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Biomedical subjects

J H Yoon

Publications and source records attributed to J H Yoon.

At least 19 recordsLinked to original sources
PubMed1996

Occlusion of large atrial septal defects with a centering buttoned device: early clinical experience.

A feasibility clinical study was conducted for the transcatheter occlusion of large ostium secundum atrial septal defects with the centering buttoned device. The centering buttoned device is a modification of the regular buttoned device in which a centering counter-occluder is sutured at the central 40% portion of the occluder. During centering it is stretched, forming a parachute-shaped structure and pulling the occluder over the center of the defect. During buttoning, the counter-occluder forms a double figure eight, opposing the right atrial side of the atrial septum. Occlusion was performed in 12 patients aged 6 to 56 years. All had been rejected for transcatheter occlusion by the regular buttoned device, because of either their defect size or the lack of adequate septal rim. The defect size varied between 23 and 31 mm, and the device size varied between 45 and 60 mm. Nine had immediate effective occlusions of their defects and three residual shunts. One patient with unbuttoning had hemolysis at 2 weeks and underwent surgery. Early results of the transcatheter occlusion of large atrial septal defects are promising, and larger clinical trials are justified.

Adolescent↗
PubMed1995

The Aspergillus uvsH gene encodes a product homologous to yeast RAD18 and Neurospora UVS-2.

The uvsH DNA repair gene of Aspergillus nidulans has been cloned by complementation of the uvsH77 mutation with a cosmid library containing genomic DNA inserts from a wild-type strain. Methylmethane sulfonate (MMS)-resistant transformants were obtained on medium containing 0.01% MMS, to which uvsH mutants exhibit high sensitivity. Retransformation of uvsH77 mutants with the rescued cosmids from the MMS-resistant transformants resulted in restoration of both UV and MMS resistance to wild-type levels. Nucleotide sequence analysis of the genomic DNA and cDNA of the uvsH gene shows that it has an open reading frame (ORF) of 1329 bp, interrupted by two introns of 51 and 61 bp. A 2.4 kb transcript of the uvsH gene was detected by Northern blot analysis. Primer extension analysis revealed that transcription starts at 31 bp upstream from the translation initiation codon. This gene encodes a predicted polypeptide of 443 amino acids, which has two unique zinc finger motifs. The proposed polypeptide displays 39% identity to the Neurospora crassa UVS-2 protein and 24% identity to the Saccharomyces cerevisiae RAD18 protein. The sequence similarity is particularly high in three domains. One zinc finger (RING finger) motif is located in the first domain close to the N-terminus. The other zinc finger motif is in the second domain. In the third domain, the mutation sites in both the uvsH77 and uvsH304 alleles were identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1995

Isolation and characterization of the promoter region of the rat DNA topoisomerase II alpha gene.

A genomic DNA clone containing the 5'-end of the rat topo II alpha gene was isolated and the intron/exon structure of a 4.0 kb region encompassing the translation initiation site was determined. Multiple transcription initiation sites were found at positions -128, -110, and -100 bp upstream of the ATG codon. A minimal promoter region extending from -192 to the translation initiation codon was identified on transient expression analysis. This region lacks a TATA motif, is moderately GC-rich and contains a high number of CpG dinucleotides, which is characteristic of a housekeeping gene promoter. The fragment extending to position -242 exhibited maximal promoter activity. Putative regulatory elements were delineated within and immediately upstream of the minimal promoter region. On gel retardation and DNase I footprint analyses, two regions, between positions -195 to -159 which interact with protein factor(s) were identified. The minimal promoter region of the rat topo II alpha gene showed high sequence homology with that of human topo II alpha. In a 250 bp region upstream of the translation initiation site, the sequence identity was about 70%. The basic structure of the regulatory region of the rat topo II alpha gene was found to be similar to that of the human counterpart.

Animals↗
PubMed1995

A phylogenetic analysis of the genus Saccharomonospora conducted with 16S rRNA gene sequences.

