Biomedical subjects

Y Jeon

Publications and source records attributed to Y Jeon.

At least 19 recordsLinked to original sources

PubMed2006

Intrathecal implants of microencapsulated xenogenic chromaffin cells provide a long-term source of analgesic substances.

Adrenal medullary chromaffin cells secrete several neuroactive substances including catecholamines and opioid peptides that produce analgesic effects in the central nervous system. This study was designed to investigate whether intrathecal microencapsulated chromaffin cells could release analgesic materials producing antiallodynic effects on the chronic neuropathic pain in rats induced by chronic constriction injury (CCI) of the sciatic nerve. Prior to intrathecal implantation, chromaffin cells were encapsulated with alginate and poly-L-lysine to protect them from the host immune system. Behavior tests were performed before CCI, 1 week later, and at 4, 7, 14, 21, 28 days postimplantation. At the end of study, we performed cerebrospinal fluid (CSF) collection and implant retrieval. We observed that intrathecal implantation of encapsulated xenogenic chromaffin cells reduced the mechanical and cold allodynia in a model of neuropathic pain. CSF levels of catecholamines and metenkephalin in the rats that received implants were higher than the controls. In addition, we observed chronic survival of implants. These results suggested that intrathecal microencapsulated chromaffin cells may represent a new approach to chronic neuropathic pain management.

Absorbable Implants↗

PubMed2005

Effects of epidural naloxone on pruritus induced by epidural morphine: a randomized controlled trial.

BACKGROUND: Epidural morphine produces prolonged analgesia but has many side effects including pruritus. Naloxone is an antagonist that can reverse the side effects of morphine. METHOD: We studied the effects of continuously administered epidural naloxone mixed with morphine on side effects and analgesia in a randomized, double blind, two-armed study. Fifty-eight pregnant women undergoing cesarean section were enrolled. All patients received a 4-mg epidural bolus of morphine in the post-anesthetic care unit. After this, patients in group M (n=28) received continuous epidural morphine (6 mg over 48 h) in 0.1% bupivacaine; patients in group N (n=30) received an epidural infusion containing naloxone (1.2 mg over 48 h) and morphine (6 mg over 48 h) in 0.1% bupivacaine. The infusion rate was 2 mL/h. RESULTS: The incidence (82% versus 47%) and severity of pruritus were lower in group N than group M (P=0.001). There were no significant differences in pain score or in the incidence of nausea, vomiting or urinary disturbance between groups. CONCLUSION: Continuous epidural infusion of naloxone combined with morphine is effective in reducing the incidence and severity of pruritus induced by epidural morphine.

Adult↗

PubMed2005

Influence of orientations of guidewire tip on the placement of subclavian venous catheters.

BACKGROUND: The role of a J-type guidewire tip has been known to prevent vascular or cardiac wall damage. We hypothesized that the course of the guidewire may be influenced by the initial orientations of the J-type guidewire tip during the subclavian approach. The purpose of this study was to investigate the influence of the direction of the needle bevel and J-wire tip on successful placement of subclavian catheters. METHODS: A total of 140 adult patients of either sex were studied. Patients were randomly divided by the direction of the needle bevel (neutral vs. downward) and the direction of the J-wire tip (upward vs. downward). Under general anesthesia, right infraclavicular subclavian catheterization was attempted using the Seldinger technique. RESULTS: There was no statistically significant difference among the successful and unsuccessful placements in relation to factors including sex, body mass index, and needle bevel direction. The success rate was high when the J-wire tip was directed downward (P = 0.001). CONCLUSION: These data suggest that the orientation of the J-wire tip downward can increase successful placement rates of right subclavian venous catheterization.

Aged↗

PubMed2005

Comparison of alfetanil and ketamine in combination with propofol for patient-controlled sedation during fiberoptic bronchoscopy.

BACKGROUND: During fiberoptic bronchoscopy, propofol, ketamine, benzodiazepines, and opiates are most commonly used, alone or in combination for sedation. The aim of this study was to compare the clinical efficacy of propofol/ketamine with propofol/alfentanil for patient-controlled sedation (PCS) during fiberoptic bronchoscopy. METHOD: Patients undergoing fiberoptic bronchoscopy were randomly assigned to receive either propofol/alfentanil (PA group; n = 138) or propofol/ketamine (PK group; n = 138) via a patient-controlled analgesia (PCA) device for sedation and analgesia. Changes in blood pressure, heart rate (HR), and oxygen saturation were monitored. Degree of patient and bronchoscopist satisfaction was evaluated using a 10-cm visual analog scale (VAS) (0 = extremely uncomfortable to 10 = extremely comfortable). RESULTS: After sedation, systolic arterial pressure (SAP) decreased in the PA group, but SAP was stable in the PK group. Compared with values immediately before starting bronchoscopy, SAP and HR increased during the procedure in both groups (P < 0.05). Patients in the PK group showed more satisfaction [(9.5 (6-10) vs. 9.0 (6-10)), P < 0.05] and amnesia (82% vs. 61%, P < 0.01). Despite these differences, the majority (greater than 90%) of the patients in both groups stated that they were comfortable during the procedure. CONCLUSION: Our results show that although both techniques proved effective for sedation in patients undergoing fiberoptic bronchoscopy, ketamine is superior to alfentanil when used in combination with propofol because of the high patient satisfaction and amnesia.

Adolescent↗

PubMed2005

A new technique to determine the size of double-lumen endobronchial tubes by the two perpendicularly measured bronchial diameters.

