertension in rat lungs.

RATIONALE: In cigarette smoking-induced chronic obstructive pulmonary disease, structural and functional derangements are characterized by parenchymal destruction and pulmonary hypertension. Statins are 3-hydroxy-3-methyl-glutaryl-coenzyme-A reductase inhibitors that have been used as lipid-lowering agents. These drugs also have additional pharmacologic properties, including antiinflammation, scavenging reactive oxygen species, restoring endothelial function, and antithrombogenesis, all of which can counteract the harmful effects of cigarette smoking. OBJECTIVE: We performed assays to determine whether simvastatin could attenuate lung damage induced by chronic cigarette smoking in rats. METHODS: In Sprague-Dawley rats exposed to cigarette smoke for 16 weeks, morphologic changes in the lungs and pulmonary arterial pressure were examined. MAIN RESULTS: Simvastatin inhibited lung parenchymal destruction and development of pulmonary hypertension, and also inhibited peribronchial and perivascular infiltration of inflammatory cells and induction of matrix metalloproteinase-9 activity in lung tissue. Simvastatin additionally prevented pulmonary vascular remodeling and the changes in endothelial nitric oxide synthase expression induced by smoking. In human lung microvascular endothelial cells, simvastatin increased expression of endothelial nitric oxide synthase mRNA. CONCLUSIONS: Simvastatin ameliorated the structural and functional derangements of the lungs caused by cigarette smoking, partly by suppressing inflammation and matrix metalloproteinase-9 induction and preventing pulmonary vascular abnormality. These findings indicate that statins may play a role in the treatment of cigarette smoking-induced chronic obstructive pulmonary disease.

Administration, Oral↗

PubMed2005

PCR restriction fragment length polymorphism analysis (PRA)-algorithm targeting 644 bp Heat Shock Protein 65 (hsp65) gene for differentiation of Mycobacterium spp.

A method based on PCR-restriction fragment length polymorphism analysis (PRA) using a novel region of the hsp65 gene was developed for the rapid and exact identification of mycobacteria to the species level. A 644 bp region of hsp65 in 62 mycobacteria reference strains, and 4 related bacterial strains were amplified, and the amplified DNAs were subsequently digested with restriction enzymes, namely, AvaII, HphI, and HpaII. Most of the mycobacteria species were easily differentiated at the species level by the developed method. In particular, the method enabled the separation of M. avium, M. intracellulare and M. tuberculosis to the species level by AvaII digestion alone. An algorithm was constructed based on the results and a blind test was successfully performed on 251 clinical isolates, which had been characterized by conventional biochemical testing. Our results suggest that this novel PRA offers a simple, rapid, and accurate method for the identification of mycobacteria culture isolates at the species level.

Algorithms↗

PubMed2005

Differentiation of Mycobacterium species by analysis of the heat-shock protein 65 gene (hsp65).

The nucleotide sequences (604 bp) of partial heat-shock protein genes (hsp65) from 161 Mycobacterium strains containing 56 reference Mycobacterium species and 105 clinical isolates were determined and compared. hsp65 sequence analysis showed a higher degree of divergence between Mycobacterium species than did 16S rRNA gene analysis. Generally, the topology of the phylogenetic tree based on the hsp65 DNA sequences was similar to that of the 16S rRNA gene, thus revealing natural relationships among Mycobacterium species. When a direct sequencing protocol targeting 422 bp sequences was applied to 70 non-tuberculous mycobacterium (NTM) clinical isolates, all NTMs were clearly identified. In addition, an XhoI PCR restriction fragment length polymorphism analysis method for the differentiation of Mycobacterium tuberculosis complex from NTM strains was developed during this study. The results obtained suggest that 604 bp hsp65 sequences are useful for the phylogenetic analysis and species identification of mycobacteria.

Bacterial Proteins↗

PubMed2005

The effects of methylene blue on hemodynamic parameters and cytokine levels in refractory septic shock.

BACKGROUND: Endogenous nitric oxide (NO) induces the peripheral vasodilation via the activation of guanylate cyclase in patients with septic shock. The purpose of this study was to assess the acute effects of methylene blue (MB), which is an inhibitor of guanylate cyclase, on the hemodynamics and on the production of pro-inflammatory cytokines and nitric oxide (NO) in patients with refractory septic shock. METHODS: Twenty consecutive patients with refractory septic shock, which was defined as shock refractory to a dopamine infusion of more than 20 microg/kg/min with the appropriate use of antibiotics and adequate volume replacement, received MB infusion of 1 mg/kg intravenously. The hemodynamic and respiratory variables were measured at baseline, 30, 60 and 120 min after an infusion of MB (1 mg/kg). The blood levels of NO, IL-1, IL-10 and TNF-alpha were measured at baseline, 30 and 120 min after MB infusion. RESULTS: The administration of MB induced an increase in the systemic vascular resistance (SVR) that resulted in an increase of the mean arterial pressure (MAP) in patients with refractory septic shock, and this was without a decrease in cardiac output. The administered MB induced an increase in pulmonary vascular resistance (PVR) that resulted in an increase of pulmonary arterial pressure (PAP), without any deterioration of gas exchange. However, the increases in SVR and PVR were not associated with the alteration of endogenous production of NO, IL-1, IL-10 and TNF- alpha. CONCLUSION: MB transiently elevated the MAP by increasing the SVR without altering the endogenous productions of NO, IL-1, IL-10 and TNF- alpha during the study period in patients with refractory septic shock.