Nearly complete sequences of 16S rRNA genes of representative strains of the genus Saccharomonospora were determined following the isolation and cloning of the amplified genes. The sequences were aligned with those of representatives of the family Pseudonocardiaceae, and a phylogenetic tree was inferred by the neighbor-joining method. The genus Saccharomonospora formed a distinct clade within the evolutionary radiation encompassed by the family Pseudonocardiaceae. The average nucleotide similarity value found between the type strains of the four validly described Saccharomonospora species was 97.5% +/- 1.0%. The most distant relationship was found between Saccharomonospora azurea and Saccharomonospora viridis K73 (96.3% similarity). In contrast, Saccharomonospora azurea K161 and "Saccharomonospora caesia" K163 had identical 16S rRNA gene sequences. The nucleotide sequence data suggest that the genus Saccharomonospora contains several new centers of variation.

Actinomycetales↗
PubMed1995

A 33 kDa Pit-1-like protein binds to the distal region of the human thyrotrophin alpha-subunit gene.

Our previous studies demonstrated that at least two DNA regions with upstream limits between positions -223 to -190 and positions -151 to -135 of the human TSH gene are important for transcriptional regulation by TRH in GH3 rat pituitary cells. The proximal region (-151 to -135 bp) including the cAMP-responsive element (CRE) was required for the induction of the TSH gene by TRH, while the distal region (-223 to -190 bp) containing an element similar to the binding site for the pituitary-specific transcription factor, Pit-1, was necessary to amplify the effects of TRH. To determine whether a pituitary-specific nuclear protein, in addition to the CRE-binding protein, is involved in the molecular mechanism of TRH regulation, a gel retardation assay and Southwestern blot analysis were performed on the distal region with GH3 cell nuclear extracts. GH3 extracts generated a distinct DNA-protein complex that was effectively eliminated in the presence of excess unlabelled DNA fragment, and TRH treatment increased the affinity of protein binding remarkably. Excess Pit-1 DNA-binding sequence from the rat prolactin gene inhibited formation of the complex, but mutation of the Pit-1 consensus sequence in the distal region did not eliminate the complex. In addition, Southwestern experiments showed that a 33 kDa nuclear protein present in GH3 cells bound to this region and its binding affinity was increased slightly 2 h after TRH treatment, with the maximal increase (fivefold) at 3 h, which was similar to the results when using gel retardation. Phosphatase treatment of nuclear protein also resulted in a loss of binding affinity. Taken together, these data indicate that the interaction of a pituitary-specific nuclear protein, identical or closely related to Pit-1, with the distal region may be involved in the TRH stimulation of human TSH gene expression.

Animals↗
PubMed1995

Frequent reactivations of anti-HBe-positive chronic hepatitis B in patients with no demonstrable HBV DNA in serum by polymerase chain reaction.

OBJECTIVES: The present study was conducted to evaluate the prognostic significance of the absence of serum HBV DNA by polymerase chain reaction (PCR) after spontaneous HBeAg/anti-HBe seroconversion and concurrent or subsequent biochemical remission. METHODS: We prospectively investigated the reactivation rates in 28 chronic hepatitis B patients according to the positive or negative serum HBV DNA test by PCR. The sera drawn at a mean period of 4.4 months after normalization of alanine aminotransferase (ALT) were analyzed by PCR-Southern blot hybridization to detect HBV DNA, and then the patients were divided into two groups according to the presence (n = 14) or absence (n = 14) of HBV DNA in the sera. RESULTS: The cumulative reactivation rates in patients with HBV DNA in sera were 43%, 57%, 57%, 57% and 57% at the end of 1st, 2nd, 3rd, 4th and 5th year after normalization of ALT, respectively, and those in patients without demonstrable HBV DNA were 50%, 66%, 74%, 74% and 83%, respectively; thus, the difference in the cumulative reactivation rates between patients with and without serum HBV DNA was not statistically significant (p = 0.79), and irrespective of the status of HBV DNA in sera by PCR, reactivations occurred very rarely after 2 years of a sustained remission. CONCLUSIONS: We conclude that the seroconversion to anti-HBe accompanied by disappearance of serum HBV DNA even by PCR does not necessarily suggest a sustained remission of chronic hepatitis B.

Adult↗
PubMed1994

Involvement of a cAMP-responsive DNA element in mediating TRH responsiveness of the human thyrotropin alpha-subunit gene.

