Biomedical subjects

Youngho Lee

Publications and source records attributed to Youngho Lee.

5 recordsLinked to original sources

PubMed2006

Elevated contractile responses to acetylcholine in organ cultured rabbit carotid artery.

The aim of the present study was to examine the functional changes that occur when a rabbit carotid artery is cultured in serum-free medium. In endothelium (EC)-intact arteries cultured under serum-free conditions, acetylcholine (ACh)-induced relaxation responses were partially, yet significantly, reduced when compared with freshly isolated arteries. After pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, application of ACh resulted in a significant contraction in organ cultured arteries. The amplitude of the ACh-induced contractions increased with the duration of culture. In EC-denuded arteries cultured under serum-free conditions, ACh induced responses similar to those in EC-intact arteries pretreated with L-NAME. Furthermore, ACh caused a significant increase in intracellular Ca2+ concentration ([Ca2+]i) in EC-denuded arteries cultured under serum-free condition for 7 days. There was little change in either [Ca2+]i or tension in freshly isolated carotid rings. There was no difference in sodium nitroprusside-induced relaxation responses between fresh and cultured arteries. These results suggest that prolonged culture of carotid arteries under serum- free conditions changes the functional properties of vascular reactivity in rabbit carotid arteries.

Acetylcholine↗

PubMed2005

In vitro production and initiation of pregnancies in inter-genus nuclear transfer embryos derived from leopard cat (Prionailurus bengalensis) nuclei fused with domestic cat (Felis silverstris catus) enucleated oocytes.

The leopard cat (Prionailurus bengalensis), a member of the felidae family, is currently listed as threatened by the Ministry of Environment in South Korea. In exotic or endangered species, the lack of oocytes and recipients precludes the use of traditional somatic cell nuclear transfer, and an approach such as inter-genus nuclear transfer may be the only alternative for producing embryos and offspring. In the present study, we used the leopard cat as a somatic cell donor to evaluate the in vivo developmental competence, after transfer into domestic cat recipients, of cloned embryos produced by the fusion of leopard cat fibroblast cell nuclei with domestic cat cytoplasts. A total of 412 enucleated domestic cat oocytes were reconstructed with either male (Group A) or female (Group B) adult leopard cat fibroblasts. There was no significant difference in fusion rate (60.4% versus 56.9%) between Groups A and B. Of the cultured embryos, the cleavage and blastocyst developmental rate were not significantly different between Groups A and B (69.5% versus 60.8%; 7.2% versus 7.8%, P > 0.05). In Group A, in vivo developmental studies at 30-45 days postimplantation demonstrated 4.8% (21/435) of reconstructed embryos (n = 435) had entered into the uterine lining of recipients, while 1.4% (6/435) formed fetuses. However, all of the reconstructed embryos failed to develop to term (65 days). Microsatellite analyses confirmed that the nuclear genome of the cloned fetus were leopard cat in origin.

Animals↗

PubMed2004

Inflammation of the gastric remnant after gastrectomy: mucosal erythema is associated with bile reflux and inflammatory cellular infiltration is associated with Helicobacter pylori infection.

BACKGROUND: Controversy exists concerning the role of bile reflux and Helicobacter pylori ( H. pylori) infection in the development of inflammation of the gastric remnant after gastrectomy. This study was designed to investigate association of bile reflux and H. pylori infection or both with inflammatory changes in the gastric remnant. METHODS: A questionnaire on GI symptoms was returned by 200 gastrectomy patients, and 24-h bilirubin monitoring in the gastric remnant was performed on 55 patients with Bilitec 2000. Upper GI endoscopy evaluated reflux gastritis in the gastric remnant, and the presence of H. pylori infection and chronic, active inflammatory cellular infiltration in the biopsy specimens were examined microscopically with the updated Sydney system. RESULTS: No difference in the incidence of GI symptoms was observed among individual gastrectomy patients. Bile reflux was lower in patients who had undergone a gastrectomy with jejunal interposition, a pylorus-preserving gastrectomy, and a gastrectomy with Roux-Y anastomosis than those who had undergone a Billroth-II (B-II) anastomosis ( P < 0.05). Endoscopy showed positive correlation between mucosal erythema and bile reflux ( P < 0.001). No correlation was observed between the mucosal erythema and chronic and active inflammatory cellular infiltration. Infection of H. pylori correlated with chronic and active inflammatory cellular infiltration ( P < 0.001). Bile reflux did not correlate with the severity of chronic and active inflammatory cellular infiltration or H. pylori infection. CONCLUSIONS: Bile reflux into the gastric remnant was observed by Bilitec 2000. Mucosal erythema and chronic, active inflammatory cell infiltration in the gastric remnant after gastrectomy may be caused by bile reflux or H. pylori infection, respectively.

Bile Reflux↗

PubMed2004

High-resolution transmission electron microscopy study of Ca(3)Co(4)O(9).

The crystal structure of Ca(3)Co(4)O(9) was investigated using high-resolution transmission electron microscopy (HRTEM) and the image-simulation method. The c(*) was 10.8A and the b parameters were 4.56A for the Ca(2)CoO(3) block and 2.82A for the CoO(2) sheet. The [110] zone axis HRTEM images confirmed that Ca(3)Co(4)O(9) has a modulated layered structure with modulation. For the first time, the atomic positions of the Ca and Co atoms in the Ca(2)CoO(3) block were identified, corresponding to three rows of dark spots in the [110] direction. The observed HRTEM images for Ca(2)CoO(3) agreed well with the calculated images based on the structural model obtained by the Rietveld refinement method.

Calcium↗

PubMed2003

Testosterone causes simultaneous decrease of [Ca2+]I and tension in rabbit coronary arteries: by opening voltage dependent potassium channels.

The relationship between the level of testosterone and the incidence of coronary heart disease is still controversial in the view of the results of clinical and epidemiologic studies. This uncertainty might be partly due to relatively small number of experimental studies undertaken to investigate the cellular mechanism underlying the vascular responses to testosterone. To further investigate the cellular mechanisms of testosterone with respect to vascular response, we investigated the effect of testosterone on contractility and intracellular Ca2+ regulation in a rabbit coronary artery and evaluated the underlying mechanism of testosterone-induced changes of coronary vascular tone by using various pharmacological blockers. Testosterone was found to relax rabbit coronary arteries in a dose-dependent manner, and no significant difference was found in the relaxation response to testosterone with or without endothelium. Similar results were obtained in male and non-pregnant female rabbit coronary arteries. The relaxation response of rabbit coronary arteries to testosterone was greater for PGF2alpha-contracted rings than for KCl contracted rings, which suggest the involvement of K+ channels. Furthermore, the relaxation response to testosterone was significantly reduced by 4-aminopyridine, a sensitive blocker of voltage dependent K+ channels, but not by low doses of tetraethylammonium or iberiotoxin, a Ca2+ activated K+ channel blocker. Testosterone simultaneously reduced the intracellular Ca2+ concentration ([Ca2+]i) and tension, and 4-AP effectively antagonized the testosterone-induced change of [Ca2+]i and tension. Therefore, it may be concluded that the stimulation of voltage dependent K channels is responsible, at least in part, for the testosterone-induced relaxation of rabbit coronary arteries.

Androgens↗