The cross-section of the mainstem bronchi is not completely round. For preoperative selection of a double-lumen endobronchial tube size, it may be necessary to measure the mediolateral and the anteroposterior bronchial diameters, which can be measured respectively on chest radiograph and computed tomography. With Internal Review Board approval and patients' informed consent, 105 elective thoracic surgical patients who needed left-sided double-lumen tubes were enrolled. Double-lumen tube size was selected depending on the arithmetic mean of the mediolateral and anteroposterior bronchial diameters. Moreover, the outer diameters of the bronchial tube should be smaller than both mediolateral and anteroposterior diameters. The recommended bronchial diameter for each double-lumen tube size was chosen so that the mean of the two bronchial diameters was 0 to 2.0 mm larger than the upper limit of 95% confidence interval of the averaged outer diameter of the bronchial tube of the selected double-lumen tube. In no case was the predicted double-lumen tube size inappropriate. Generally, anteroposterior bronchial diameters appeared to be different from mediolateral diameters (P=0.001). The double-lumen tube size to be selected based on only one bronchial diameter was different from the one selected based on two perpendicularly measured bronchial diameters in 54.3% of patients (57/105). Preoperative selection of the double-lumen tube size based on the anteroposterior, mediolateral and mean bronchial diameters seems to be useful in that this may obviate the need to change an inappropriately sized double-lumen tube and may be helpful in reducing the related complications.

Adult↗

PubMed2003

Intravenous clonidine prolongs bupivacaine spinal anesthesia.

BACKGROUND: Prolongation of spinal anesthesia by oral clonidine premedication has been known. We hypothesized that intravenous clonidine administered after the spinal block may prolong spinal anesthesia. METHODS: To assess the prolongation of spinal anesthesia by intravenous clonidine, we designed a double-blind, placebo-controlled, prospective study. Patients scheduled for orthopedic surgery received 12 mg of 0.5% hyperbaric bupivacaine and were randomly divided into three groups (n = 26 in each group). In the clonidine 10-min group, 3 microg x kg-1 of clonidine was administered for 10 min immediately after the spinal block. In the clonidine 60-min group, 3 microg x kg-1 of clonidine was administered for 10 min, 50 min after the spinal block. The control group received normal saline. Sensory block was evaluated by pinprick and the duration was defined as the time for sensory block to regress to L1 dermatome. Duration of motor block was defined as the time required for the patient to flex his or her knee. RESULTS: The duration of sensory block was longer in both the clonidine 10-min and clonidine 60-min groups compared with the control group (196 +/- 42 min, 179 +/- 41 min vs. 125 +/- 25 min, P < 0.05). The duration of motor block was longer in the clonidine 10-min group than in the control group (153 +/- 26 min vs. 131 +/- 29 min, P < 0.05). The lowest heart rate and mean blood pressure were not different among groups. CONCLUSIONS: Intravenous clonidine administration within 1 h after the spinal block prolonged bupivacaine spinal anesthesia for approximately 1 h without adverse effects.

Adult↗

PubMed2001

Multimerization of phosphorylated and non-phosphorylated ArcA is necessary for the response regulator function of the Arc two-component signal transduction system.

To adapt to anaerobic conditions, Escherichia coli operates the Arc two-component signal transduction system, consisting of a sensor kinase, ArcB, and a response regulator, ArcA. ArcA is converted to the active form, phosphorylated ArcA (ArcA-P), by ArcB-mediated phosphorylation. The active ArcA-P binds to the promoter regions of target genes, thereby regulating their transcriptional activities. The phosphoryl group of ArcA-P is unstable with a half-life of 30 min. However, we were able to inhibit the dephosphorylation for more than 12 h by the addition of EDTA; this allowed us to characterize ArcA-P. Gel-filtration and glycerol sedimentation experiments demonstrated that ArcA exists as a homo-dimer. ArcA phosphorylated by either ArcB or carbamyl phosphate multimerizes to form a tetramer of dimers; this multimer binds to the ArcA DNA binding site. Isoelectric focusing gel electrophoresis and nitrocellulose-filter binding analyses indicated that the ArcA multimer is composed of both ArcA-P and ArcA in a ratio, 1:1. The ArcA(D54E) mutant protein was unable to be phosphorylated by ArcB. This defect resulted in the inability of ArcA(D54E) to form a multimer or to bind to the ArcA DNA binding site. These results indicate that phosphorylation of ArcA induces multimerization prior to DNA binding, and the multimerization is a prerequisite for binding. Our results suggest a novel model that phosphorylation of ArcA by ArcB regulates multimerization of ArcA, which in turn functions as a response regulator.

Bacterial Outer Membrane Proteins↗

PubMed2000

The arc two-component signal transduction system inhibits in vitro Escherichia coli chromosomal initiation.

Under anaerobic growth conditions, Escherichia coli operates a two-component signal transduction system, termed Arc, that consists of ArcB protein, a transmembrane sensor kinase and ArcA protein, the cognate response regulator. In response to low oxygen levels, autophosphorylated ArcB phosphorylates ArcA, and the resulting phosphorylated ArcA (ArcA-P) functions as a transcriptional regulator of the genes necessary to maintain anaerobic growth. Under anaerobic conditions, cells maintain a slow growth rate, suggesting that the initiation of chromosomal replication is regulated to reduce the initiation frequency. DNase I footprinting experiments revealed that ArcA-P binds to the left region of the chromosomal origin, oriC. ArcA-P did not affect the in vitro replication of plasmid DNA containing the ColE1 origin nor the in vitro replication of viral DNAs; however, ArcA-P specifically inhibited in vitro E. coli chromosomal replication. This inhibition was caused by the prevention of open complex formation, a necessary step in the initiation of chromosomal replication. Our in vitro results suggest that the Arc two-component system participates in regulating chromosomal initiation under anaerobic growth conditions.

Bacterial Outer Membrane Proteins↗

PubMed2000