TRH is known to stimulate the transcription of the TSH gene in pituitary cells. To examine TRH-responsive elements of the human TSH alpha-subunit gene, we have used transient transfection of GH3 rat pituitary tumor cells. Using this system, TRH treatment stimulated expression of a reporter gene containing 846 base pairs from the 5'-flanking region of the human glycoprotein hormone alpha-subunit gene linked to luciferase. Analysis of 5'-deletions of the alpha-subunit sequence revealed that at least two DNA regions with upstream limits between positions -223 to -190 and positions -151 to -135 are important for regulation by TRH. The more proximal region includes a previously defined cAMP-response element (CRE) while the more upstream region contains an element with sequence similarity to the binding site for the pituitary transcription factor, Pit-1. The TRH responsiveness of each individual region was tested by inserting fragments upstream of a thymidine kinase-luciferase reporter gene. The -151 to -100 region had basal enhancer activity and permitted a 3.4-fold response to TRH. The -223 to -168 region did not permit a TRH response, but possessed basal enhancer activity. The combination of both regions resulted in a 5-fold stimulation by TRH. To assess the contributions of different signal transduction pathways, various combinations of treatments were examined. Combined treatment with TRH and forskolin led to an additive activity. Treatment with TRH plus phorbol 12-myristate-13-acetate resulted in the same level of reporter gene activity as with either agent alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Mechanism of decrease in heart rate by peripheral dopaminergic D2-receptors.

We performed this study in order to verify the heart rate decrease caused by the D2-receptor on cardiac sympathetic nerve endings and its relation to the concentration of norepinephrine in synaptic clefts. Sprague-Dawley rats were pithed and the heart rate was increased either by electrical stimulation of the cardiac accelerator nerve or by intravenous infusion of norepinephrine, tyramine, or isoproterenol. Increased heart rate by electrical stimulation of cardiac accelerator nerve was dose-dependently lowered by lisuride and its effect was blocked by pretreatment with sulpiride but not with yohimbine and SCH 23390. Also, the heart rate was decreased in a dose-dependent manner by clonidine and this effect was blocked by pretreatment with yohimbine, but not with sulpiride. For increased heart rate by infusion of norepinephrine, tyramine, or isoproterenol, the heart rate lowering effect of lisuride was more marked in the norepinephrine-and tyramine-infusion groups, in which the intrasynaptic concentration of norepinephrine was elevated, compared to the isoproterenol-infusion group, in which intrasynaptic concentration of norepinephrine was not elevated. In conclusion, there is a D2-receptor on the cardiac sympathetic nerve endings which decreases the heart rate and is different from the presynaptic alpha 2-receptor. Also, the heart rate lowering effect via stimulation of the D2-receptor by lisuride was more marked with increased concentration of norepinephrine in the synaptic cleft.

Animals↗
PubMed1993

Nucleotide sequence analysis of the CDNA for rat DNA topoisomerase II.

CDNA clones encoding the rat DNA topoisomerase II were isolated from rat testis CDNA library using a DNA probe synthesized by two sequential nested PCRs. The nucleotide sequence of the entire coding region and its deduced 1526 amino acid sequence showed that 80% nucleotides and 89% amino acids were identical with human HeLa DNA topoisomerase II gene (hTOP2). Approximately 1100 amino acids at the N-terminus shows 96.5% sequence identity, but C-terminus has only 65% homology. Rat DNA topoisomerase II gene (rTOP2) contains three functional domains responsible for ATPase activity, break-reunion activity, and complex stability and DNA binding activity like other eukaryotic TOP2. It also contains two putative nuclear targeting sequences and a leucine zipper motif and has highly charged species specific sequences at the C-terminus.

Amino Acid Sequence↗
PubMed1993

Transient spontaneous remission in acute promyelocytic leukemia--two case reports.

Two cases of spontaneous remission in acute promyelocytic leukemia are reported. They had precedent febrile episodes and subsequent resolution of all clinical and hematological abnormalities occurred after supportive care including administration of various antibiotics. Their remissions lasted for 12 and five months respectively, when they relapsed.

Adult↗
PubMed1993

Percutaneous mitral balloon valvuloplasty in patients with restenosis after surgical commissurotomy: a comparative study.