Anti-Infective Agents, Urinary↗

PubMed2003

Effect of alveolar recruitment maneuver in early acute respiratory distress syndrome according to antiderecruitment strategy, etiological category of diffuse lung injury, and body position of the patient.

OBJECTIVE: To assess how the level of positive end-expiratory pressure (PEEP) (antiderecruitment strategy), etiological category of diffuse lung injury, and body position of the patient modify the effect of the alveolar recruitment maneuver (ARM) in acute respiratory distress syndrome (ARDS). DESIGN: Prospective clinical trial. SETTING: Medical intensive care unit at a tertiary hospital. PATIENTS: Forty-seven patients with early ARDS, including 19 patients from our preliminary study. INTERVENTION: From baseline ventilation at a tidal volume of 8 mL/kg and PEEP of 10 cm H2O, the ARM (a stepwise increase in the level of PEEP up to 30 cm H2O with a concomitant decrease in the magnitude of tidal volume down to 2 mL/kg) was given with (ARM + PEEP, n = 20) or without (ARM only, n = 19) subsequent increase of PEEP to 15 cm H2O. In eight other patients, PEEP was increased to 15 cm H2O without a preceding ARM (PEEP only). MEASUREMENTS AND RESULTS: In all three groups, Pao2 was increased by the respective intervention (all p<.05). In the ARM-only group, Pao2 at 15 mins after intervention was lower than Pao2 immediate after intervention (p =.046). In the ARM + PEEP group, no such decrease in Pao2 was observed, and Pao2 at 15, 30, 45, and 60 mins after intervention was higher than in the ARM-only group (all p<.05). Compared with the PEEP-only group, Pao2 of the ARM + PEEP group was higher immediately after intervention and at the later time points (all p <.05). Compared with patients with ARDS associated with direct lung injury (pulmonary ARDS), patients with ARDS associated with indirect lung injury (extrapulmonary ARDS) showed a greater increase in Pao2 (27 +/- 21% vs. 130 +/- 112%; p=.002) and a greater decrease in radiologic scores (1.0 +/- 2.4 vs. 3.4 +/- 1.5; p=.005) after the ARM. The increase in Pao2 induced by the ARM was greater for patients in the supine position than for patients in the prone position (61 +/- 82% vs. 21 +/- 14%; p=.028). Consequently, Pao immediately after the ARM was similar in the two groups of patients in different positions. CONCLUSIONS: After the ARM, a sufficient level of PEEP is required as an antiderecruitment strategy. Pulmonary ARDS and extrapulmonary ARDS may be different pathophysiologic entities. An effective ARM may obviate the need for the prone position in ARDS at least in terms of oxygenation.

Female↗

PubMed2002

Physiologic characteristics of cold perfluorocarbon-induced hypothermia during partial liquid ventilation in normal rabbits.

UNLABELLED: Because perfluorocarbon (PFC) liquid contacts closely with the alveolar capillaries during partial liquid ventilation (PLV), PLV with cold PFC may be used for the induction of hypothermia. Twenty rabbits were randomized to PFC-induced hypothermia (PH) (n = 7; core temperature 35 degrees +/- 1 degrees C), surface hypothermia (SH) (n = 7; 35 degrees +/- 1 degrees C), or normothermia (n = 6; 39 degrees +/- 1 degrees C). We induced PH by repeated in situ exchanges of 0 degrees C perfluorodecalin during PLV. At the establishment (0 min) of hypothermia in the PH group, oxygen consumption (P = 0.04) and oxygen extraction ratio (P = 0.01) decreased from normothermic condition. Metabolic (oxygen consumption, oxygen extraction ratio, serum lactate level) and hemodynamic variables (heart rate, blood pressure, cardiac output, pulmonary artery pressure) of the PH group were not different from those of the SH group at 0, 30, 60, 90, and 120 min of hypothermia. The difference in temperature between the pulmonary artery and rectum during the hypothermic period was smaller in the PH group compared with the SH group (P = 0.033). In conclusion, hypothermia may be induced during PLV by using cold PFC. This "pulmonary method" of cooling was comparable to a systemic method of cooling with regard to a few important physiologic variables, while maintaining a narrower interorgan temperature difference. IMPLICATIONS: The induction of moderate hypothermia was feasible in rabbits by administrating cold perfluorocarbon liquid into the lung. Physiologic changes induced by this pulmonary cooling were comparable to those induced by systemic cooling. Our method may be regarded as a methodological advance in the field of therapeutic hypothermia.

Animals↗