We performed percutaneous mitral balloon valvuloplasty (PMV) in 367 patients to compare the effectiveness of PMV between patients with mitral restenosis after surgical commissurotomy (group 1) and patients with unoperated mitral stenosis (group 2). Twenty-two had undergone closed or open mitral commissurotomy 11.2 years before. There were no significant differences in clinical profiles between the two groups. The mitral valve area was increased from 1.0 +/- 0.8 to 1.8 +/- 0.6 cm2 in group 1 and 0.9 +/- 0.3 to 2.0 +/- 0.7 cm2 in group 2 (p > 0.05). The mitral gradient was decreased from 14 +/- 5.9 to 6 +/- 2.6 mmHg in group 1 and 18 +/- 7.0 to 7 +/- 5.3 mmHg in group 2 (p > 0.05). The increment of mitral regurgitation and significant left to right shunt after PMV were not significantly different (10% versus 14.7%, 5% versus 10.4% respectively). Optimal results were attained in 75% of the patients in group 1 and in 84.3% of the patients in group 2 (p > 0.05). These results suggest PMV in mitral restenosis after surgical commissurotomy may be safe in selected patients and may be equally effective as in unoperated mitral stenosis.

Adult↗
PubMed1993

Antral Helicobacter pylori infection, hypergastrinemia and peptic ulcers: effect of eradicating the organism.

BACKGROUND: A randomized prospective study on the response of fasting serum gastrin concentrations in peptic ulcer patients was performed in order to test the hypothesis that H. pylori infection in the gastric antrum increases gastrin release, and to examine whether the high fasting serum gastrin concentrations respond to treatment that eradicates H. pylori. METHODS: One hundred and twenty-seven patients with gastric or duodenal ulcer were included in this study. Patients were divided into three groups on the basis of antral H. pylori status and therapeutic modalities. The first group, 58 patients infected by H. pylori, was treated with metronidazole and tripotassium dicitrato bismuthate combined with ranitidine and mylanta. The second group, 40 patients also infected by H. Pylori, was treated with ranitidine and mylanta. The third group, 29 patients, free of H. pylori infection, was designed to evaluate the influence of H2-receptor antagonist on the change of gastrin. When ulcers were completely healed, changes of gastrin concentrations and H. pylori status were re-examined. RESULTS: H. pylori was eradicated in all patients who have received antibacterial therapy in 4 weeks, and serum gastrin concentrations were significantly decreased after eradication of the organism both in gastric and in duodenal ulcer diseases. (Gastric ulcer: 129.3 +/- 47.0 pg/ml before and 63.7 +/- 21.6 pg/ml after treatment. Duodenal ulcer: 108.3 +/- 35.0 pg/ml and 66.5 +/- 21.9 pg/ml, respectively. Total: 112.7 +/- 38.2 pg/ml vs 66.0 +/- 21.6 pg/ml) (p < 0.01). In contrast, H. pylori-positive patients who have not received antibacterial therapy were still infected at the completion of the study, and serum gastrin concentrations increased even though the difference was not significant. (Gastric ulcer: 118.4 +/- 51.2 pg/ml vs 124.0 +/- 56.5 pg/ml. Duodenal ulcer: 85.4 +/- 35.1 pg/ml vs 104.6 +/- 43.5. Total: 99.5 +/- 45.3 vs 112.9 +/- 48.7 pg/ml.) (p > 0.05). None of the patients who were initially H. pylori-negative has been reinfected during the period of the study, and their serum gastrin concentrations were not changed. (Gastric ulcer: 69.8 +/- 38.0 pg/ml. Total: 63.2 +/- 31.1 pg/ml. Duodenal ulcer: 55.1 +/- 17.6 pg/ml vs 55.8 +/- 13.8 pg/ml. Total: 63.2 +/- 31.1 pg/ml vs 63.4 +/- 30.0 pg/ml). Four- to six-week therapy of H2-receptor antagonist and antacid had no influence on serum gastrin concentrations. CONCLUSIONS: On the basis of the above results, we confirmed that the chronic infection of H. pylori of gastric antrum in peptic ulcer patients causes increased release of serum gastrin, and eradication of the organism results in a significant fall in serum gastrin concentrations.

Adolescent↗
PubMed1992

Temporalis muscle as a disc replacement in the temporomandibular joint of sheep.

Temporalis muscle flaps were evaluated in sheep. Flaps placed following discectomy were examined at 2, 4, 12, and 24 weeks. Histologic evaluation showed avascular necrosis and subsequent displacement and loss of tissue from the joint resulting in close contact between the condyle and fossa. Muscle flaps placed lateral to the joint in operative controls were examined at 4, 12, and 24 weeks. This muscle remained viable while undergoing fibrous replacement. Although the surface layers of the condyle and fossa were initially lost, the tissues were reformed with time. This experiment showed that in the sheep, temporalis muscle does not withstand functional loading within the joint. However, despite the lack of interpositional material, the condyle and fossa can remodel.

Animals↗
PubMed1992

Comparison of outcome among double, bifoil and Inoue balloon techniques for percutaneous mitral valvuloplasty in mitral stenosis.

The efficacy and complications of three different methods of percutaneous mitral valvuloplasty (PMV) were evaluated in 245 patients with mitral stenosis (MS). Eight six patients (35%) had severe MS defined in the mitral valve area (MVA) less than 1.0 cm2 (0.8 +/- 0.2) and Echoscore greater than or equal to 8(8.9 +/- 1.1). The results including post MCA greater than or equal to 1.5cm2 and complications, i.e, increment of mitral regurgitation (MR) greater than or equal to +1 and atrial septal defect (ASD) with Qp/Qs greater than or equal to 1.5 were compared in overall and in severe MS groups. There was no statistically significant difference in size of MVA before and after PMV between overall patients group and severe mitral stenosis group (0.8 +/- 0.1 vs 1.7 +/- 0.4cm2 in the double technique, 0.8 +/- 0.2 vs 1.5 +/- 0.3cm2 in the Bifoil technique and 0.7 +/- 0.2 vs 1.8 +/- 0.3cm2 in the Inoue technique. p: NS). However, a significantly larger number of patients in the severe MS group had better MVA with the double than the Bifoil technique [MVA greater than or equal to 1.5cm2; 42 (72%) vs 6 (46%), p less than 0.005] whereas higher complications were observed with the Bifoil than the Inoue technique (MR greater than or equal to +1; 9 (69%) vs 4 (27%), ASD (Qp/Qs greater than or equal to 1.5' 6 (46%) vs 2 (13%) p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Atypical clinical manifestations of amebic colitis.

Amebic colitis is a disease revealing diverse clinical manifestations and endoscopic gross features and often confused with other types of colitis. In case of misdiagnosis as an idiopathic inflammatory bowel disease or delayed recognition of intestinal amebiasis, an undesirable outcome may occur resulting from erroneous administration of steroids or delayed antiamebic treatment. To demonstrate the pitfalls in the diagnosis and treatment of intestinal amebiasis, 3 cases of amebic colitis with atypical clinical manifestations are presented in this paper. In conclusion, despite the low sensitivities of routine stool examination for parasite and histopathologic confirmation in biopsy specimen, every effort must be made to find amebic trophozoites either in fresh stool or biopsy specimens for prompt and correct diagnosis of amebic colitis when we manage patients with chronic intestinal ulcerations, even though their clinical course and endoscopic findings are not typical of amebiasis. Moreover, following initial successful anti-amebic therapy, more careful clinical, endoscopical, and parasitological follow-up should be done for the early detection of recurrence.

Adult↗
PubMed1989

A case of recurrent infantile polycystic kidney associated with hydrops fetalis.

Nonimmune hydrops fetalis is becoming a predominant form of fetal hydrops due to the declining incidence of immune hydrops fetalis triggered by Rh isoimmunization. Infantile polycystic kidney appeared to be related to hydrops fetalis whether it is causal or merely coincidental and may represent another entry to differential diagnoses. Infantile polycystic kidney was diagnosed by an elevated maternal serum alpha-fetoprotein (AFP) value coupled with an ultrasonographic abnormality scanned as a multicystic mass with ascites in the fetal abdomen antenatally. This study presents a case of infantile polycystic kidney that resulted in a stillborn baby with hydrops fetalis and extensive placental calcification; it was the first case in Korea in which nonimmune hydrops fetalis was associated with infantile polycystic kidney in consecutive siblings by autosomal recessive inheritance in one family. In addition, this paper comprehensively reviews the incidence, etiology, prenatal diagnosis and proper management of nonimmune hydrops fetalis.

Adult↗
PubMed1989

Clinical and histopathological study of fibro-osseous lesions of the jaws.

Seventy-two cases of benign fibro-osseous lesions of the jaws were reassessed, and a modified classification is proposed that may be helpful in their understanding and management. The anatomical distribution of these cases is described and compared to previously reported cases. The histogenesis of each particular lesion is also discussed. Correlative analysis of histopathologic and oral radiographic features is essential for definitive diagnosis.

Adolescent↗